/src/postgres/src/backend/commands/trigger.c

Source
/*-------------------------------------------------------------------------
 *
 * trigger.c
 *    PostgreSQL TRIGGERs support code.
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/backend/commands/trigger.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/htup_details.h"
#include "access/relation.h"
#include "access/sysattr.h"
#include "access/table.h"
#include "access/tableam.h"
#include "access/tupconvert.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/objectaccess.h"
#include "catalog/partition.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_trigger.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "executor/executor.h"
#include "executor/instrument.h"
#include "miscadmin.h"
#include "nodes/bitmapset.h"
#include "nodes/makefuncs.h"
#include "optimizer/optimizer.h"
#include "parser/parse_clause.h"
#include "parser/parse_collate.h"
#include "parser/parse_func.h"
#include "parser/parse_relation.h"
#include "partitioning/partdesc.h"
#include "pgstat.h"
#include "rewrite/rewriteHandler.h"
#include "rewrite/rewriteManip.h"
#include "storage/lmgr.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/guc_hooks.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/plancache.h"
#include "utils/rel.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
#include "utils/tuplestore.h"


/* GUC variables */
int     SessionReplicationRole = SESSION_REPLICATION_ROLE_ORIGIN;

/* How many levels deep into trigger execution are we? */
static int  MyTriggerDepth = 0;

/* Local function prototypes */
static void renametrig_internal(Relation tgrel, Relation targetrel,
                HeapTuple trigtup, const char *newname,
                const char *expected_name);
static void renametrig_partition(Relation tgrel, Oid partitionId,
                 Oid parentTriggerOid, const char *newname,
                 const char *expected_name);
static void SetTriggerFlags(TriggerDesc *trigdesc, Trigger *trigger);
static bool GetTupleForTrigger(EState *estate,
                 EPQState *epqstate,
                 ResultRelInfo *relinfo,
                 ItemPointer tid,
                 LockTupleMode lockmode,
                 TupleTableSlot *oldslot,
                 bool do_epq_recheck,
                 TupleTableSlot **epqslot,
                 TM_Result *tmresultp,
                 TM_FailureData *tmfdp);
static bool TriggerEnabled(EState *estate, ResultRelInfo *relinfo,
               Trigger *trigger, TriggerEvent event,
               Bitmapset *modifiedCols,
               TupleTableSlot *oldslot, TupleTableSlot *newslot);
static HeapTuple ExecCallTriggerFunc(TriggerData *trigdata,
                   int tgindx,
                   FmgrInfo *finfo,
                   TriggerInstrumentation *instr,
                   MemoryContext per_tuple_context);
static void AfterTriggerSaveEvent(EState *estate, ResultRelInfo *relinfo,
                  ResultRelInfo *src_partinfo,
                  ResultRelInfo *dst_partinfo,
                  int event, bool row_trigger,
                  TupleTableSlot *oldslot, TupleTableSlot *newslot,
                  List *recheckIndexes, Bitmapset *modifiedCols,
                  TransitionCaptureState *transition_capture,
                  bool is_crosspart_update);
static void AfterTriggerEnlargeQueryState(void);
static bool before_stmt_triggers_fired(Oid relid, CmdType cmdType);
static HeapTuple check_modified_virtual_generated(TupleDesc tupdesc, HeapTuple tuple);


/*
 * Create a trigger.  Returns the address of the created trigger.
 *
 * queryString is the source text of the CREATE TRIGGER command.
 * This must be supplied if a whenClause is specified, else it can be NULL.
 *
 * relOid, if nonzero, is the relation on which the trigger should be
 * created.  If zero, the name provided in the statement will be looked up.
 *
 * refRelOid, if nonzero, is the relation to which the constraint trigger
 * refers.  If zero, the constraint relation name provided in the statement
 * will be looked up as needed.
 *
 * constraintOid, if nonzero, says that this trigger is being created
 * internally to implement that constraint.  A suitable pg_depend entry will
 * be made to link the trigger to that constraint.  constraintOid is zero when
 * executing a user-entered CREATE TRIGGER command.  (For CREATE CONSTRAINT
 * TRIGGER, we build a pg_constraint entry internally.)
 *
 * indexOid, if nonzero, is the OID of an index associated with the constraint.
 * We do nothing with this except store it into pg_trigger.tgconstrindid;
 * but when creating a trigger for a deferrable unique constraint on a
 * partitioned table, its children are looked up.  Note we don't cope with
 * invalid indexes in that case.
 *
 * funcoid, if nonzero, is the OID of the function to invoke.  When this is
 * given, stmt->funcname is ignored.
 *
 * parentTriggerOid, if nonzero, is a trigger that begets this one; so that
 * if that trigger is dropped, this one should be too.  There are two cases
 * when a nonzero value is passed for this: 1) when this function recurses to
 * create the trigger on partitions, 2) when creating child foreign key
 * triggers; see CreateFKCheckTrigger() and createForeignKeyActionTriggers().
 *
 * If whenClause is passed, it is an already-transformed expression for
 * WHEN.  In this case, we ignore any that may come in stmt->whenClause.
 *
 * If isInternal is true then this is an internally-generated trigger.
 * This argument sets the tgisinternal field of the pg_trigger entry, and
 * if true causes us to modify the given trigger name to ensure uniqueness.
 *
 * When isInternal is not true we require ACL_TRIGGER permissions on the
 * relation, as well as ACL_EXECUTE on the trigger function.  For internal
 * triggers the caller must apply any required permission checks.
 *
 * When called on partitioned tables, this function recurses to create the
 * trigger on all the partitions, except if isInternal is true, in which
 * case caller is expected to execute recursion on its own.  in_partition
 * indicates such a recursive call; outside callers should pass "false"
 * (but see CloneRowTriggersToPartition).
 */
ObjectAddress
CreateTrigger(const CreateTrigStmt *stmt, const char *queryString,
        Oid relOid, Oid refRelOid, Oid constraintOid, Oid indexOid,
        Oid funcoid, Oid parentTriggerOid, Node *whenClause,
        bool isInternal, bool in_partition)
{
  return
    CreateTriggerFiringOn(stmt, queryString, relOid, refRelOid,
                constraintOid, indexOid, funcoid,
                parentTriggerOid, whenClause, isInternal,
                in_partition, TRIGGER_FIRES_ON_ORIGIN);
}

/*
 * Like the above; additionally the firing condition
 * (always/origin/replica/disabled) can be specified.
 */
ObjectAddress
CreateTriggerFiringOn(const CreateTrigStmt *stmt, const char *queryString,
            Oid relOid, Oid refRelOid, Oid constraintOid,
            Oid indexOid, Oid funcoid, Oid parentTriggerOid,
            Node *whenClause, bool isInternal, bool in_partition,
            char trigger_fires_when)
{
  int16   tgtype;
  int     ncolumns;
  int16    *columns;
  int2vector *tgattr;
  List     *whenRtable;
  char     *qual;
  Datum   values[Natts_pg_trigger];
  bool    nulls[Natts_pg_trigger];
  Relation  rel;
  AclResult aclresult;
  Relation  tgrel;
  Relation  pgrel;
  HeapTuple tuple = NULL;
  Oid     funcrettype;
  Oid     trigoid = InvalidOid;
  char    internaltrigname[NAMEDATALEN];
  char     *trigname;
  Oid     constrrelid = InvalidOid;
  ObjectAddress myself,
        referenced;
  char     *oldtablename = NULL;
  char     *newtablename = NULL;
  bool    partition_recurse;
  bool    trigger_exists = false;
  Oid     existing_constraint_oid = InvalidOid;
  bool    existing_isInternal = false;
  bool    existing_isClone = false;

  if (OidIsValid(relOid))
    rel = table_open(relOid, ShareRowExclusiveLock);
  else
    rel = table_openrv(stmt->relation, ShareRowExclusiveLock);

  /*
   * Triggers must be on tables or views, and there are additional
   * relation-type-specific restrictions.
   */
  if (rel->rd_rel->relkind == RELKIND_RELATION)
  {
    /* Tables can't have INSTEAD OF triggers */
    if (stmt->timing != TRIGGER_TYPE_BEFORE &&
      stmt->timing != TRIGGER_TYPE_AFTER)
      ereport(ERROR,
          (errcode(ERRCODE_WRONG_OBJECT_TYPE),
           errmsg("\"%s\" is a table",
              RelationGetRelationName(rel)),
           errdetail("Tables cannot have INSTEAD OF triggers.")));
  }
  else if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
  {
    /* Partitioned tables can't have INSTEAD OF triggers */
    if (stmt->timing != TRIGGER_TYPE_BEFORE &&
      stmt->timing != TRIGGER_TYPE_AFTER)
      ereport(ERROR,
          (errcode(ERRCODE_WRONG_OBJECT_TYPE),
           errmsg("\"%s\" is a table",
              RelationGetRelationName(rel)),
           errdetail("Tables cannot have INSTEAD OF triggers.")));

    /*
     * FOR EACH ROW triggers have further restrictions
     */
    if (stmt->row)
    {
      /*
       * Disallow use of transition tables.
       *
       * Note that we have another restriction about transition tables
       * in partitions; search for 'has_superclass' below for an
       * explanation.  The check here is just to protect from the fact
       * that if we allowed it here, the creation would succeed for a
       * partitioned table with no partitions, but would be blocked by
       * the other restriction when the first partition was created,
       * which is very unfriendly behavior.
       */
      if (stmt->transitionRels != NIL)
        ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("\"%s\" is a partitioned table",
                RelationGetRelationName(rel)),
             errdetail("ROW triggers with transition tables are not supported on partitioned tables.")));
    }
  }
  else if (rel->rd_rel->relkind == RELKIND_VIEW)
  {
    /*
     * Views can have INSTEAD OF triggers (which we check below are
     * row-level), or statement-level BEFORE/AFTER triggers.
     */
    if (stmt->timing != TRIGGER_TYPE_INSTEAD && stmt->row)
      ereport(ERROR,
          (errcode(ERRCODE_WRONG_OBJECT_TYPE),
           errmsg("\"%s\" is a view",
              RelationGetRelationName(rel)),
           errdetail("Views cannot have row-level BEFORE or AFTER triggers.")));
    /* Disallow TRUNCATE triggers on VIEWs */
    if (TRIGGER_FOR_TRUNCATE(stmt->events))
      ereport(ERROR,
          (errcode(ERRCODE_WRONG_OBJECT_TYPE),
           errmsg("\"%s\" is a view",
              RelationGetRelationName(rel)),
           errdetail("Views cannot have TRUNCATE triggers.")));
  }
  else if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
  {
    if (stmt->timing != TRIGGER_TYPE_BEFORE &&
      stmt->timing != TRIGGER_TYPE_AFTER)
      ereport(ERROR,
          (errcode(ERRCODE_WRONG_OBJECT_TYPE),
           errmsg("\"%s\" is a foreign table",
              RelationGetRelationName(rel)),
           errdetail("Foreign tables cannot have INSTEAD OF triggers.")));

    /*
     * We disallow constraint triggers to protect the assumption that
     * triggers on FKs can't be deferred.  See notes with AfterTriggers
     * data structures, below.
     */
    if (stmt->isconstraint)
      ereport(ERROR,
          (errcode(ERRCODE_WRONG_OBJECT_TYPE),
           errmsg("\"%s\" is a foreign table",
              RelationGetRelationName(rel)),
           errdetail("Foreign tables cannot have constraint triggers.")));
  }
  else
    ereport(ERROR,
        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
         errmsg("relation \"%s\" cannot have triggers",
            RelationGetRelationName(rel)),
         errdetail_relkind_not_supported(rel->rd_rel->relkind)));

  /*
   * Conflict log tables are used internally for logical replication
   * conflict logging and should not have triggers, as it could disrupt
   * conflict logging.
   */
  if (IsConflictLogTableClass(rel->rd_rel))
    ereport(ERROR,
        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
         errmsg("cannot create trigger on conflict log table \"%s\"",
            RelationGetRelationName(rel)),
         errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));

  if (!allowSystemTableMods && IsSystemRelation(rel))
    ereport(ERROR,
        (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
         errmsg("permission denied: \"%s\" is a system catalog",
            RelationGetRelationName(rel))));

  if (stmt->isconstraint)
  {
    /*
     * We must take a lock on the target relation to protect against
     * concurrent drop.  It's not clear that AccessShareLock is strong
     * enough, but we certainly need at least that much... otherwise, we
     * might end up creating a pg_constraint entry referencing a
     * nonexistent table.
     */
    if (OidIsValid(refRelOid))
    {
      LockRelationOid(refRelOid, AccessShareLock);
      constrrelid = refRelOid;
    }
    else if (stmt->constrrel != NULL)
      constrrelid = RangeVarGetRelid(stmt->constrrel, AccessShareLock,
                       false);
  }

  /* permission checks */
  if (!isInternal)
  {
    aclresult = pg_class_aclcheck(RelationGetRelid(rel), GetUserId(),
                    ACL_TRIGGER);
    if (aclresult != ACLCHECK_OK)
      aclcheck_error(aclresult, get_relkind_objtype(rel->rd_rel->relkind),
               RelationGetRelationName(rel));

    if (OidIsValid(constrrelid))
    {
      aclresult = pg_class_aclcheck(constrrelid, GetUserId(),
                      ACL_TRIGGER);
      if (aclresult != ACLCHECK_OK)
        aclcheck_error(aclresult, get_relkind_objtype(get_rel_relkind(constrrelid)),
                 get_rel_name(constrrelid));
    }
  }

  /*
   * When called on a partitioned table to create a FOR EACH ROW trigger
   * that's not internal, we create one trigger for each partition, too.
   *
   * For that, we'd better hold lock on all of them ahead of time.
   */
  partition_recurse = !isInternal && stmt->row &&
    rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE;
  if (partition_recurse)
    list_free(find_all_inheritors(RelationGetRelid(rel),
                    ShareRowExclusiveLock, NULL));

  /* Compute tgtype */
  TRIGGER_CLEAR_TYPE(tgtype);
  if (stmt->row)
    TRIGGER_SETT_ROW(tgtype);
  tgtype |= stmt->timing;
  tgtype |= stmt->events;

  /* Disallow ROW-level TRUNCATE triggers */
  if (TRIGGER_FOR_ROW(tgtype) && TRIGGER_FOR_TRUNCATE(tgtype))
    ereport(ERROR,
        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
         errmsg("TRUNCATE FOR EACH ROW triggers are not supported")));

  /* INSTEAD triggers must be row-level, and can't have WHEN or columns */
  if (TRIGGER_FOR_INSTEAD(tgtype))
  {
    if (!TRIGGER_FOR_ROW(tgtype))
      ereport(ERROR,
          (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
           errmsg("INSTEAD OF triggers must be FOR EACH ROW")));
    if (stmt->whenClause)
      ereport(ERROR,
          (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
           errmsg("INSTEAD OF triggers cannot have WHEN conditions")));
    if (stmt->columns != NIL)
      ereport(ERROR,
          (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
           errmsg("INSTEAD OF triggers cannot have column lists")));
  }

  /*
   * We don't yet support naming ROW transition variables, but the parser
   * recognizes the syntax so we can give a nicer message here.
   *
   * Per standard, REFERENCING TABLE names are only allowed on AFTER
   * triggers.  Per standard, REFERENCING ROW names are not allowed with FOR
   * EACH STATEMENT.  Per standard, each OLD/NEW, ROW/TABLE permutation is
   * only allowed once.  Per standard, OLD may not be specified when
   * creating a trigger only for INSERT, and NEW may not be specified when
   * creating a trigger only for DELETE.
   *
   * Notice that the standard allows an AFTER ... FOR EACH ROW trigger to
   * reference both ROW and TABLE transition data.
   */
  if (stmt->transitionRels != NIL)
  {
    List     *varList = stmt->transitionRels;
    ListCell   *lc;

    foreach(lc, varList)
    {
      TriggerTransition *tt = lfirst_node(TriggerTransition, lc);

      if (!(tt->isTable))
        ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("ROW variable naming in the REFERENCING clause is not supported"),
             errhint("Use OLD TABLE or NEW TABLE for naming transition tables.")));

      /*
       * Because of the above test, we omit further ROW-related testing
       * below.  If we later allow naming OLD and NEW ROW variables,
       * adjustments will be needed below.
       */

      if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
        ereport(ERROR,
            (errcode(ERRCODE_WRONG_OBJECT_TYPE),
             errmsg("\"%s\" is a foreign table",
                RelationGetRelationName(rel)),
             errdetail("Triggers on foreign tables cannot have transition tables.")));

      if (rel->rd_rel->relkind == RELKIND_VIEW)
        ereport(ERROR,
            (errcode(ERRCODE_WRONG_OBJECT_TYPE),
             errmsg("\"%s\" is a view",
                RelationGetRelationName(rel)),
             errdetail("Triggers on views cannot have transition tables.")));

      /*
       * We currently don't allow row-level triggers with transition
       * tables on partition or inheritance children.  Such triggers
       * would somehow need to see tuples converted to the format of the
       * table they're attached to, and it's not clear which subset of
       * tuples each child should see.  See also the prohibitions in
       * ATExecAttachPartition() and ATExecAddInherit().
       */
      if (TRIGGER_FOR_ROW(tgtype) && has_superclass(rel->rd_id))
      {
        /* Use appropriate error message. */
        if (rel->rd_rel->relispartition)
          ereport(ERROR,
              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
               errmsg("ROW triggers with transition tables are not supported on partitions")));
        else
          ereport(ERROR,
              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
               errmsg("ROW triggers with transition tables are not supported on inheritance children")));
      }

      if (stmt->timing != TRIGGER_TYPE_AFTER)
        ereport(ERROR,
            (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
             errmsg("transition table name can only be specified for an AFTER trigger")));

      if (TRIGGER_FOR_TRUNCATE(tgtype))
        ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("TRUNCATE triggers with transition tables are not supported")));

      /*
       * We currently don't allow multi-event triggers ("INSERT OR
       * UPDATE") with transition tables, because it's not clear how to
       * handle INSERT ... ON CONFLICT statements which can fire both
       * INSERT and UPDATE triggers.  We show the inserted tuples to
       * INSERT triggers and the updated tuples to UPDATE triggers, but
       * it's not yet clear what INSERT OR UPDATE trigger should see.
       * This restriction could be lifted if we can decide on the right
       * semantics in a later release.
       */
      if (((TRIGGER_FOR_INSERT(tgtype) ? 1 : 0) +
         (TRIGGER_FOR_UPDATE(tgtype) ? 1 : 0) +
         (TRIGGER_FOR_DELETE(tgtype) ? 1 : 0)) != 1)
        ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("transition tables cannot be specified for triggers with more than one event")));

      /*
       * We currently don't allow column-specific triggers with
       * transition tables.  Per spec, that seems to require
       * accumulating separate transition tables for each combination of
       * columns, which is a lot of work for a rather marginal feature.
       */
      if (stmt->columns != NIL)
        ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("transition tables cannot be specified for triggers with column lists")));

      /*
       * We disallow constraint triggers with transition tables, to
       * protect the assumption that such triggers can't be deferred.
       * See notes with AfterTriggers data structures, below.
       *
       * Currently this is enforced by the grammar, so just Assert here.
       */
      Assert(!stmt->isconstraint);

      if (tt->isNew)
      {
        if (!(TRIGGER_FOR_INSERT(tgtype) ||
            TRIGGER_FOR_UPDATE(tgtype)))
          ereport(ERROR,
              (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
               errmsg("NEW TABLE can only be specified for an INSERT or UPDATE trigger")));

        if (newtablename != NULL)
          ereport(ERROR,
              (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
               errmsg("NEW TABLE cannot be specified multiple times")));

        newtablename = tt->name;
      }
      else
      {
        if (!(TRIGGER_FOR_DELETE(tgtype) ||
            TRIGGER_FOR_UPDATE(tgtype)))
          ereport(ERROR,
              (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
               errmsg("OLD TABLE can only be specified for a DELETE or UPDATE trigger")));

        if (oldtablename != NULL)
          ereport(ERROR,
              (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
               errmsg("OLD TABLE cannot be specified multiple times")));

        oldtablename = tt->name;
      }
    }

    if (newtablename != NULL && oldtablename != NULL &&
      strcmp(newtablename, oldtablename) == 0)
      ereport(ERROR,
          (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
           errmsg("OLD TABLE name and NEW TABLE name cannot be the same")));
  }

  /*
   * Parse the WHEN clause, if any and we weren't passed an already
   * transformed one.
   *
   * Note that as a side effect, we fill whenRtable when parsing.  If we got
   * an already parsed clause, this does not occur, which is what we want --
   * no point in adding redundant dependencies below.
   */
  if (!whenClause && stmt->whenClause)
  {
    ParseState *pstate;
    ParseNamespaceItem *nsitem;
    List     *varList;
    ListCell   *lc;

    /* Set up a pstate to parse with */
    pstate = make_parsestate(NULL);
    pstate->p_sourcetext = queryString;

    /*
     * Set up nsitems for OLD and NEW references.
     *
     * 'OLD' must always have varno equal to 1 and 'NEW' equal to 2.
     */
    nsitem = addRangeTableEntryForRelation(pstate, rel,
                         AccessShareLock,
                         makeAlias("old", NIL),
                         false, false);
    addNSItemToQuery(pstate, nsitem, false, true, true);
    nsitem = addRangeTableEntryForRelation(pstate, rel,
                         AccessShareLock,
                         makeAlias("new", NIL),
                         false, false);
    addNSItemToQuery(pstate, nsitem, false, true, true);

    /* Transform expression.  Copy to be sure we don't modify original */
    whenClause = transformWhereClause(pstate,
                      copyObject(stmt->whenClause),
                      EXPR_KIND_TRIGGER_WHEN,
                      "WHEN");
    /* we have to fix its collations too */
    assign_expr_collations(pstate, whenClause);

    /*
     * Check for disallowed references to OLD/NEW.
     *
     * NB: pull_var_clause is okay here only because we don't allow
     * subselects in WHEN clauses; it would fail to examine the contents
     * of subselects.
     */
    varList = pull_var_clause(whenClause, 0);
    foreach(lc, varList)
    {
      Var      *var = (Var *) lfirst(lc);

      switch (var->varno)
      {
        case PRS2_OLD_VARNO:
          if (!TRIGGER_FOR_ROW(tgtype))
            ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("statement trigger's WHEN condition cannot reference column values"),
                 parser_errposition(pstate, var->location)));
          if (TRIGGER_FOR_INSERT(tgtype))
            ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("INSERT trigger's WHEN condition cannot reference OLD values"),
                 parser_errposition(pstate, var->location)));
          /* system columns are okay here */
          break;
        case PRS2_NEW_VARNO:
          if (!TRIGGER_FOR_ROW(tgtype))
            ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("statement trigger's WHEN condition cannot reference column values"),
                 parser_errposition(pstate, var->location)));
          if (TRIGGER_FOR_DELETE(tgtype))
            ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("DELETE trigger's WHEN condition cannot reference NEW values"),
                 parser_errposition(pstate, var->location)));
          if (var->varattno < 0 && TRIGGER_FOR_BEFORE(tgtype))
            ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("BEFORE trigger's WHEN condition cannot reference NEW system columns"),
                 parser_errposition(pstate, var->location)));
          if (TRIGGER_FOR_BEFORE(tgtype) &&
            var->varattno == 0 &&
            RelationGetDescr(rel)->constr &&
            (RelationGetDescr(rel)->constr->has_generated_stored ||
             RelationGetDescr(rel)->constr->has_generated_virtual))
            ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("BEFORE trigger's WHEN condition cannot reference NEW generated columns"),
                 errdetail("A whole-row reference is used and the table contains generated columns."),
                 parser_errposition(pstate, var->location)));
          if (TRIGGER_FOR_BEFORE(tgtype) &&
            var->varattno > 0 &&
            TupleDescAttr(RelationGetDescr(rel), var->varattno - 1)->attgenerated)
            ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("BEFORE trigger's WHEN condition cannot reference NEW generated columns"),
                 errdetail("Column \"%s\" is a generated column.",
                       NameStr(TupleDescAttr(RelationGetDescr(rel), var->varattno - 1)->attname)),
                 parser_errposition(pstate, var->location)));
          break;
        default:
          /* can't happen without add_missing_from, so just elog */
          elog(ERROR, "trigger WHEN condition cannot contain references to other relations");
          break;
      }
    }

    /* we'll need the rtable for recordDependencyOnExpr */
    whenRtable = pstate->p_rtable;

    qual = nodeToString(whenClause);

    free_parsestate(pstate);
  }
  else if (!whenClause)
  {
    whenClause = NULL;
    whenRtable = NIL;
    qual = NULL;
  }
  else
  {
    qual = nodeToString(whenClause);
    whenRtable = NIL;
  }

  /*
   * Find and validate the trigger function.
   */
  if (!OidIsValid(funcoid))
    funcoid = LookupFuncName(stmt->funcname, 0, NULL, false);
  if (!isInternal)
  {
    aclresult = object_aclcheck(ProcedureRelationId, funcoid, GetUserId(), ACL_EXECUTE);
    if (aclresult != ACLCHECK_OK)
      aclcheck_error(aclresult, OBJECT_FUNCTION,
               NameListToString(stmt->funcname));
  }
  funcrettype = get_func_rettype(funcoid);
  if (funcrettype != TRIGGEROID)
    ereport(ERROR,
        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
         errmsg("function %s must return type %s",
            NameListToString(stmt->funcname), "trigger")));

  /*
   * Scan pg_trigger to see if there is already a trigger of the same name.
   * Skip this for internally generated triggers, since we'll modify the
   * name to be unique below.
   *
   * NOTE that this is cool only because we have ShareRowExclusiveLock on
   * the relation, so the trigger set won't be changing underneath us.
   */
  tgrel = table_open(TriggerRelationId, RowExclusiveLock);
  if (!isInternal)
  {
    ScanKeyData skeys[2];
    SysScanDesc tgscan;

    ScanKeyInit(&skeys[0],
          Anum_pg_trigger_tgrelid,
          BTEqualStrategyNumber, F_OIDEQ,
          ObjectIdGetDatum(RelationGetRelid(rel)));

    ScanKeyInit(&skeys[1],
          Anum_pg_trigger_tgname,
          BTEqualStrategyNumber, F_NAMEEQ,
          CStringGetDatum(stmt->trigname));

    tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
                  NULL, 2, skeys);

    /* There should be at most one matching tuple */
    if (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
    {
      Form_pg_trigger oldtrigger = (Form_pg_trigger) GETSTRUCT(tuple);

      trigoid = oldtrigger->oid;
      existing_constraint_oid = oldtrigger->tgconstraint;
      existing_isInternal = oldtrigger->tgisinternal;
      existing_isClone = OidIsValid(oldtrigger->tgparentid);
      trigger_exists = true;
      /* copy the tuple to use in CatalogTupleUpdate() */
      tuple = heap_copytuple(tuple);
    }
    systable_endscan(tgscan);
  }

  if (!trigger_exists)
  {
    /* Generate the OID for the new trigger. */
    trigoid = GetNewOidWithIndex(tgrel, TriggerOidIndexId,
                   Anum_pg_trigger_oid);
  }
  else
  {
    /*
     * If OR REPLACE was specified, we'll replace the old trigger;
     * otherwise complain about the duplicate name.
     */
    if (!stmt->replace)
      ereport(ERROR,
          (errcode(ERRCODE_DUPLICATE_OBJECT),
           errmsg("trigger \"%s\" for relation \"%s\" already exists",
              stmt->trigname, RelationGetRelationName(rel))));

    /*
     * An internal trigger or a child trigger (isClone) cannot be replaced
     * by a user-defined trigger.  However, skip this test when
     * in_partition, because then we're recursing from a partitioned table
     * and the check was made at the parent level.
     */
    if ((existing_isInternal || existing_isClone) &&
      !isInternal && !in_partition)
      ereport(ERROR,
          (errcode(ERRCODE_DUPLICATE_OBJECT),
           errmsg("trigger \"%s\" for relation \"%s\" is an internal or a child trigger",
              stmt->trigname, RelationGetRelationName(rel))));

    /*
     * It is not allowed to replace with a constraint trigger; gram.y
     * should have enforced this already.
     */
    Assert(!stmt->isconstraint);

    /*
     * It is not allowed to replace an existing constraint trigger,
     * either.  (The reason for these restrictions is partly that it seems
     * difficult to deal with pending trigger events in such cases, and
     * partly that the command might imply changing the constraint's
     * properties as well, which doesn't seem nice.)
     */
    if (OidIsValid(existing_constraint_oid))
      ereport(ERROR,
          (errcode(ERRCODE_DUPLICATE_OBJECT),
           errmsg("trigger \"%s\" for relation \"%s\" is a constraint trigger",
              stmt->trigname, RelationGetRelationName(rel))));
  }

  /*
   * If it's a user-entered CREATE CONSTRAINT TRIGGER command, make a
   * corresponding pg_constraint entry.
   */
  if (stmt->isconstraint && !OidIsValid(constraintOid))
  {
    /* Internal callers should have made their own constraints */
    Assert(!isInternal);
    constraintOid = CreateConstraintEntry(stmt->trigname,
                        RelationGetNamespace(rel),
                        CONSTRAINT_TRIGGER,
                        stmt->deferrable,
                        stmt->initdeferred,
                        true, /* Is Enforced */
                        true,
                        InvalidOid, /* no parent */
                        RelationGetRelid(rel),
                        NULL, /* no conkey */
                        0,
                        0,
                        InvalidOid, /* no domain */
                        InvalidOid, /* no index */
                        InvalidOid, /* no foreign key */
                        NULL,
                        NULL,
                        NULL,
                        NULL,
                        0,
                        ' ',
                        ' ',
                        NULL,
                        0,
                        ' ',
                        NULL, /* no exclusion */
                        NULL, /* no check constraint */
                        NULL,
                        true, /* islocal */
                        0,  /* inhcount */
                        true, /* noinherit */
                        false,  /* conperiod */
                        isInternal);  /* is_internal */
  }

  /*
   * If trigger is internally generated, modify the provided trigger name to
   * ensure uniqueness by appending the trigger OID.  (Callers will usually
   * supply a simple constant trigger name in these cases.)
   */
  if (isInternal)
  {
    snprintf(internaltrigname, sizeof(internaltrigname),
         "%s_%u", stmt->trigname, trigoid);
    trigname = internaltrigname;
  }
  else
  {
    /* user-defined trigger; use the specified trigger name as-is */
    trigname = stmt->trigname;
  }

  /*
   * Build the new pg_trigger tuple.
   */
  memset(nulls, false, sizeof(nulls));

  values[Anum_pg_trigger_oid - 1] = ObjectIdGetDatum(trigoid);
  values[Anum_pg_trigger_tgrelid - 1] = ObjectIdGetDatum(RelationGetRelid(rel));
  values[Anum_pg_trigger_tgparentid - 1] = ObjectIdGetDatum(parentTriggerOid);
  values[Anum_pg_trigger_tgname - 1] = DirectFunctionCall1(namein,
                               CStringGetDatum(trigname));
  values[Anum_pg_trigger_tgfoid - 1] = ObjectIdGetDatum(funcoid);
  values[Anum_pg_trigger_tgtype - 1] = Int16GetDatum(tgtype);
  values[Anum_pg_trigger_tgenabled - 1] = CharGetDatum(trigger_fires_when);
  values[Anum_pg_trigger_tgisinternal - 1] = BoolGetDatum(isInternal);
  values[Anum_pg_trigger_tgconstrrelid - 1] = ObjectIdGetDatum(constrrelid);
  values[Anum_pg_trigger_tgconstrindid - 1] = ObjectIdGetDatum(indexOid);
  values[Anum_pg_trigger_tgconstraint - 1] = ObjectIdGetDatum(constraintOid);
  values[Anum_pg_trigger_tgdeferrable - 1] = BoolGetDatum(stmt->deferrable);
  values[Anum_pg_trigger_tginitdeferred - 1] = BoolGetDatum(stmt->initdeferred);

  if (stmt->args)
  {
    ListCell   *le;
    char     *args;
    int16   nargs = list_length(stmt->args);
    int     len = 0;

    foreach(le, stmt->args)
    {
      char     *ar = strVal(lfirst(le));

      len += strlen(ar) + 4;
      for (; *ar; ar++)
      {
        if (*ar == '\\')
          len++;
      }
    }
    args = (char *) palloc(len + 1);
    args[0] = '\0';
    foreach(le, stmt->args)
    {
      char     *s = strVal(lfirst(le));
      char     *d = args + strlen(args);

      while (*s)
      {
        if (*s == '\\')
          *d++ = '\\';
        *d++ = *s++;
      }
      strcpy(d, "\\000");
    }
    values[Anum_pg_trigger_tgnargs - 1] = Int16GetDatum(nargs);
    values[Anum_pg_trigger_tgargs - 1] = DirectFunctionCall1(byteain,
                                 CStringGetDatum(args));
  }
  else
  {
    values[Anum_pg_trigger_tgnargs - 1] = Int16GetDatum(0);
    values[Anum_pg_trigger_tgargs - 1] = DirectFunctionCall1(byteain,
                                 CStringGetDatum(""));
  }

  /* build column number array if it's a column-specific trigger */
  ncolumns = list_length(stmt->columns);
  if (ncolumns == 0)
    columns = NULL;
  else
  {
    ListCell   *cell;
    int     i = 0;

    columns = (int16 *) palloc(ncolumns * sizeof(int16));
    foreach(cell, stmt->columns)
    {
      char     *name = strVal(lfirst(cell));
      int16   attnum;
      int     j;

      /* Lookup column name.  System columns are not allowed */
      attnum = attnameAttNum(rel, name, false);
      if (attnum == InvalidAttrNumber)
        ereport(ERROR,
            (errcode(ERRCODE_UNDEFINED_COLUMN),
             errmsg("column \"%s\" of relation \"%s\" does not exist",
                name, RelationGetRelationName(rel))));

      /* Check for duplicates */
      for (j = i - 1; j >= 0; j--)
      {
        if (columns[j] == attnum)
          ereport(ERROR,
              (errcode(ERRCODE_DUPLICATE_COLUMN),
               errmsg("column \"%s\" specified more than once",
                  name)));
      }

      columns[i++] = attnum;
    }
  }
  tgattr = buildint2vector(columns, ncolumns);
  values[Anum_pg_trigger_tgattr - 1] = PointerGetDatum(tgattr);

  /* set tgqual if trigger has WHEN clause */
  if (qual)
    values[Anum_pg_trigger_tgqual - 1] = CStringGetTextDatum(qual);
  else
    nulls[Anum_pg_trigger_tgqual - 1] = true;

  if (oldtablename)
    values[Anum_pg_trigger_tgoldtable - 1] = DirectFunctionCall1(namein,
                                   CStringGetDatum(oldtablename));
  else
    nulls[Anum_pg_trigger_tgoldtable - 1] = true;
  if (newtablename)
    values[Anum_pg_trigger_tgnewtable - 1] = DirectFunctionCall1(namein,
                                   CStringGetDatum(newtablename));
  else
    nulls[Anum_pg_trigger_tgnewtable - 1] = true;

  /*
   * Insert or replace tuple in pg_trigger.
   */
  if (!trigger_exists)
  {
    tuple = heap_form_tuple(tgrel->rd_att, values, nulls);
    CatalogTupleInsert(tgrel, tuple);
  }
  else
  {
    HeapTuple newtup;

    newtup = heap_form_tuple(tgrel->rd_att, values, nulls);
    CatalogTupleUpdate(tgrel, &tuple->t_self, newtup);
    heap_freetuple(newtup);
  }

  heap_freetuple(tuple);    /* free either original or new tuple */
  table_close(tgrel, RowExclusiveLock);

  pfree(DatumGetPointer(values[Anum_pg_trigger_tgname - 1]));
  pfree(DatumGetPointer(values[Anum_pg_trigger_tgargs - 1]));
  pfree(DatumGetPointer(values[Anum_pg_trigger_tgattr - 1]));
  if (oldtablename)
    pfree(DatumGetPointer(values[Anum_pg_trigger_tgoldtable - 1]));
  if (newtablename)
    pfree(DatumGetPointer(values[Anum_pg_trigger_tgnewtable - 1]));

  /*
   * Update relation's pg_class entry; if necessary; and if not, send an SI
   * message to make other backends (and this one) rebuild relcache entries.
   */
  pgrel = table_open(RelationRelationId, RowExclusiveLock);
  tuple = SearchSysCacheCopy1(RELOID,
                ObjectIdGetDatum(RelationGetRelid(rel)));
  if (!HeapTupleIsValid(tuple))
    elog(ERROR, "cache lookup failed for relation %u",
       RelationGetRelid(rel));
  if (!((Form_pg_class) GETSTRUCT(tuple))->relhastriggers)
  {
    ((Form_pg_class) GETSTRUCT(tuple))->relhastriggers = true;

    CatalogTupleUpdate(pgrel, &tuple->t_self, tuple);

    CommandCounterIncrement();
  }
  else
    CacheInvalidateRelcacheByTuple(tuple);

  heap_freetuple(tuple);
  table_close(pgrel, RowExclusiveLock);

  /*
   * If we're replacing a trigger, flush all the old dependencies before
   * recording new ones.
   */
  if (trigger_exists)
    deleteDependencyRecordsFor(TriggerRelationId, trigoid, true);

  /*
   * Record dependencies for trigger.  Always place a normal dependency on
   * the function.
   */
  myself.classId = TriggerRelationId;
  myself.objectId = trigoid;
  myself.objectSubId = 0;

  referenced.classId = ProcedureRelationId;
  referenced.objectId = funcoid;
  referenced.objectSubId = 0;
  recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);

  if (isInternal && OidIsValid(constraintOid))
  {
    /*
     * Internally-generated trigger for a constraint, so make it an
     * internal dependency of the constraint.  We can skip depending on
     * the relation(s), as there'll be an indirect dependency via the
     * constraint.
     */
    referenced.classId = ConstraintRelationId;
    referenced.objectId = constraintOid;
    referenced.objectSubId = 0;
    recordDependencyOn(&myself, &referenced, DEPENDENCY_INTERNAL);
  }
  else
  {
    /*
     * User CREATE TRIGGER, so place dependencies.  We make trigger be
     * auto-dropped if its relation is dropped or if the FK relation is
     * dropped.  (Auto drop is compatible with our pre-7.3 behavior.)
     */
    referenced.classId = RelationRelationId;
    referenced.objectId = RelationGetRelid(rel);
    referenced.objectSubId = 0;
    recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);

    if (OidIsValid(constrrelid))
    {
      referenced.classId = RelationRelationId;
      referenced.objectId = constrrelid;
      referenced.objectSubId = 0;
      recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);
    }
    /* Not possible to have an index dependency in this case */
    Assert(!OidIsValid(indexOid));

    /*
     * If it's a user-specified constraint trigger, make the constraint
     * internally dependent on the trigger instead of vice versa.
     */
    if (OidIsValid(constraintOid))
    {
      referenced.classId = ConstraintRelationId;
      referenced.objectId = constraintOid;
      referenced.objectSubId = 0;
      recordDependencyOn(&referenced, &myself, DEPENDENCY_INTERNAL);
    }

    /*
     * If it's a partition trigger, create the partition dependencies.
     */
    if (OidIsValid(parentTriggerOid))
    {
      ObjectAddressSet(referenced, TriggerRelationId, parentTriggerOid);
      recordDependencyOn(&myself, &referenced, DEPENDENCY_PARTITION_PRI);
      ObjectAddressSet(referenced, RelationRelationId, RelationGetRelid(rel));
      recordDependencyOn(&myself, &referenced, DEPENDENCY_PARTITION_SEC);
    }
  }

  /* If column-specific trigger, add normal dependencies on columns */
  if (columns != NULL)
  {
    int     i;

    referenced.classId = RelationRelationId;
    referenced.objectId = RelationGetRelid(rel);
    for (i = 0; i < ncolumns; i++)
    {
      referenced.objectSubId = columns[i];
      recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }
  }

  /*
   * If it has a WHEN clause, add dependencies on objects mentioned in the
   * expression (eg, functions, as well as any columns used).
   */
  if (whenRtable != NIL)
  {
    if (!isInternal)
      CheckUsageOnTypesInExpr(whenClause, whenRtable, GetUserId());

    recordDependencyOnExpr(&myself, whenClause, whenRtable,
                 DEPENDENCY_NORMAL);
  }

  /* Post creation hook for new trigger */
  InvokeObjectPostCreateHookArg(TriggerRelationId, trigoid, 0,
                  isInternal);

  /*
   * Lastly, create the trigger on child relations, if needed.
   */
  if (partition_recurse)
  {
    PartitionDesc partdesc = RelationGetPartitionDesc(rel, true);
    int     i;
    MemoryContext oldcxt,
          perChildCxt;

    perChildCxt = AllocSetContextCreate(CurrentMemoryContext,
                      "part trig clone",
                      ALLOCSET_SMALL_SIZES);

    /*
     * We don't currently expect to be called with a valid indexOid.  If
     * that ever changes then we'll need to write code here to find the
     * corresponding child index.
     */
    Assert(!OidIsValid(indexOid));

    oldcxt = MemoryContextSwitchTo(perChildCxt);

    /* Iterate to create the trigger on each existing partition */
    for (i = 0; i < partdesc->nparts; i++)
    {
      CreateTrigStmt *childStmt;
      Relation  childTbl;
      Node     *qual;

      childTbl = table_open(partdesc->oids[i], ShareRowExclusiveLock);

      /*
       * Initialize our fabricated parse node by copying the original
       * one, then resetting fields that we pass separately.
       */
      childStmt = copyObject(stmt);
      childStmt->funcname = NIL;
      childStmt->whenClause = NULL;

      /* If there is a WHEN clause, create a modified copy of it */
      qual = copyObject(whenClause);
      qual = (Node *)
        map_partition_varattnos((List *) qual, PRS2_OLD_VARNO,
                    childTbl, rel);
      qual = (Node *)
        map_partition_varattnos((List *) qual, PRS2_NEW_VARNO,
                    childTbl, rel);

      CreateTriggerFiringOn(childStmt, queryString,
                  partdesc->oids[i], refRelOid,
                  InvalidOid, InvalidOid,
                  funcoid, trigoid, qual,
                  isInternal, true, trigger_fires_when);

      table_close(childTbl, NoLock);

      MemoryContextReset(perChildCxt);
    }

    MemoryContextSwitchTo(oldcxt);
    MemoryContextDelete(perChildCxt);
  }

  /* Keep lock on target rel until end of xact */
  table_close(rel, NoLock);

  return myself;
}

/*
 * TriggerSetParentTrigger
 *    Set a partition's trigger as child of its parent trigger,
 *    or remove the linkage if parentTrigId is InvalidOid.
 *
 * This updates the constraint's pg_trigger row to show it as inherited, and
 * adds PARTITION dependencies to prevent the trigger from being deleted
 * on its own.  Alternatively, reverse that.
 */
void
TriggerSetParentTrigger(Relation trigRel,
            Oid childTrigId,
            Oid parentTrigId,
            Oid childTableId)
{
  SysScanDesc tgscan;
  ScanKeyData skey[1];
  Form_pg_trigger trigForm;
  HeapTuple tuple,
        newtup;
  ObjectAddress depender;
  ObjectAddress referenced;

  /*
   * Find the trigger to delete.
   */
  ScanKeyInit(&skey[0],
        Anum_pg_trigger_oid,
        BTEqualStrategyNumber, F_OIDEQ,
        ObjectIdGetDatum(childTrigId));

  tgscan = systable_beginscan(trigRel, TriggerOidIndexId, true,
                NULL, 1, skey);

  tuple = systable_getnext(tgscan);
  if (!HeapTupleIsValid(tuple))
    elog(ERROR, "could not find tuple for trigger %u", childTrigId);
  newtup = heap_copytuple(tuple);
  trigForm = (Form_pg_trigger) GETSTRUCT(newtup);
  if (OidIsValid(parentTrigId))
  {
    /* don't allow setting parent for a constraint that already has one */
    if (OidIsValid(trigForm->tgparentid))
      elog(ERROR, "trigger %u already has a parent trigger",
         childTrigId);

    trigForm->tgparentid = parentTrigId;

    CatalogTupleUpdate(trigRel, &tuple->t_self, newtup);

    ObjectAddressSet(depender, TriggerRelationId, childTrigId);

    ObjectAddressSet(referenced, TriggerRelationId, parentTrigId);
    recordDependencyOn(&depender, &referenced, DEPENDENCY_PARTITION_PRI);

    ObjectAddressSet(referenced, RelationRelationId, childTableId);
    recordDependencyOn(&depender, &referenced, DEPENDENCY_PARTITION_SEC);
  }
  else
  {
    trigForm->tgparentid = InvalidOid;

    CatalogTupleUpdate(trigRel, &tuple->t_self, newtup);

    deleteDependencyRecordsForClass(TriggerRelationId, childTrigId,
                    TriggerRelationId,
                    DEPENDENCY_PARTITION_PRI);
    deleteDependencyRecordsForClass(TriggerRelationId, childTrigId,
                    RelationRelationId,
                    DEPENDENCY_PARTITION_SEC);
  }

  heap_freetuple(newtup);
  systable_endscan(tgscan);
}


/*
 * Guts of trigger deletion.
 */
void
RemoveTriggerById(Oid trigOid)
{
  Relation  tgrel;
  SysScanDesc tgscan;
  ScanKeyData skey[1];
  HeapTuple tup;
  Oid     relid;
  Relation  rel;

  tgrel = table_open(TriggerRelationId, RowExclusiveLock);

  /*
   * Find the trigger to delete.
   */
  ScanKeyInit(&skey[0],
        Anum_pg_trigger_oid,
        BTEqualStrategyNumber, F_OIDEQ,
        ObjectIdGetDatum(trigOid));

  tgscan = systable_beginscan(tgrel, TriggerOidIndexId, true,
                NULL, 1, skey);

  tup = systable_getnext(tgscan);
  if (!HeapTupleIsValid(tup))
    elog(ERROR, "could not find tuple for trigger %u", trigOid);

  /*
   * Open and exclusive-lock the relation the trigger belongs to.
   */
  relid = ((Form_pg_trigger) GETSTRUCT(tup))->tgrelid;

  rel = table_open(relid, AccessExclusiveLock);

  if (rel->rd_rel->relkind != RELKIND_RELATION &&
    rel->rd_rel->relkind != RELKIND_VIEW &&
    rel->rd_rel->relkind != RELKIND_FOREIGN_TABLE &&
    rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
    ereport(ERROR,
        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
         errmsg("relation \"%s\" cannot have triggers",
            RelationGetRelationName(rel)),
         errdetail_relkind_not_supported(rel->rd_rel->relkind)));

  if (!allowSystemTableMods && IsSystemRelation(rel))
    ereport(ERROR,
        (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
         errmsg("permission denied: \"%s\" is a system catalog",
            RelationGetRelationName(rel))));

  /*
   * Delete the pg_trigger tuple.
   */
  CatalogTupleDelete(tgrel, &tup->t_self);

  systable_endscan(tgscan);
  table_close(tgrel, RowExclusiveLock);

  /*
   * We do not bother to try to determine whether any other triggers remain,
   * which would be needed in order to decide whether it's safe to clear the
   * relation's relhastriggers.  (In any case, there might be a concurrent
   * process adding new triggers.)  Instead, just force a relcache inval to
   * make other backends (and this one too!) rebuild their relcache entries.
   * There's no great harm in leaving relhastriggers true even if there are
   * no triggers left.
   */
  CacheInvalidateRelcache(rel);

  /* Keep lock on trigger's rel until end of xact */
  table_close(rel, NoLock);
}

/*
 * get_trigger_oid - Look up a trigger by name to find its OID.
 *
 * If missing_ok is false, throw an error if trigger not found.  If
 * true, just return InvalidOid.
 */
Oid
get_trigger_oid(Oid relid, const char *trigname, bool missing_ok)
{
  Relation  tgrel;
  ScanKeyData skey[2];
  SysScanDesc tgscan;
  HeapTuple tup;
  Oid     oid;

  /*
   * Find the trigger, verify permissions, set up object address
   */
  tgrel = table_open(TriggerRelationId, AccessShareLock);

  ScanKeyInit(&skey[0],
        Anum_pg_trigger_tgrelid,
        BTEqualStrategyNumber, F_OIDEQ,
        ObjectIdGetDatum(relid));
  ScanKeyInit(&skey[1],
        Anum_pg_trigger_tgname,
        BTEqualStrategyNumber, F_NAMEEQ,
        CStringGetDatum(trigname));

  tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
                NULL, 2, skey);

  tup = systable_getnext(tgscan);

  if (!HeapTupleIsValid(tup))
  {
    if (!missing_ok)
      ereport(ERROR,
          (errcode(ERRCODE_UNDEFINED_OBJECT),
           errmsg("trigger \"%s\" for table \"%s\" does not exist",
              trigname, get_rel_name(relid))));
    oid = InvalidOid;
  }
  else
  {
    oid = ((Form_pg_trigger) GETSTRUCT(tup))->oid;
  }

  systable_endscan(tgscan);
  table_close(tgrel, AccessShareLock);
  return oid;
}

/*
 * Perform permissions and integrity checks before acquiring a relation lock.
 */
static void
RangeVarCallbackForRenameTrigger(const RangeVar *rv, Oid relid, Oid oldrelid,
                 void *arg)
{
  HeapTuple tuple;
  Form_pg_class form;

  tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
  if (!HeapTupleIsValid(tuple))
    return;         /* concurrently dropped */
  form = (Form_pg_class) GETSTRUCT(tuple);

  /* only tables and views can have triggers */
  if (form->relkind != RELKIND_RELATION && form->relkind != RELKIND_VIEW &&
    form->relkind != RELKIND_FOREIGN_TABLE &&
    form->relkind != RELKIND_PARTITIONED_TABLE)
    ereport(ERROR,
        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
         errmsg("relation \"%s\" cannot have triggers",
            rv->relname),
         errdetail_relkind_not_supported(form->relkind)));

  /* you must own the table to rename one of its triggers */
  if (!object_ownercheck(RelationRelationId, relid, GetUserId()))
    aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relid)), rv->relname);

  /*
   * Conflict log tables are used internally for logical replication
   * conflict logging and should not have triggers, as it could disrupt
   * conflict logging.
   */
  if (IsConflictLogTableClass(form))
    ereport(ERROR,
        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
         errmsg("cannot rename trigger on conflict log table \"%s\"",
            rv->relname),
         errdetail("Conflict log tables are system-managed tables for logical replication conflicts.")));

  if (!allowSystemTableMods && IsSystemClass(relid, form))
    ereport(ERROR,
        (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
         errmsg("permission denied: \"%s\" is a system catalog",
            rv->relname)));

  ReleaseSysCache(tuple);
}

/*
 *    renametrig    - changes the name of a trigger on a relation
 *
 *    trigger name is changed in trigger catalog.
 *    No record of the previous name is kept.
 *
 *    get proper relrelation from relation catalog (if not arg)
 *    scan trigger catalog
 *        for name conflict (within rel)
 *        for original trigger (if not arg)
 *    modify tgname in trigger tuple
 *    update row in catalog
 */
ObjectAddress
renametrig(RenameStmt *stmt)
{
  Oid     tgoid;
  Relation  targetrel;
  Relation  tgrel;
  HeapTuple tuple;
  SysScanDesc tgscan;
  ScanKeyData key[2];
  Oid     relid;
  ObjectAddress address;

  /*
   * Look up name, check permissions, and acquire lock (which we will NOT
   * release until end of transaction).
   */
  relid = RangeVarGetRelidExtended(stmt->relation, AccessExclusiveLock,
                   0,
                   RangeVarCallbackForRenameTrigger,
                   NULL);

  /* Have lock already, so just need to build relcache entry. */
  targetrel = relation_open(relid, NoLock);

  /*
   * On partitioned tables, this operation recurses to partitions.  Lock all
   * tables upfront.
   */
  if (targetrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    (void) find_all_inheritors(relid, AccessExclusiveLock, NULL);

  tgrel = table_open(TriggerRelationId, RowExclusiveLock);

  /*
   * Search for the trigger to modify.
   */
  ScanKeyInit(&key[0],
        Anum_pg_trigger_tgrelid,
        BTEqualStrategyNumber, F_OIDEQ,
        ObjectIdGetDatum(relid));
  ScanKeyInit(&key[1],
        Anum_pg_trigger_tgname,
        BTEqualStrategyNumber, F_NAMEEQ,
        PointerGetDatum(stmt->subname));
  tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
                NULL, 2, key);
  if (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
  {
    Form_pg_trigger trigform;

    trigform = (Form_pg_trigger) GETSTRUCT(tuple);
    tgoid = trigform->oid;

    /*
     * If the trigger descends from a trigger on a parent partitioned
     * table, reject the rename.  We don't allow a trigger in a partition
     * to differ in name from that of its parent: that would lead to an
     * inconsistency that pg_dump would not reproduce.
     */
    if (OidIsValid(trigform->tgparentid))
      ereport(ERROR,
          errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
          errmsg("cannot rename trigger \"%s\" on table \"%s\"",
               stmt->subname, RelationGetRelationName(targetrel)),
          errhint("Rename the trigger on the partitioned table \"%s\" instead.",
              get_rel_name(get_partition_parent(relid, false))));


    /* Rename the trigger on this relation ... */
    renametrig_internal(tgrel, targetrel, tuple, stmt->newname,
              stmt->subname);

    /* ... and if it is partitioned, recurse to its partitions */
    if (targetrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
      PartitionDesc partdesc = RelationGetPartitionDesc(targetrel, true);

      for (int i = 0; i < partdesc->nparts; i++)
      {
        Oid     partitionId = partdesc->oids[i];

        renametrig_partition(tgrel, partitionId, trigform->oid,
                   stmt->newname, stmt->subname);
      }
    }
  }
  else
  {
    ereport(ERROR,
        (errcode(ERRCODE_UNDEFINED_OBJECT),
         errmsg("trigger \"%s\" for table \"%s\" does not exist",
            stmt->subname, RelationGetRelationName(targetrel))));
  }

  ObjectAddressSet(address, TriggerRelationId, tgoid);

  systable_endscan(tgscan);

  table_close(tgrel, RowExclusiveLock);

  /*
   * Close rel, but keep exclusive lock!
   */
  relation_close(targetrel, NoLock);

  return address;
}

/*
 * Subroutine for renametrig -- perform the actual work of renaming one
 * trigger on one table.
 *
 * If the trigger has a name different from the expected one, raise a
 * NOTICE about it.
 */
static void
renametrig_internal(Relation tgrel, Relation targetrel, HeapTuple trigtup,
          const char *newname, const char *expected_name)
{
  HeapTuple tuple;
  Form_pg_trigger tgform;
  ScanKeyData key[2];
  SysScanDesc tgscan;

  /* If the trigger already has the new name, nothing to do. */
  tgform = (Form_pg_trigger) GETSTRUCT(trigtup);
  if (strcmp(NameStr(tgform->tgname), newname) == 0)
    return;

  /*
   * Before actually trying the rename, search for triggers with the same
   * name.  The update would fail with an ugly message in that case, and it
   * is better to throw a nicer error.
   */
  ScanKeyInit(&key[0],
        Anum_pg_trigger_tgrelid,
        BTEqualStrategyNumber, F_OIDEQ,
        ObjectIdGetDatum(RelationGetRelid(targetrel)));
  ScanKeyInit(&key[1],
        Anum_pg_trigger_tgname,
        BTEqualStrategyNumber, F_NAMEEQ,
        PointerGetDatum(newname));
  tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
                NULL, 2, key);
  if (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
    ereport(ERROR,
        (errcode(ERRCODE_DUPLICATE_OBJECT),
         errmsg("trigger \"%s\" for relation \"%s\" already exists",
            newname, RelationGetRelationName(targetrel))));
  systable_endscan(tgscan);

  /*
   * The target name is free; update the existing pg_trigger tuple with it.
   */
  tuple = heap_copytuple(trigtup);  /* need a modifiable copy */
  tgform = (Form_pg_trigger) GETSTRUCT(tuple);

  /*
   * If the trigger has a name different from what we expected, let the user
   * know. (We can proceed anyway, since we must have reached here following
   * a tgparentid link.)
   */
  if (strcmp(NameStr(tgform->tgname), expected_name) != 0)
    ereport(NOTICE,
        errmsg("renamed trigger \"%s\" on relation \"%s\"",
             NameStr(tgform->tgname),
             RelationGetRelationName(targetrel)));

  namestrcpy(&tgform->tgname, newname);

  CatalogTupleUpdate(tgrel, &tuple->t_self, tuple);

  InvokeObjectPostAlterHook(TriggerRelationId, tgform->oid, 0);

  /*
   * Invalidate relation's relcache entry so that other backends (and this
   * one too!) are sent SI message to make them rebuild relcache entries.
   * (Ideally this should happen automatically...)
   */
  CacheInvalidateRelcache(targetrel);
}

/*
 * Subroutine for renametrig -- Helper for recursing to partitions when
 * renaming triggers on a partitioned table.
 */
static void
renametrig_partition(Relation tgrel, Oid partitionId, Oid parentTriggerOid,
           const char *newname, const char *expected_name)
{
  SysScanDesc tgscan;
  ScanKeyData key;
  HeapTuple tuple;

  /*
   * Given a relation and the OID of a trigger on parent relation, find the
   * corresponding trigger in the child and rename that trigger to the given
   * name.
   */
  ScanKeyInit(&key,
        Anum_pg_trigger_tgrelid,
        BTEqualStrategyNumber, F_OIDEQ,
        ObjectIdGetDatum(partitionId));
  tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
                NULL, 1, &key);
  while (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
  {
    Form_pg_trigger tgform = (Form_pg_trigger) GETSTRUCT(tuple);
    Relation  partitionRel;

    if (tgform->tgparentid != parentTriggerOid)
      continue;     /* not our trigger */

    partitionRel = table_open(partitionId, NoLock);

    /* Rename the trigger on this partition */
    renametrig_internal(tgrel, partitionRel, tuple, newname, expected_name);

    /* And if this relation is partitioned, recurse to its partitions */
    if (partitionRel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
      PartitionDesc partdesc = RelationGetPartitionDesc(partitionRel,
                                true);

      for (int i = 0; i < partdesc->nparts; i++)
      {
        Oid     partoid = partdesc->oids[i];

        renametrig_partition(tgrel, partoid, tgform->oid, newname,
                   NameStr(tgform->tgname));
      }
    }
    table_close(partitionRel, NoLock);

    /* There should be at most one matching tuple */
    break;
  }
  systable_endscan(tgscan);
}

/*
 * EnableDisableTrigger()
 *
 *  Called by ALTER TABLE ENABLE/DISABLE [ REPLICA | ALWAYS ] TRIGGER
 *  to change 'tgenabled' field for the specified trigger(s)
 *
 * rel: relation to process (caller must hold suitable lock on it)
 * tgname: name of trigger to process, or NULL to scan all triggers
 * tgparent: if not zero, process only triggers with this tgparentid
 * fires_when: new value for tgenabled field. In addition to generic
 *         enablement/disablement, this also defines when the trigger
 *         should be fired in session replication roles.
 * skip_system: if true, skip "system" triggers (constraint triggers)
 * recurse: if true, recurse to partitions
 *
 * Caller should have checked permissions for the table; here we also
 * enforce that superuser privilege is required to alter the state of
 * system triggers
 */
void
EnableDisableTrigger(Relation rel, const char *tgname, Oid tgparent,
           char fires_when, bool skip_system, bool recurse,
           LOCKMODE lockmode)
{
  Relation  tgrel;
  int     nkeys;
  ScanKeyData keys[2];
  SysScanDesc tgscan;
  HeapTuple tuple;
  bool    found;
  bool    changed;

  /* Scan the relevant entries in pg_triggers */
  tgrel = table_open(TriggerRelationId, RowExclusiveLock);

  ScanKeyInit(&keys[0],
        Anum_pg_trigger_tgrelid,
        BTEqualStrategyNumber, F_OIDEQ,
        ObjectIdGetDatum(RelationGetRelid(rel)));
  if (tgname)
  {
    ScanKeyInit(&keys[1],
          Anum_pg_trigger_tgname,
          BTEqualStrategyNumber, F_NAMEEQ,
          CStringGetDatum(tgname));
    nkeys = 2;
  }
  else
    nkeys = 1;

  tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
                NULL, nkeys, keys);

  found = changed = false;

  while (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
  {
    Form_pg_trigger oldtrig = (Form_pg_trigger) GETSTRUCT(tuple);

    if (OidIsValid(tgparent) && tgparent != oldtrig->tgparentid)
      continue;

    if (oldtrig->tgisinternal)
    {
      /* system trigger ... ok to process? */
      if (skip_system)
        continue;
      if (!superuser())
        ereport(ERROR,
            (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
             errmsg("permission denied: \"%s\" is a system trigger",
                NameStr(oldtrig->tgname))));
    }

    found = true;

    if (oldtrig->tgenabled != fires_when)
    {
      /* need to change this one ... make a copy to scribble on */
      HeapTuple newtup = heap_copytuple(tuple);
      Form_pg_trigger newtrig = (Form_pg_trigger) GETSTRUCT(newtup);

      newtrig->tgenabled = fires_when;

      CatalogTupleUpdate(tgrel, &newtup->t_self, newtup);

      heap_freetuple(newtup);

      changed = true;
    }

    /*
     * When altering FOR EACH ROW triggers on a partitioned table, do the
     * same on the partitions as well, unless ONLY is specified.
     *
     * Note that we recurse even if we didn't change the trigger above,
     * because the partitions' copy of the trigger may have a different
     * value of tgenabled than the parent's trigger and thus might need to
     * be changed.
     */
    if (recurse &&
      rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
      (TRIGGER_FOR_ROW(oldtrig->tgtype)))
    {
      PartitionDesc partdesc = RelationGetPartitionDesc(rel, true);
      int     i;

      for (i = 0; i < partdesc->nparts; i++)
      {
        Relation  part;

        part = relation_open(partdesc->oids[i], lockmode);
        /* Match on child triggers' tgparentid, not their name */
        EnableDisableTrigger(part, NULL, oldtrig->oid,
                   fires_when, skip_system, recurse,
                   lockmode);
        table_close(part, NoLock);  /* keep lock till commit */
      }
    }

    InvokeObjectPostAlterHook(TriggerRelationId,
                  oldtrig->oid, 0);
  }

  systable_endscan(tgscan);

  table_close(tgrel, RowExclusiveLock);

  if (tgname && !found)
    ereport(ERROR,
        (errcode(ERRCODE_UNDEFINED_OBJECT),
         errmsg("trigger \"%s\" for table \"%s\" does not exist",
            tgname, RelationGetRelationName(rel))));

  /*
   * If we changed anything, broadcast a SI inval message to force each
   * backend (including our own!) to rebuild relation's relcache entry.
   * Otherwise they will fail to apply the change promptly.
   */
  if (changed)
    CacheInvalidateRelcache(rel);
}


/*
 * Build trigger data to attach to the given relcache entry.
 *
 * Note that trigger data attached to a relcache entry must be stored in
 * CacheMemoryContext to ensure it survives as long as the relcache entry.
 * But we should be running in a less long-lived working context.  To avoid
 * leaking cache memory if this routine fails partway through, we build a
 * temporary TriggerDesc in working memory and then copy the completed
 * structure into cache memory.
 */
void
RelationBuildTriggers(Relation relation)
{
  TriggerDesc *trigdesc;
  int     numtrigs;
  int     maxtrigs;
  Trigger    *triggers;
  Relation  tgrel;
  ScanKeyData skey;
  SysScanDesc tgscan;
  HeapTuple htup;
  MemoryContext oldContext;
  int     i;

  /*
   * Allocate a working array to hold the triggers (the array is extended if
   * necessary)
   */
  maxtrigs = 16;
  triggers = (Trigger *) palloc(maxtrigs * sizeof(Trigger));
  numtrigs = 0;

  /*
   * Note: since we scan the triggers using TriggerRelidNameIndexId, we will
   * be reading the triggers in name order, except possibly during
   * emergency-recovery operations (ie, IgnoreSystemIndexes). This in turn
   * ensures that triggers will be fired in name order.
   */
  ScanKeyInit(&skey,
        Anum_pg_trigger_tgrelid,
        BTEqualStrategyNumber, F_OIDEQ,
        ObjectIdGetDatum(RelationGetRelid(relation)));

  tgrel = table_open(TriggerRelationId, AccessShareLock);
  tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
                NULL, 1, &skey);

  while (HeapTupleIsValid(htup = systable_getnext(tgscan)))
  {
    Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(htup);
    Trigger    *build;
    Datum   datum;
    bool    isnull;

    if (numtrigs >= maxtrigs)
    {
      maxtrigs *= 2;
      triggers = (Trigger *) repalloc(triggers, maxtrigs * sizeof(Trigger));
    }
    build = &(triggers[numtrigs]);

    build->tgoid = pg_trigger->oid;
    build->tgname = DatumGetCString(DirectFunctionCall1(nameout,
                              NameGetDatum(&pg_trigger->tgname)));
    build->tgfoid = pg_trigger->tgfoid;
    build->tgtype = pg_trigger->tgtype;
    build->tgenabled = pg_trigger->tgenabled;
    build->tgisinternal = pg_trigger->tgisinternal;
    build->tgisclone = OidIsValid(pg_trigger->tgparentid);
    build->tgconstrrelid = pg_trigger->tgconstrrelid;
    build->tgconstrindid = pg_trigger->tgconstrindid;
    build->tgconstraint = pg_trigger->tgconstraint;
    build->tgdeferrable = pg_trigger->tgdeferrable;
    build->tginitdeferred = pg_trigger->tginitdeferred;
    build->tgnargs = pg_trigger->tgnargs;
    /* tgattr is first var-width field, so OK to access directly */
    build->tgnattr = pg_trigger->tgattr.dim1;
    if (build->tgnattr > 0)
    {
      build->tgattr = (int16 *) palloc(build->tgnattr * sizeof(int16));
      memcpy(build->tgattr, &(pg_trigger->tgattr.values),
           build->tgnattr * sizeof(int16));
    }
    else
      build->tgattr = NULL;
    if (build->tgnargs > 0)
    {
      bytea    *val;
      char     *p;

      val = DatumGetByteaPP(fastgetattr(htup,
                        Anum_pg_trigger_tgargs,
                        tgrel->rd_att, &isnull));
      if (isnull)
        elog(ERROR, "tgargs is null in trigger for relation \"%s\"",
           RelationGetRelationName(relation));
      p = (char *) VARDATA_ANY(val);
      build->tgargs = (char **) palloc(build->tgnargs * sizeof(char *));
      for (i = 0; i < build->tgnargs; i++)
      {
        build->tgargs[i] = pstrdup(p);
        p += strlen(p) + 1;
      }
    }
    else
      build->tgargs = NULL;

    datum = fastgetattr(htup, Anum_pg_trigger_tgoldtable,
              tgrel->rd_att, &isnull);
    if (!isnull)
      build->tgoldtable =
        DatumGetCString(DirectFunctionCall1(nameout, datum));
    else
      build->tgoldtable = NULL;

    datum = fastgetattr(htup, Anum_pg_trigger_tgnewtable,
              tgrel->rd_att, &isnull);
    if (!isnull)
      build->tgnewtable =
        DatumGetCString(DirectFunctionCall1(nameout, datum));
    else
      build->tgnewtable = NULL;

    datum = fastgetattr(htup, Anum_pg_trigger_tgqual,
              tgrel->rd_att, &isnull);
    if (!isnull)
      build->tgqual = TextDatumGetCString(datum);
    else
      build->tgqual = NULL;

    numtrigs++;
  }

  systable_endscan(tgscan);
  table_close(tgrel, AccessShareLock);

  /* There might not be any triggers */
  if (numtrigs == 0)
  {
    pfree(triggers);
    return;
  }

  /* Build trigdesc */
  trigdesc = palloc0_object(TriggerDesc);
  trigdesc->triggers = triggers;
  trigdesc->numtriggers = numtrigs;
  for (i = 0; i < numtrigs; i++)
    SetTriggerFlags(trigdesc, &(triggers[i]));

  /* Copy completed trigdesc into cache storage */
  oldContext = MemoryContextSwitchTo(CacheMemoryContext);
  relation->trigdesc = CopyTriggerDesc(trigdesc);
  MemoryContextSwitchTo(oldContext);

  /* Release working memory */
  FreeTriggerDesc(trigdesc);
}

/*
 * Update the TriggerDesc's hint flags to include the specified trigger
 */
static void
SetTriggerFlags(TriggerDesc *trigdesc, Trigger *trigger)
{
  int16   tgtype = trigger->tgtype;

  trigdesc->trig_insert_before_row |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
               TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_INSERT);
  trigdesc->trig_insert_after_row |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
               TRIGGER_TYPE_AFTER, TRIGGER_TYPE_INSERT);
  trigdesc->trig_insert_instead_row |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
               TRIGGER_TYPE_INSTEAD, TRIGGER_TYPE_INSERT);
  trigdesc->trig_insert_before_statement |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
               TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_INSERT);
  trigdesc->trig_insert_after_statement |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
               TRIGGER_TYPE_AFTER, TRIGGER_TYPE_INSERT);
  trigdesc->trig_update_before_row |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
               TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_UPDATE);
  trigdesc->trig_update_after_row |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
               TRIGGER_TYPE_AFTER, TRIGGER_TYPE_UPDATE);
  trigdesc->trig_update_instead_row |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
               TRIGGER_TYPE_INSTEAD, TRIGGER_TYPE_UPDATE);
  trigdesc->trig_update_before_statement |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
               TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_UPDATE);
  trigdesc->trig_update_after_statement |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
               TRIGGER_TYPE_AFTER, TRIGGER_TYPE_UPDATE);
  trigdesc->trig_delete_before_row |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
               TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_DELETE);
  trigdesc->trig_delete_after_row |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
               TRIGGER_TYPE_AFTER, TRIGGER_TYPE_DELETE);
  trigdesc->trig_delete_instead_row |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_ROW,
               TRIGGER_TYPE_INSTEAD, TRIGGER_TYPE_DELETE);
  trigdesc->trig_delete_before_statement |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
               TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_DELETE);
  trigdesc->trig_delete_after_statement |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
               TRIGGER_TYPE_AFTER, TRIGGER_TYPE_DELETE);
  /* there are no row-level truncate triggers */
  trigdesc->trig_truncate_before_statement |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
               TRIGGER_TYPE_BEFORE, TRIGGER_TYPE_TRUNCATE);
  trigdesc->trig_truncate_after_statement |=
    TRIGGER_TYPE_MATCHES(tgtype, TRIGGER_TYPE_STATEMENT,
               TRIGGER_TYPE_AFTER, TRIGGER_TYPE_TRUNCATE);

  trigdesc->trig_insert_new_table |=
    (TRIGGER_FOR_INSERT(tgtype) &&
     TRIGGER_USES_TRANSITION_TABLE(trigger->tgnewtable));
  trigdesc->trig_update_old_table |=
    (TRIGGER_FOR_UPDATE(tgtype) &&
     TRIGGER_USES_TRANSITION_TABLE(trigger->tgoldtable));
  trigdesc->trig_update_new_table |=
    (TRIGGER_FOR_UPDATE(tgtype) &&
     TRIGGER_USES_TRANSITION_TABLE(trigger->tgnewtable));
  trigdesc->trig_delete_old_table |=
    (TRIGGER_FOR_DELETE(tgtype) &&
     TRIGGER_USES_TRANSITION_TABLE(trigger->tgoldtable));
}

/*
 * Copy a TriggerDesc data structure.
 *
 * The copy is allocated in the current memory context.
 */
TriggerDesc *
CopyTriggerDesc(TriggerDesc *trigdesc)
{
  TriggerDesc *newdesc;
  Trigger    *trigger;
  int     i;

  if (trigdesc == NULL || trigdesc->numtriggers <= 0)
    return NULL;

  newdesc = palloc_object(TriggerDesc);
  memcpy(newdesc, trigdesc, sizeof(TriggerDesc));

  trigger = (Trigger *) palloc(trigdesc->numtriggers * sizeof(Trigger));
  memcpy(trigger, trigdesc->triggers,
       trigdesc->numtriggers * sizeof(Trigger));
  newdesc->triggers = trigger;

  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    trigger->tgname = pstrdup(trigger->tgname);
    if (trigger->tgnattr > 0)
    {
      int16    *newattr;

      newattr = (int16 *) palloc(trigger->tgnattr * sizeof(int16));
      memcpy(newattr, trigger->tgattr,
           trigger->tgnattr * sizeof(int16));
      trigger->tgattr = newattr;
    }
    if (trigger->tgnargs > 0)
    {
      char    **newargs;
      int16   j;

      newargs = (char **) palloc(trigger->tgnargs * sizeof(char *));
      for (j = 0; j < trigger->tgnargs; j++)
        newargs[j] = pstrdup(trigger->tgargs[j]);
      trigger->tgargs = newargs;
    }
    if (trigger->tgqual)
      trigger->tgqual = pstrdup(trigger->tgqual);
    if (trigger->tgoldtable)
      trigger->tgoldtable = pstrdup(trigger->tgoldtable);
    if (trigger->tgnewtable)
      trigger->tgnewtable = pstrdup(trigger->tgnewtable);
    trigger++;
  }

  return newdesc;
}

/*
 * Free a TriggerDesc data structure.
 */
void
FreeTriggerDesc(TriggerDesc *trigdesc)
{
  Trigger    *trigger;
  int     i;

  if (trigdesc == NULL)
    return;

  trigger = trigdesc->triggers;
  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    pfree(trigger->tgname);
    if (trigger->tgnattr > 0)
      pfree(trigger->tgattr);
    if (trigger->tgnargs > 0)
    {
      while (--(trigger->tgnargs) >= 0)
        pfree(trigger->tgargs[trigger->tgnargs]);
      pfree(trigger->tgargs);
    }
    if (trigger->tgqual)
      pfree(trigger->tgqual);
    if (trigger->tgoldtable)
      pfree(trigger->tgoldtable);
    if (trigger->tgnewtable)
      pfree(trigger->tgnewtable);
    trigger++;
  }
  pfree(trigdesc->triggers);
  pfree(trigdesc);
}

/*
 * Compare two TriggerDesc structures for logical equality.
 */
#ifdef NOT_USED
bool
equalTriggerDescs(TriggerDesc *trigdesc1, TriggerDesc *trigdesc2)
{
  int     i,
        j;

  /*
   * We need not examine the hint flags, just the trigger array itself; if
   * we have the same triggers with the same types, the flags should match.
   *
   * As of 7.3 we assume trigger set ordering is significant in the
   * comparison; so we just compare corresponding slots of the two sets.
   *
   * Note: comparing the stringToNode forms of the WHEN clauses means that
   * parse column locations will affect the result.  This is okay as long as
   * this function is only used for detecting exact equality, as for example
   * in checking for staleness of a cache entry.
   */
  if (trigdesc1 != NULL)
  {
    if (trigdesc2 == NULL)
      return false;
    if (trigdesc1->numtriggers != trigdesc2->numtriggers)
      return false;
    for (i = 0; i < trigdesc1->numtriggers; i++)
    {
      Trigger    *trig1 = trigdesc1->triggers + i;
      Trigger    *trig2 = trigdesc2->triggers + i;

      if (trig1->tgoid != trig2->tgoid)
        return false;
      if (strcmp(trig1->tgname, trig2->tgname) != 0)
        return false;
      if (trig1->tgfoid != trig2->tgfoid)
        return false;
      if (trig1->tgtype != trig2->tgtype)
        return false;
      if (trig1->tgenabled != trig2->tgenabled)
        return false;
      if (trig1->tgisinternal != trig2->tgisinternal)
        return false;
      if (trig1->tgisclone != trig2->tgisclone)
        return false;
      if (trig1->tgconstrrelid != trig2->tgconstrrelid)
        return false;
      if (trig1->tgconstrindid != trig2->tgconstrindid)
        return false;
      if (trig1->tgconstraint != trig2->tgconstraint)
        return false;
      if (trig1->tgdeferrable != trig2->tgdeferrable)
        return false;
      if (trig1->tginitdeferred != trig2->tginitdeferred)
        return false;
      if (trig1->tgnargs != trig2->tgnargs)
        return false;
      if (trig1->tgnattr != trig2->tgnattr)
        return false;
      if (trig1->tgnattr > 0 &&
        memcmp(trig1->tgattr, trig2->tgattr,
             trig1->tgnattr * sizeof(int16)) != 0)
        return false;
      for (j = 0; j < trig1->tgnargs; j++)
        if (strcmp(trig1->tgargs[j], trig2->tgargs[j]) != 0)
          return false;
      if (trig1->tgqual == NULL && trig2->tgqual == NULL)
         /* ok */ ;
      else if (trig1->tgqual == NULL || trig2->tgqual == NULL)
        return false;
      else if (strcmp(trig1->tgqual, trig2->tgqual) != 0)
        return false;
      if (trig1->tgoldtable == NULL && trig2->tgoldtable == NULL)
         /* ok */ ;
      else if (trig1->tgoldtable == NULL || trig2->tgoldtable == NULL)
        return false;
      else if (strcmp(trig1->tgoldtable, trig2->tgoldtable) != 0)
        return false;
      if (trig1->tgnewtable == NULL && trig2->tgnewtable == NULL)
         /* ok */ ;
      else if (trig1->tgnewtable == NULL || trig2->tgnewtable == NULL)
        return false;
      else if (strcmp(trig1->tgnewtable, trig2->tgnewtable) != 0)
        return false;
    }
  }
  else if (trigdesc2 != NULL)
    return false;
  return true;
}
#endif              /* NOT_USED */

/*
 * Check if there is a row-level trigger with transition tables that prevents
 * a table from becoming an inheritance child or partition.  Return the name
 * of the first such incompatible trigger, or NULL if there is none.
 */
const char *
FindTriggerIncompatibleWithInheritance(TriggerDesc *trigdesc)
{
  if (trigdesc != NULL)
  {
    int     i;

    for (i = 0; i < trigdesc->numtriggers; ++i)
    {
      Trigger    *trigger = &trigdesc->triggers[i];

      if (!TRIGGER_FOR_ROW(trigger->tgtype))
        continue;
      if (trigger->tgoldtable != NULL || trigger->tgnewtable != NULL)
        return trigger->tgname;
    }
  }

  return NULL;
}

/*
 * Call a trigger function.
 *
 *    trigdata: trigger descriptor.
 *    tgindx: trigger's index in finfo and instr arrays.
 *    finfo: array of cached trigger function call information.
 *    instr: optional array of EXPLAIN ANALYZE instrumentation state.
 *    per_tuple_context: memory context to execute the function in.
 *
 * Returns the tuple (or NULL) as returned by the function.
 */
static HeapTuple
ExecCallTriggerFunc(TriggerData *trigdata,
          int tgindx,
          FmgrInfo *finfo,
          TriggerInstrumentation *instr,
          MemoryContext per_tuple_context)
{
  LOCAL_FCINFO(fcinfo, 0);
  PgStat_FunctionCallUsage fcusage;
  Datum   result;
  MemoryContext oldContext;

  /*
   * Protect against code paths that may fail to initialize transition table
   * info.
   */
  Assert(((TRIGGER_FIRED_BY_INSERT(trigdata->tg_event) ||
       TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event) ||
       TRIGGER_FIRED_BY_DELETE(trigdata->tg_event)) &&
      TRIGGER_FIRED_AFTER(trigdata->tg_event) &&
      !(trigdata->tg_event & AFTER_TRIGGER_DEFERRABLE) &&
      !(trigdata->tg_event & AFTER_TRIGGER_INITDEFERRED)) ||
       (trigdata->tg_oldtable == NULL && trigdata->tg_newtable == NULL));

  finfo += tgindx;

  /*
   * We cache fmgr lookup info, to avoid making the lookup again on each
   * call.
   */
  if (finfo->fn_oid == InvalidOid)
    fmgr_info(trigdata->tg_trigger->tgfoid, finfo);

  Assert(finfo->fn_oid == trigdata->tg_trigger->tgfoid);

  /*
   * If doing EXPLAIN ANALYZE, start charging time to this trigger.
   */
  if (instr)
    InstrStartTrigger(instr + tgindx);

  /*
   * Do the function evaluation in the per-tuple memory context, so that
   * leaked memory will be reclaimed once per tuple. Note in particular that
   * any new tuple created by the trigger function will live till the end of
   * the tuple cycle.
   */
  oldContext = MemoryContextSwitchTo(per_tuple_context);

  /*
   * Call the function, passing no arguments but setting a context.
   */
  InitFunctionCallInfoData(*fcinfo, finfo, 0,
               InvalidOid, (Node *) trigdata, NULL);

  pgstat_init_function_usage(fcinfo, &fcusage);

  MyTriggerDepth++;
  PG_TRY();
  {
    result = FunctionCallInvoke(fcinfo);
  }
  PG_FINALLY();
  {
    MyTriggerDepth--;
  }
  PG_END_TRY();

  pgstat_end_function_usage(&fcusage, true);

  MemoryContextSwitchTo(oldContext);

  /*
   * Trigger protocol allows function to return a null pointer, but NOT to
   * set the isnull result flag.
   */
  if (fcinfo->isnull)
    ereport(ERROR,
        (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
         errmsg("trigger function %u returned null value",
            fcinfo->flinfo->fn_oid)));

  /*
   * If doing EXPLAIN ANALYZE, stop charging time to this trigger, and count
   * the firing of the trigger.
   */
  if (instr)
    InstrStopTrigger(instr + tgindx, 1);

  return (HeapTuple) DatumGetPointer(result);
}

void
ExecBSInsertTriggers(EState *estate, ResultRelInfo *relinfo)
{
  TriggerDesc *trigdesc;
  int     i;
  TriggerData LocTriggerData = {0};

  trigdesc = relinfo->ri_TrigDesc;

  if (trigdesc == NULL)
    return;
  if (!trigdesc->trig_insert_before_statement)
    return;

  /* no-op if we already fired BS triggers in this context */
  if (before_stmt_triggers_fired(RelationGetRelid(relinfo->ri_RelationDesc),
                   CMD_INSERT))
    return;

  LocTriggerData.type = T_TriggerData;
  LocTriggerData.tg_event = TRIGGER_EVENT_INSERT |
    TRIGGER_EVENT_BEFORE;
  LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    Trigger    *trigger = &trigdesc->triggers[i];
    HeapTuple newtuple;

    if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
                  TRIGGER_TYPE_STATEMENT,
                  TRIGGER_TYPE_BEFORE,
                  TRIGGER_TYPE_INSERT))
      continue;
    if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
              NULL, NULL, NULL))
      continue;

    LocTriggerData.tg_trigger = trigger;
    newtuple = ExecCallTriggerFunc(&LocTriggerData,
                     i,
                     relinfo->ri_TrigFunctions,
                     relinfo->ri_TrigInstrument,
                     GetPerTupleMemoryContext(estate));

    if (newtuple)
      ereport(ERROR,
          (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
           errmsg("BEFORE STATEMENT trigger cannot return a value")));
  }
}

void
ExecASInsertTriggers(EState *estate, ResultRelInfo *relinfo,
           TransitionCaptureState *transition_capture)
{
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;

  if (trigdesc && trigdesc->trig_insert_after_statement)
    AfterTriggerSaveEvent(estate, relinfo, NULL, NULL,
                TRIGGER_EVENT_INSERT,
                false, NULL, NULL, NIL, NULL, transition_capture,
                false);
}

bool
ExecBRInsertTriggers(EState *estate, ResultRelInfo *relinfo,
           TupleTableSlot *slot)
{
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  HeapTuple newtuple = NULL;
  bool    should_free;
  TriggerData LocTriggerData = {0};
  int     i;

  LocTriggerData.type = T_TriggerData;
  LocTriggerData.tg_event = TRIGGER_EVENT_INSERT |
    TRIGGER_EVENT_ROW |
    TRIGGER_EVENT_BEFORE;
  LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    Trigger    *trigger = &trigdesc->triggers[i];
    HeapTuple oldtuple;

    if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
                  TRIGGER_TYPE_ROW,
                  TRIGGER_TYPE_BEFORE,
                  TRIGGER_TYPE_INSERT))
      continue;
    if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
              NULL, NULL, slot))
      continue;

    if (!newtuple)
      newtuple = ExecFetchSlotHeapTuple(slot, true, &should_free);

    LocTriggerData.tg_trigslot = slot;
    LocTriggerData.tg_trigtuple = oldtuple = newtuple;
    LocTriggerData.tg_trigger = trigger;
    newtuple = ExecCallTriggerFunc(&LocTriggerData,
                     i,
                     relinfo->ri_TrigFunctions,
                     relinfo->ri_TrigInstrument,
                     GetPerTupleMemoryContext(estate));
    if (newtuple == NULL)
    {
      if (should_free)
        heap_freetuple(oldtuple);
      return false;    /* "do nothing" */
    }
    else if (newtuple != oldtuple)
    {
      newtuple = check_modified_virtual_generated(RelationGetDescr(relinfo->ri_RelationDesc), newtuple);

      ExecForceStoreHeapTuple(newtuple, slot, false);

      /*
       * After a tuple in a partition goes through a trigger, the user
       * could have changed the partition key enough that the tuple no
       * longer fits the partition.  Verify that.
       */
      if (trigger->tgisclone &&
        !ExecPartitionCheck(relinfo, slot, estate, false))
        ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("moving row to another partition during a BEFORE FOR EACH ROW trigger is not supported"),
             errdetail("Before executing trigger \"%s\", the row was to be in partition \"%s.%s\".",
                   trigger->tgname,
                   get_namespace_name(RelationGetNamespace(relinfo->ri_RelationDesc)),
                   RelationGetRelationName(relinfo->ri_RelationDesc))));

      if (should_free)
        heap_freetuple(oldtuple);

      /* signal tuple should be re-fetched if used */
      newtuple = NULL;
    }
  }

  return true;
}

void
ExecARInsertTriggers(EState *estate, ResultRelInfo *relinfo,
           TupleTableSlot *slot, List *recheckIndexes,
           TransitionCaptureState *transition_capture)
{
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;

  if (relinfo->ri_FdwRoutine && transition_capture &&
    transition_capture->tcs_insert_new_table)
  {
    Assert(relinfo->ri_RootResultRelInfo);
    ereport(ERROR,
        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
         errmsg("cannot collect transition tuples from child foreign tables")));
  }

  if ((trigdesc && trigdesc->trig_insert_after_row) ||
    (transition_capture && transition_capture->tcs_insert_new_table))
    AfterTriggerSaveEvent(estate, relinfo, NULL, NULL,
                TRIGGER_EVENT_INSERT,
                true, NULL, slot,
                recheckIndexes, NULL,
                transition_capture,
                false);
}

bool
ExecIRInsertTriggers(EState *estate, ResultRelInfo *relinfo,
           TupleTableSlot *slot)
{
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  HeapTuple newtuple = NULL;
  bool    should_free;
  TriggerData LocTriggerData = {0};
  int     i;

  LocTriggerData.type = T_TriggerData;
  LocTriggerData.tg_event = TRIGGER_EVENT_INSERT |
    TRIGGER_EVENT_ROW |
    TRIGGER_EVENT_INSTEAD;
  LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    Trigger    *trigger = &trigdesc->triggers[i];
    HeapTuple oldtuple;

    if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
                  TRIGGER_TYPE_ROW,
                  TRIGGER_TYPE_INSTEAD,
                  TRIGGER_TYPE_INSERT))
      continue;
    if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
              NULL, NULL, slot))
      continue;

    if (!newtuple)
      newtuple = ExecFetchSlotHeapTuple(slot, true, &should_free);

    LocTriggerData.tg_trigslot = slot;
    LocTriggerData.tg_trigtuple = oldtuple = newtuple;
    LocTriggerData.tg_trigger = trigger;
    newtuple = ExecCallTriggerFunc(&LocTriggerData,
                     i,
                     relinfo->ri_TrigFunctions,
                     relinfo->ri_TrigInstrument,
                     GetPerTupleMemoryContext(estate));
    if (newtuple == NULL)
    {
      if (should_free)
        heap_freetuple(oldtuple);
      return false;    /* "do nothing" */
    }
    else if (newtuple != oldtuple)
    {
      ExecForceStoreHeapTuple(newtuple, slot, false);

      if (should_free)
        heap_freetuple(oldtuple);

      /* signal tuple should be re-fetched if used */
      newtuple = NULL;
    }
  }

  return true;
}

void
ExecBSDeleteTriggers(EState *estate, ResultRelInfo *relinfo)
{
  TriggerDesc *trigdesc;
  int     i;
  TriggerData LocTriggerData = {0};

  trigdesc = relinfo->ri_TrigDesc;

  if (trigdesc == NULL)
    return;
  if (!trigdesc->trig_delete_before_statement)
    return;

  /* no-op if we already fired BS triggers in this context */
  if (before_stmt_triggers_fired(RelationGetRelid(relinfo->ri_RelationDesc),
                   CMD_DELETE))
    return;

  LocTriggerData.type = T_TriggerData;
  LocTriggerData.tg_event = TRIGGER_EVENT_DELETE |
    TRIGGER_EVENT_BEFORE;
  LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    Trigger    *trigger = &trigdesc->triggers[i];
    HeapTuple newtuple;

    if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
                  TRIGGER_TYPE_STATEMENT,
                  TRIGGER_TYPE_BEFORE,
                  TRIGGER_TYPE_DELETE))
      continue;
    if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
              NULL, NULL, NULL))
      continue;

    LocTriggerData.tg_trigger = trigger;
    newtuple = ExecCallTriggerFunc(&LocTriggerData,
                     i,
                     relinfo->ri_TrigFunctions,
                     relinfo->ri_TrigInstrument,
                     GetPerTupleMemoryContext(estate));

    if (newtuple)
      ereport(ERROR,
          (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
           errmsg("BEFORE STATEMENT trigger cannot return a value")));
  }
}

void
ExecASDeleteTriggers(EState *estate, ResultRelInfo *relinfo,
           TransitionCaptureState *transition_capture)
{
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;

  if (trigdesc && trigdesc->trig_delete_after_statement)
    AfterTriggerSaveEvent(estate, relinfo, NULL, NULL,
                TRIGGER_EVENT_DELETE,
                false, NULL, NULL, NIL, NULL, transition_capture,
                false);
}

/*
 * Execute BEFORE ROW DELETE triggers.
 *
 * True indicates caller can proceed with the delete.  False indicates caller
 * need to suppress the delete and additionally if requested, we need to pass
 * back the concurrently updated tuple if any.
 */
bool
ExecBRDeleteTriggers(EState *estate, EPQState *epqstate,
           ResultRelInfo *relinfo,
           ItemPointer tupleid,
           HeapTuple fdw_trigtuple,
           TupleTableSlot **epqslot,
           TM_Result *tmresult,
           TM_FailureData *tmfd,
           bool is_merge_delete)
{
  TupleTableSlot *slot = ExecGetTriggerOldSlot(estate, relinfo);
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  bool    result = true;
  TriggerData LocTriggerData = {0};
  HeapTuple trigtuple;
  bool    should_free = false;
  int     i;

  Assert(HeapTupleIsValid(fdw_trigtuple) ^ ItemPointerIsValid(tupleid));
  if (fdw_trigtuple == NULL)
  {
    TupleTableSlot *epqslot_candidate = NULL;

    /*
     * Get a copy of the on-disk tuple we are planning to delete.  In
     * general, if the tuple has been concurrently updated, we should
     * recheck it using EPQ.  However, if this is a MERGE DELETE action,
     * we skip this EPQ recheck and leave it to the caller (it must do
     * additional rechecking, and might end up executing a different
     * action entirely).
     */
    if (!GetTupleForTrigger(estate, epqstate, relinfo, tupleid,
                LockTupleExclusive, slot, !is_merge_delete,
                &epqslot_candidate, tmresult, tmfd))
      return false;

    /*
     * If the tuple was concurrently updated and the caller of this
     * function requested for the updated tuple, skip the trigger
     * execution.
     */
    if (epqslot_candidate != NULL && epqslot != NULL)
    {
      *epqslot = epqslot_candidate;
      return false;
    }

    trigtuple = ExecFetchSlotHeapTuple(slot, true, &should_free);
  }
  else
  {
    trigtuple = fdw_trigtuple;
    ExecForceStoreHeapTuple(trigtuple, slot, false);
  }

  LocTriggerData.type = T_TriggerData;
  LocTriggerData.tg_event = TRIGGER_EVENT_DELETE |
    TRIGGER_EVENT_ROW |
    TRIGGER_EVENT_BEFORE;
  LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    HeapTuple newtuple;
    Trigger    *trigger = &trigdesc->triggers[i];

    if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
                  TRIGGER_TYPE_ROW,
                  TRIGGER_TYPE_BEFORE,
                  TRIGGER_TYPE_DELETE))
      continue;
    if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
              NULL, slot, NULL))
      continue;

    LocTriggerData.tg_trigslot = slot;
    LocTriggerData.tg_trigtuple = trigtuple;
    LocTriggerData.tg_trigger = trigger;
    newtuple = ExecCallTriggerFunc(&LocTriggerData,
                     i,
                     relinfo->ri_TrigFunctions,
                     relinfo->ri_TrigInstrument,
                     GetPerTupleMemoryContext(estate));
    if (newtuple == NULL)
    {
      result = false;    /* tell caller to suppress delete */
      break;
    }
    if (newtuple != trigtuple)
      heap_freetuple(newtuple);
  }
  if (should_free)
    heap_freetuple(trigtuple);

  return result;
}

/*
 * Note: is_crosspart_update must be true if the DELETE is being performed
 * as part of a cross-partition update.
 */
void
ExecARDeleteTriggers(EState *estate,
           ResultRelInfo *relinfo,
           ItemPointer tupleid,
           HeapTuple fdw_trigtuple,
           TransitionCaptureState *transition_capture,
           bool is_crosspart_update)
{
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;

  if (relinfo->ri_FdwRoutine && transition_capture &&
    transition_capture->tcs_delete_old_table)
  {
    Assert(relinfo->ri_RootResultRelInfo);
    ereport(ERROR,
        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
         errmsg("cannot collect transition tuples from child foreign tables")));
  }

  if ((trigdesc && trigdesc->trig_delete_after_row) ||
    (transition_capture && transition_capture->tcs_delete_old_table))
  {
    TupleTableSlot *slot = ExecGetTriggerOldSlot(estate, relinfo);

    Assert(HeapTupleIsValid(fdw_trigtuple) ^ ItemPointerIsValid(tupleid));
    if (fdw_trigtuple == NULL)
      GetTupleForTrigger(estate,
                 NULL,
                 relinfo,
                 tupleid,
                 LockTupleExclusive,
                 slot,
                 false,
                 NULL,
                 NULL,
                 NULL);
    else
      ExecForceStoreHeapTuple(fdw_trigtuple, slot, false);

    AfterTriggerSaveEvent(estate, relinfo, NULL, NULL,
                TRIGGER_EVENT_DELETE,
                true, slot, NULL, NIL, NULL,
                transition_capture,
                is_crosspart_update);
  }
}

bool
ExecIRDeleteTriggers(EState *estate, ResultRelInfo *relinfo,
           HeapTuple trigtuple)
{
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  TupleTableSlot *slot = ExecGetTriggerOldSlot(estate, relinfo);
  TriggerData LocTriggerData = {0};
  int     i;

  LocTriggerData.type = T_TriggerData;
  LocTriggerData.tg_event = TRIGGER_EVENT_DELETE |
    TRIGGER_EVENT_ROW |
    TRIGGER_EVENT_INSTEAD;
  LocTriggerData.tg_relation = relinfo->ri_RelationDesc;

  ExecForceStoreHeapTuple(trigtuple, slot, false);

  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    HeapTuple rettuple;
    Trigger    *trigger = &trigdesc->triggers[i];

    if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
                  TRIGGER_TYPE_ROW,
                  TRIGGER_TYPE_INSTEAD,
                  TRIGGER_TYPE_DELETE))
      continue;
    if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
              NULL, slot, NULL))
      continue;

    LocTriggerData.tg_trigslot = slot;
    LocTriggerData.tg_trigtuple = trigtuple;
    LocTriggerData.tg_trigger = trigger;
    rettuple = ExecCallTriggerFunc(&LocTriggerData,
                     i,
                     relinfo->ri_TrigFunctions,
                     relinfo->ri_TrigInstrument,
                     GetPerTupleMemoryContext(estate));
    if (rettuple == NULL)
      return false;   /* Delete was suppressed */
    if (rettuple != trigtuple)
      heap_freetuple(rettuple);
  }
  return true;
}

void
ExecBSUpdateTriggers(EState *estate, ResultRelInfo *relinfo)
{
  TriggerDesc *trigdesc;
  int     i;
  TriggerData LocTriggerData = {0};
  Bitmapset  *updatedCols;

  trigdesc = relinfo->ri_TrigDesc;

  if (trigdesc == NULL)
    return;
  if (!trigdesc->trig_update_before_statement)
    return;

  /* no-op if we already fired BS triggers in this context */
  if (before_stmt_triggers_fired(RelationGetRelid(relinfo->ri_RelationDesc),
                   CMD_UPDATE))
    return;

  /* statement-level triggers operate on the parent table */
  Assert(relinfo->ri_RootResultRelInfo == NULL);

  updatedCols = ExecGetAllUpdatedCols(relinfo, estate);

  LocTriggerData.type = T_TriggerData;
  LocTriggerData.tg_event = TRIGGER_EVENT_UPDATE |
    TRIGGER_EVENT_BEFORE;
  LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  LocTriggerData.tg_updatedcols = updatedCols;
  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    Trigger    *trigger = &trigdesc->triggers[i];
    HeapTuple newtuple;

    if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
                  TRIGGER_TYPE_STATEMENT,
                  TRIGGER_TYPE_BEFORE,
                  TRIGGER_TYPE_UPDATE))
      continue;
    if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
              updatedCols, NULL, NULL))
      continue;

    LocTriggerData.tg_trigger = trigger;
    newtuple = ExecCallTriggerFunc(&LocTriggerData,
                     i,
                     relinfo->ri_TrigFunctions,
                     relinfo->ri_TrigInstrument,
                     GetPerTupleMemoryContext(estate));

    if (newtuple)
      ereport(ERROR,
          (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
           errmsg("BEFORE STATEMENT trigger cannot return a value")));
  }
}

void
ExecASUpdateTriggers(EState *estate, ResultRelInfo *relinfo,
           TransitionCaptureState *transition_capture)
{
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;

  /* statement-level triggers operate on the parent table */
  Assert(relinfo->ri_RootResultRelInfo == NULL);

  if (trigdesc && trigdesc->trig_update_after_statement)
    AfterTriggerSaveEvent(estate, relinfo, NULL, NULL,
                TRIGGER_EVENT_UPDATE,
                false, NULL, NULL, NIL,
                ExecGetAllUpdatedCols(relinfo, estate),
                transition_capture,
                false);
}

bool
ExecBRUpdateTriggers(EState *estate, EPQState *epqstate,
           ResultRelInfo *relinfo,
           ItemPointer tupleid,
           HeapTuple fdw_trigtuple,
           TupleTableSlot *newslot,
           TM_Result *tmresult,
           TM_FailureData *tmfd,
           bool is_merge_update)
{
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  TupleTableSlot *oldslot = ExecGetTriggerOldSlot(estate, relinfo);
  HeapTuple newtuple = NULL;
  HeapTuple trigtuple;
  bool    should_free_trig = false;
  bool    should_free_new = false;
  TriggerData LocTriggerData = {0};
  int     i;
  Bitmapset  *updatedCols;
  LockTupleMode lockmode;

  /* Determine lock mode to use */
  lockmode = ExecUpdateLockMode(estate, relinfo);

  Assert(HeapTupleIsValid(fdw_trigtuple) ^ ItemPointerIsValid(tupleid));
  if (fdw_trigtuple == NULL)
  {
    TupleTableSlot *epqslot_candidate = NULL;

    /*
     * Get a copy of the on-disk tuple we are planning to update.  In
     * general, if the tuple has been concurrently updated, we should
     * recheck it using EPQ.  However, if this is a MERGE UPDATE action,
     * we skip this EPQ recheck and leave it to the caller (it must do
     * additional rechecking, and might end up executing a different
     * action entirely).
     */
    if (!GetTupleForTrigger(estate, epqstate, relinfo, tupleid,
                lockmode, oldslot, !is_merge_update,
                &epqslot_candidate, tmresult, tmfd))
      return false;   /* cancel the update action */

    /*
     * In READ COMMITTED isolation level it's possible that target tuple
     * was changed due to concurrent update.  In that case we have a raw
     * subplan output tuple in epqslot_candidate, and need to form a new
     * insertable tuple using ExecGetUpdateNewTuple to replace the one we
     * received in newslot.  Neither we nor our callers have any further
     * interest in the passed-in tuple, so it's okay to overwrite newslot
     * with the newer data.
     */
    if (epqslot_candidate != NULL)
    {
      TupleTableSlot *epqslot_clean;

      epqslot_clean = ExecGetUpdateNewTuple(relinfo, epqslot_candidate,
                          oldslot);

      /*
       * Typically, the caller's newslot was also generated by
       * ExecGetUpdateNewTuple, so that epqslot_clean will be the same
       * slot and copying is not needed.  But do the right thing if it
       * isn't.
       */
      if (unlikely(newslot != epqslot_clean))
        ExecCopySlot(newslot, epqslot_clean);

      /*
       * At this point newslot contains a virtual tuple that may
       * reference some fields of oldslot's tuple in some disk buffer.
       * If that tuple is in a different page than the original target
       * tuple, then our only pin on that buffer is oldslot's, and we're
       * about to release it.  Hence we'd better materialize newslot to
       * ensure it doesn't contain references into an unpinned buffer.
       * (We'd materialize it below anyway, but too late for safety.)
       */
      ExecMaterializeSlot(newslot);
    }

    /*
     * Here we convert oldslot to a materialized slot holding trigtuple.
     * Neither slot passed to the triggers will hold any buffer pin.
     */
    trigtuple = ExecFetchSlotHeapTuple(oldslot, true, &should_free_trig);
  }
  else
  {
    /* Put the FDW-supplied tuple into oldslot to unify the cases */
    ExecForceStoreHeapTuple(fdw_trigtuple, oldslot, false);
    trigtuple = fdw_trigtuple;
  }

  LocTriggerData.type = T_TriggerData;
  LocTriggerData.tg_event = TRIGGER_EVENT_UPDATE |
    TRIGGER_EVENT_ROW |
    TRIGGER_EVENT_BEFORE;
  LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
  updatedCols = ExecGetAllUpdatedCols(relinfo, estate);
  LocTriggerData.tg_updatedcols = updatedCols;
  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    Trigger    *trigger = &trigdesc->triggers[i];
    HeapTuple oldtuple;

    if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
                  TRIGGER_TYPE_ROW,
                  TRIGGER_TYPE_BEFORE,
                  TRIGGER_TYPE_UPDATE))
      continue;
    if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
              updatedCols, oldslot, newslot))
      continue;

    if (!newtuple)
      newtuple = ExecFetchSlotHeapTuple(newslot, true, &should_free_new);

    LocTriggerData.tg_trigslot = oldslot;
    LocTriggerData.tg_trigtuple = trigtuple;
    LocTriggerData.tg_newtuple = oldtuple = newtuple;
    LocTriggerData.tg_newslot = newslot;
    LocTriggerData.tg_trigger = trigger;
    newtuple = ExecCallTriggerFunc(&LocTriggerData,
                     i,
                     relinfo->ri_TrigFunctions,
                     relinfo->ri_TrigInstrument,
                     GetPerTupleMemoryContext(estate));

    if (newtuple == NULL)
    {
      if (should_free_trig)
        heap_freetuple(trigtuple);
      if (should_free_new)
        heap_freetuple(oldtuple);
      return false;    /* "do nothing" */
    }
    else if (newtuple != oldtuple)
    {
      newtuple = check_modified_virtual_generated(RelationGetDescr(relinfo->ri_RelationDesc), newtuple);

      ExecForceStoreHeapTuple(newtuple, newslot, false);

      /*
       * If the tuple returned by the trigger / being stored, is the old
       * row version, and the heap tuple passed to the trigger was
       * allocated locally, materialize the slot. Otherwise we might
       * free it while still referenced by the slot.
       */
      if (should_free_trig && newtuple == trigtuple)
        ExecMaterializeSlot(newslot);

      if (should_free_new)
        heap_freetuple(oldtuple);

      /* signal tuple should be re-fetched if used */
      newtuple = NULL;
    }
  }
  if (should_free_trig)
    heap_freetuple(trigtuple);

  return true;
}

/*
 * Note: 'src_partinfo' and 'dst_partinfo', when non-NULL, refer to the source
 * and destination partitions, respectively, of a cross-partition update of
 * the root partitioned table mentioned in the query, given by 'relinfo'.
 * 'tupleid' in that case refers to the ctid of the "old" tuple in the source
 * partition, and 'newslot' contains the "new" tuple in the destination
 * partition.  This interface allows to support the requirements of
 * ExecCrossPartitionUpdateForeignKey(); is_crosspart_update must be true in
 * that case.
 */
void
ExecARUpdateTriggers(EState *estate, ResultRelInfo *relinfo,
           ResultRelInfo *src_partinfo,
           ResultRelInfo *dst_partinfo,
           ItemPointer tupleid,
           HeapTuple fdw_trigtuple,
           TupleTableSlot *newslot,
           List *recheckIndexes,
           TransitionCaptureState *transition_capture,
           bool is_crosspart_update)
{
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;

  if (relinfo->ri_FdwRoutine && transition_capture &&
    (transition_capture->tcs_update_old_table ||
     transition_capture->tcs_update_new_table))
  {
    Assert(relinfo->ri_RootResultRelInfo);
    ereport(ERROR,
        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
         errmsg("cannot collect transition tuples from child foreign tables")));
  }

  if ((trigdesc && trigdesc->trig_update_after_row) ||
    (transition_capture &&
     (transition_capture->tcs_update_old_table ||
      transition_capture->tcs_update_new_table)))
  {
    /*
     * Note: if the UPDATE is converted into a DELETE+INSERT as part of
     * update-partition-key operation, then this function is also called
     * separately for DELETE and INSERT to capture transition table rows.
     * In such case, either old tuple or new tuple can be NULL.
     */
    TupleTableSlot *oldslot;
    ResultRelInfo *tupsrc;

    Assert((src_partinfo != NULL && dst_partinfo != NULL) ||
         !is_crosspart_update);

    tupsrc = src_partinfo ? src_partinfo : relinfo;
    oldslot = ExecGetTriggerOldSlot(estate, tupsrc);

    if (fdw_trigtuple == NULL && ItemPointerIsValid(tupleid))
      GetTupleForTrigger(estate,
                 NULL,
                 tupsrc,
                 tupleid,
                 LockTupleExclusive,
                 oldslot,
                 false,
                 NULL,
                 NULL,
                 NULL);
    else if (fdw_trigtuple != NULL)
      ExecForceStoreHeapTuple(fdw_trigtuple, oldslot, false);
    else
      ExecClearTuple(oldslot);

    AfterTriggerSaveEvent(estate, relinfo,
                src_partinfo, dst_partinfo,
                TRIGGER_EVENT_UPDATE,
                true,
                oldslot, newslot, recheckIndexes,
                ExecGetAllUpdatedCols(relinfo, estate),
                transition_capture,
                is_crosspart_update);
  }
}

bool
ExecIRUpdateTriggers(EState *estate, ResultRelInfo *relinfo,
           HeapTuple trigtuple, TupleTableSlot *newslot)
{
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  TupleTableSlot *oldslot = ExecGetTriggerOldSlot(estate, relinfo);
  HeapTuple newtuple = NULL;
  bool    should_free;
  TriggerData LocTriggerData = {0};
  int     i;

  LocTriggerData.type = T_TriggerData;
  LocTriggerData.tg_event = TRIGGER_EVENT_UPDATE |
    TRIGGER_EVENT_ROW |
    TRIGGER_EVENT_INSTEAD;
  LocTriggerData.tg_relation = relinfo->ri_RelationDesc;

  ExecForceStoreHeapTuple(trigtuple, oldslot, false);

  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    Trigger    *trigger = &trigdesc->triggers[i];
    HeapTuple oldtuple;

    if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
                  TRIGGER_TYPE_ROW,
                  TRIGGER_TYPE_INSTEAD,
                  TRIGGER_TYPE_UPDATE))
      continue;
    if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
              NULL, oldslot, newslot))
      continue;

    if (!newtuple)
      newtuple = ExecFetchSlotHeapTuple(newslot, true, &should_free);

    LocTriggerData.tg_trigslot = oldslot;
    LocTriggerData.tg_trigtuple = trigtuple;
    LocTriggerData.tg_newslot = newslot;
    LocTriggerData.tg_newtuple = oldtuple = newtuple;

    LocTriggerData.tg_trigger = trigger;
    newtuple = ExecCallTriggerFunc(&LocTriggerData,
                     i,
                     relinfo->ri_TrigFunctions,
                     relinfo->ri_TrigInstrument,
                     GetPerTupleMemoryContext(estate));
    if (newtuple == NULL)
    {
      return false;    /* "do nothing" */
    }
    else if (newtuple != oldtuple)
    {
      ExecForceStoreHeapTuple(newtuple, newslot, false);

      if (should_free)
        heap_freetuple(oldtuple);

      /* signal tuple should be re-fetched if used */
      newtuple = NULL;
    }
  }

  return true;
}

void
ExecBSTruncateTriggers(EState *estate, ResultRelInfo *relinfo)
{
  TriggerDesc *trigdesc;
  int     i;
  TriggerData LocTriggerData = {0};

  trigdesc = relinfo->ri_TrigDesc;

  if (trigdesc == NULL)
    return;
  if (!trigdesc->trig_truncate_before_statement)
    return;

  LocTriggerData.type = T_TriggerData;
  LocTriggerData.tg_event = TRIGGER_EVENT_TRUNCATE |
    TRIGGER_EVENT_BEFORE;
  LocTriggerData.tg_relation = relinfo->ri_RelationDesc;

  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    Trigger    *trigger = &trigdesc->triggers[i];
    HeapTuple newtuple;

    if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
                  TRIGGER_TYPE_STATEMENT,
                  TRIGGER_TYPE_BEFORE,
                  TRIGGER_TYPE_TRUNCATE))
      continue;
    if (!TriggerEnabled(estate, relinfo, trigger, LocTriggerData.tg_event,
              NULL, NULL, NULL))
      continue;

    LocTriggerData.tg_trigger = trigger;
    newtuple = ExecCallTriggerFunc(&LocTriggerData,
                     i,
                     relinfo->ri_TrigFunctions,
                     relinfo->ri_TrigInstrument,
                     GetPerTupleMemoryContext(estate));

    if (newtuple)
      ereport(ERROR,
          (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
           errmsg("BEFORE STATEMENT trigger cannot return a value")));
  }
}

void
ExecASTruncateTriggers(EState *estate, ResultRelInfo *relinfo)
{
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;

  if (trigdesc && trigdesc->trig_truncate_after_statement)
    AfterTriggerSaveEvent(estate, relinfo,
                NULL, NULL,
                TRIGGER_EVENT_TRUNCATE,
                false, NULL, NULL, NIL, NULL, NULL,
                false);
}


/*
 * Fetch tuple into "oldslot", dealing with locking and EPQ if necessary
 */
static bool
GetTupleForTrigger(EState *estate,
           EPQState *epqstate,
           ResultRelInfo *relinfo,
           ItemPointer tid,
           LockTupleMode lockmode,
           TupleTableSlot *oldslot,
           bool do_epq_recheck,
           TupleTableSlot **epqslot,
           TM_Result *tmresultp,
           TM_FailureData *tmfdp)
{
  Relation  relation = relinfo->ri_RelationDesc;

  if (epqslot != NULL)
  {
    TM_Result test;
    TM_FailureData tmfd;
    int     lockflags = 0;

    *epqslot = NULL;

    /* caller must pass an epqstate if EvalPlanQual is possible */
    Assert(epqstate != NULL);

    /*
     * lock tuple for update
     */
    if (!IsolationUsesXactSnapshot())
      lockflags |= TUPLE_LOCK_FLAG_FIND_LAST_VERSION;
    test = table_tuple_lock(relation, tid, estate->es_snapshot, oldslot,
                estate->es_output_cid,
                lockmode, LockWaitBlock,
                lockflags,
                &tmfd);

    /* Let the caller know about the status of this operation */
    if (tmresultp)
      *tmresultp = test;
    if (tmfdp)
      *tmfdp = tmfd;

    switch (test)
    {
      case TM_SelfModified:

        /*
         * The target tuple was already updated or deleted by the
         * current command, or by a later command in the current
         * transaction.  We ignore the tuple in the former case, and
         * throw error in the latter case, for the same reasons
         * enumerated in ExecUpdate and ExecDelete in
         * nodeModifyTable.c.
         */
        if (tmfd.cmax != estate->es_output_cid)
          ereport(ERROR,
              (errcode(ERRCODE_TRIGGERED_DATA_CHANGE_VIOLATION),
               errmsg("tuple to be updated was already modified by an operation triggered by the current command"),
               errhint("Consider using an AFTER trigger instead of a BEFORE trigger to propagate changes to other rows.")));

        /* treat it as deleted; do not process */
        return false;

      case TM_Ok:
        if (tmfd.traversed)
        {
          /*
           * Recheck the tuple using EPQ, if requested.  Otherwise,
           * just return that it was concurrently updated.
           */
          if (do_epq_recheck)
          {
            *epqslot = EvalPlanQual(epqstate,
                        relation,
                        relinfo->ri_RangeTableIndex,
                        oldslot);

            /*
             * If PlanQual failed for updated tuple - we must not
             * process this tuple!
             */
            if (TupIsNull(*epqslot))
            {
              *epqslot = NULL;
              return false;
            }
          }
          else
          {
            if (tmresultp)
              *tmresultp = TM_Updated;
            return false;
          }
        }
        break;

      case TM_Updated:
        if (IsolationUsesXactSnapshot())
          ereport(ERROR,
              (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
               errmsg("could not serialize access due to concurrent update")));
        elog(ERROR, "unexpected table_tuple_lock status: %u", test);
        break;

      case TM_Deleted:
        if (IsolationUsesXactSnapshot())
          ereport(ERROR,
              (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
               errmsg("could not serialize access due to concurrent delete")));
        /* tuple was deleted */
        return false;

      case TM_Invisible:
        elog(ERROR, "attempted to lock invisible tuple");
        break;

      default:
        elog(ERROR, "unrecognized table_tuple_lock status: %u", test);
        return false; /* keep compiler quiet */
    }
  }
  else
  {
    /*
     * We expect the tuple to be present, thus very simple error handling
     * suffices.
     */
    if (!table_tuple_fetch_row_version(relation, tid, SnapshotAny,
                       oldslot))
      elog(ERROR, "failed to fetch tuple for trigger");
  }

  return true;
}

/*
 * Is trigger enabled to fire?
 */
static bool
TriggerEnabled(EState *estate, ResultRelInfo *relinfo,
         Trigger *trigger, TriggerEvent event,
         Bitmapset *modifiedCols,
         TupleTableSlot *oldslot, TupleTableSlot *newslot)
{
  /* Check replication-role-dependent enable state */
  if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA)
  {
    if (trigger->tgenabled == TRIGGER_FIRES_ON_ORIGIN ||
      trigger->tgenabled == TRIGGER_DISABLED)
      return false;
  }
  else            /* ORIGIN or LOCAL role */
  {
    if (trigger->tgenabled == TRIGGER_FIRES_ON_REPLICA ||
      trigger->tgenabled == TRIGGER_DISABLED)
      return false;
  }

  /*
   * Check for column-specific trigger (only possible for UPDATE, and in
   * fact we *must* ignore tgattr for other event types)
   */
  if (trigger->tgnattr > 0 && TRIGGER_FIRED_BY_UPDATE(event))
  {
    int     i;
    bool    modified;

    modified = false;
    for (i = 0; i < trigger->tgnattr; i++)
    {
      if (bms_is_member(trigger->tgattr[i] - FirstLowInvalidHeapAttributeNumber,
                modifiedCols))
      {
        modified = true;
        break;
      }
    }
    if (!modified)
      return false;
  }

  /* Check for WHEN clause */
  if (trigger->tgqual)
  {
    ExprState **predicate;
    ExprContext *econtext;
    MemoryContext oldContext;
    int     i;

    Assert(estate != NULL);

    /*
     * trigger is an element of relinfo->ri_TrigDesc->triggers[]; find the
     * matching element of relinfo->ri_TrigWhenExprs[]
     */
    i = trigger - relinfo->ri_TrigDesc->triggers;
    predicate = &relinfo->ri_TrigWhenExprs[i];

    /*
     * If first time through for this WHEN expression, build expression
     * nodetrees for it.  Keep them in the per-query memory context so
     * they'll survive throughout the query.
     */
    if (*predicate == NULL)
    {
      Node     *tgqual;

      oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
      tgqual = stringToNode(trigger->tgqual);
      tgqual = expand_generated_columns_in_expr(tgqual, relinfo->ri_RelationDesc, PRS2_OLD_VARNO);
      tgqual = expand_generated_columns_in_expr(tgqual, relinfo->ri_RelationDesc, PRS2_NEW_VARNO);
      /* Change references to OLD and NEW to INNER_VAR and OUTER_VAR */
      ChangeVarNodes(tgqual, PRS2_OLD_VARNO, INNER_VAR, 0);
      ChangeVarNodes(tgqual, PRS2_NEW_VARNO, OUTER_VAR, 0);
      /* ExecPrepareQual wants implicit-AND form */
      tgqual = (Node *) make_ands_implicit((Expr *) tgqual);
      *predicate = ExecPrepareQual((List *) tgqual, estate);
      MemoryContextSwitchTo(oldContext);
    }

    /*
     * We will use the EState's per-tuple context for evaluating WHEN
     * expressions (creating it if it's not already there).
     */
    econtext = GetPerTupleExprContext(estate);

    /*
     * Finally evaluate the expression, making the old and/or new tuples
     * available as INNER_VAR/OUTER_VAR respectively.
     */
    econtext->ecxt_innertuple = oldslot;
    econtext->ecxt_outertuple = newslot;
    if (!ExecQual(*predicate, econtext))
      return false;
  }

  return true;
}


/* ----------
 * After-trigger stuff
 *
 * The AfterTriggersData struct holds data about pending AFTER trigger events
 * during the current transaction tree.  (BEFORE triggers are fired
 * immediately so we don't need any persistent state about them.)  The struct
 * and most of its subsidiary data are kept in TopTransactionContext; however
 * some data that can be discarded sooner appears in the CurTransactionContext
 * of the relevant subtransaction.  Also, the individual event records are
 * kept in a separate sub-context of TopTransactionContext.  This is done
 * mainly so that it's easy to tell from a memory context dump how much space
 * is being eaten by trigger events.
 *
 * Because the list of pending events can grow large, we go to some
 * considerable effort to minimize per-event memory consumption.  The event
 * records are grouped into chunks and common data for similar events in the
 * same chunk is only stored once.
 *
 * XXX We need to be able to save the per-event data in a file if it grows too
 * large.
 * ----------
 */

/* Per-trigger SET CONSTRAINT status */
typedef struct SetConstraintTriggerData
{
  Oid     sct_tgoid;
  bool    sct_tgisdeferred;
} SetConstraintTriggerData;

typedef struct SetConstraintTriggerData *SetConstraintTrigger;

/*
 * SET CONSTRAINT intra-transaction status.
 *
 * We make this a single palloc'd object so it can be copied and freed easily.
 *
 * all_isset and all_isdeferred are used to keep track
 * of SET CONSTRAINTS ALL {DEFERRED, IMMEDIATE}.
 *
 * trigstates[] stores per-trigger tgisdeferred settings.
 */
typedef struct SetConstraintStateData
{
  bool    all_isset;
  bool    all_isdeferred;
  int     numstates;    /* number of trigstates[] entries in use */
  int     numalloc;   /* allocated size of trigstates[] */
  SetConstraintTriggerData trigstates[FLEXIBLE_ARRAY_MEMBER];
} SetConstraintStateData;

typedef SetConstraintStateData *SetConstraintState;


/*
 * Per-trigger-event data
 *
 * The actual per-event data, AfterTriggerEventData, includes DONE/IN_PROGRESS
 * status bits, up to two tuple CTIDs, and optionally two OIDs of partitions.
 * Each event record also has an associated AfterTriggerSharedData that is
 * shared across all instances of similar events within a "chunk".
 *
 * For row-level triggers, we arrange not to waste storage on unneeded ctid
 * fields.  Updates of regular tables use two; inserts and deletes of regular
 * tables use one; foreign tables always use zero and save the tuple(s) to a
 * tuplestore.  AFTER_TRIGGER_FDW_FETCH directs AfterTriggerExecute() to
 * retrieve a fresh tuple or pair of tuples from that tuplestore, while
 * AFTER_TRIGGER_FDW_REUSE directs it to use the most-recently-retrieved
 * tuple(s).  This permits storing tuples once regardless of the number of
 * row-level triggers on a foreign table.
 *
 * When updates on partitioned tables cause rows to move between partitions,
 * the OIDs of both partitions are stored too, so that the tuples can be
 * fetched; such entries are marked AFTER_TRIGGER_CP_UPDATE (for "cross-
 * partition update").
 *
 * Note that we need triggers on foreign tables to be fired in exactly the
 * order they were queued, so that the tuples come out of the tuplestore in
 * the right order.  To ensure that, we forbid deferrable (constraint)
 * triggers on foreign tables.  This also ensures that such triggers do not
 * get deferred into outer trigger query levels, meaning that it's okay to
 * destroy the tuplestore at the end of the query level.
 *
 * Statement-level triggers always bear AFTER_TRIGGER_1CTID, though they
 * require no ctid field.  We lack the flag bit space to neatly represent that
 * distinct case, and it seems unlikely to be worth much trouble.
 *
 * Note: ats_firing_id is initially zero and is set to something else when
 * AFTER_TRIGGER_IN_PROGRESS is set.  It indicates which trigger firing
 * cycle the trigger will be fired in (or was fired in, if DONE is set).
 * Although this is mutable state, we can keep it in AfterTriggerSharedData
 * because all instances of the same type of event in a given event list will
 * be fired at the same time, if they were queued between the same firing
 * cycles.  So we need only ensure that ats_firing_id is zero when attaching
 * a new event to an existing AfterTriggerSharedData record.
 */
typedef uint32 TriggerFlags;

#define AFTER_TRIGGER_OFFSET      0x07FFFFFF  /* must be low-order bits */
#define AFTER_TRIGGER_DONE        0x80000000
#define AFTER_TRIGGER_IN_PROGRESS   0x40000000
/* bits describing the size and tuple sources of this event */
#define AFTER_TRIGGER_FDW_REUSE     0x00000000
#define AFTER_TRIGGER_FDW_FETCH     0x20000000
#define AFTER_TRIGGER_1CTID       0x10000000
#define AFTER_TRIGGER_2CTID       0x30000000
#define AFTER_TRIGGER_CP_UPDATE     0x08000000
#define AFTER_TRIGGER_TUP_BITS      0x38000000
typedef struct AfterTriggerSharedData *AfterTriggerShared;

typedef struct AfterTriggerSharedData
{
  TriggerEvent ats_event;   /* event type indicator, see trigger.h */
  Oid     ats_tgoid;    /* the trigger's ID */
  Oid     ats_relid;    /* the relation it's on */
  Oid     ats_rolid;    /* role to execute the trigger */
  CommandId ats_firing_id;  /* ID for firing cycle */
  struct AfterTriggersTableData *ats_table; /* transition table access */
  Bitmapset  *ats_modifiedcols; /* modified columns */
} AfterTriggerSharedData;

typedef struct AfterTriggerEventData *AfterTriggerEvent;

typedef struct AfterTriggerEventData
{
  TriggerFlags ate_flags;   /* status bits and offset to shared data */
  ItemPointerData ate_ctid1;  /* inserted, deleted, or old updated tuple */
  ItemPointerData ate_ctid2;  /* new updated tuple */

  /*
   * During a cross-partition update of a partitioned table, we also store
   * the OIDs of source and destination partitions that are needed to fetch
   * the old (ctid1) and the new tuple (ctid2) from, respectively.
   */
  Oid     ate_src_part;
  Oid     ate_dst_part;
} AfterTriggerEventData;

/* AfterTriggerEventData, minus ate_src_part, ate_dst_part */
typedef struct AfterTriggerEventDataNoOids
{
  TriggerFlags ate_flags;
  ItemPointerData ate_ctid1;
  ItemPointerData ate_ctid2;
}     AfterTriggerEventDataNoOids;

/* AfterTriggerEventData, minus ate_*_part and ate_ctid2 */
typedef struct AfterTriggerEventDataOneCtid
{
  TriggerFlags ate_flags;   /* status bits and offset to shared data */
  ItemPointerData ate_ctid1;  /* inserted, deleted, or old updated tuple */
}     AfterTriggerEventDataOneCtid;

/* AfterTriggerEventData, minus ate_*_part, ate_ctid1 and ate_ctid2 */
typedef struct AfterTriggerEventDataZeroCtids
{
  TriggerFlags ate_flags;   /* status bits and offset to shared data */
}     AfterTriggerEventDataZeroCtids;

#define SizeofTriggerEvent(evt) \
  (((evt)->ate_flags & AFTER_TRIGGER_TUP_BITS) == AFTER_TRIGGER_CP_UPDATE ? \
   sizeof(AfterTriggerEventData) : \
   (((evt)->ate_flags & AFTER_TRIGGER_TUP_BITS) == AFTER_TRIGGER_2CTID ? \
    sizeof(AfterTriggerEventDataNoOids) : \
    (((evt)->ate_flags & AFTER_TRIGGER_TUP_BITS) == AFTER_TRIGGER_1CTID ? \
     sizeof(AfterTriggerEventDataOneCtid) : \
     sizeof(AfterTriggerEventDataZeroCtids))))

#define GetTriggerSharedData(evt) \
  ((AfterTriggerShared) ((char *) (evt) + ((evt)->ate_flags & AFTER_TRIGGER_OFFSET)))

/*
 * To avoid palloc overhead, we keep trigger events in arrays in successively-
 * larger chunks (a slightly more sophisticated version of an expansible
 * array).  The space between CHUNK_DATA_START and freeptr is occupied by
 * AfterTriggerEventData records; the space between endfree and endptr is
 * occupied by AfterTriggerSharedData records.
 */
typedef struct AfterTriggerEventChunk
{
  struct AfterTriggerEventChunk *next;  /* list link */
  char     *freeptr;    /* start of free space in chunk */
  char     *endfree;    /* end of free space in chunk */
  char     *endptr;     /* end of chunk */
  /* event data follows here */
} AfterTriggerEventChunk;

#define CHUNK_DATA_START(cptr) ((char *) (cptr) + MAXALIGN(sizeof(AfterTriggerEventChunk)))

/* A list of events */
typedef struct AfterTriggerEventList
{
  AfterTriggerEventChunk *head;
  AfterTriggerEventChunk *tail;
  char     *tailfree;   /* freeptr of tail chunk */
} AfterTriggerEventList;

/* Macros to help in iterating over a list of events */
#define for_each_chunk(cptr, evtlist) \
  for (cptr = (evtlist).head; cptr != NULL; cptr = cptr->next)
#define for_each_event(eptr, cptr) \
  for (eptr = (AfterTriggerEvent) CHUNK_DATA_START(cptr); \
     (char *) eptr < (cptr)->freeptr; \
     eptr = (AfterTriggerEvent) (((char *) eptr) + SizeofTriggerEvent(eptr)))
/* Use this if no special per-chunk processing is needed */
#define for_each_event_chunk(eptr, cptr, evtlist) \
  for_each_chunk(cptr, evtlist) for_each_event(eptr, cptr)

/* Macros for iterating from a start point that might not be list start */
#define for_each_chunk_from(cptr) \
  for (; cptr != NULL; cptr = cptr->next)
#define for_each_event_from(eptr, cptr) \
  for (; \
     (char *) eptr < (cptr)->freeptr; \
     eptr = (AfterTriggerEvent) (((char *) eptr) + SizeofTriggerEvent(eptr)))


/*
 * All per-transaction data for the AFTER TRIGGERS module.
 *
 * AfterTriggersData has the following fields:
 *
 * firing_counter is incremented for each call of afterTriggerInvokeEvents.
 * We mark firable events with the current firing cycle's ID so that we can
 * tell which ones to work on.  This ensures sane behavior if a trigger
 * function chooses to do SET CONSTRAINTS: the inner SET CONSTRAINTS will
 * only fire those events that weren't already scheduled for firing.
 *
 * state keeps track of the transaction-local effects of SET CONSTRAINTS.
 * This is saved and restored across failed subtransactions.
 *
 * events is the current list of deferred events.  This is global across
 * all subtransactions of the current transaction.  In a subtransaction
 * abort, we know that the events added by the subtransaction are at the
 * end of the list, so it is relatively easy to discard them.  The event
 * list chunks themselves are stored in event_cxt.
 *
 * query_depth is the current depth of nested AfterTriggerBeginQuery calls
 * (-1 when the stack is empty).
 *
 * query_stack[query_depth] is the per-query-level data, including these fields:
 *
 * events is a list of AFTER trigger events queued by the current query.
 * None of these are valid until the matching AfterTriggerEndQuery call
 * occurs.  At that point we fire immediate-mode triggers, and append any
 * deferred events to the main events list.
 *
 * fdw_tuplestore is a tuplestore containing the foreign-table tuples
 * needed by events queued by the current query.  (Note: we use just one
 * tuplestore even though more than one foreign table might be involved.
 * This is okay because tuplestores don't really care what's in the tuples
 * they store; but it's possible that someday it'd break.)
 *
 * tables is a List of AfterTriggersTableData structs for target tables
 * of the current query (see below).
 *
 * maxquerydepth is just the allocated length of query_stack.
 *
 * trans_stack holds per-subtransaction data, including these fields:
 *
 * state is NULL or a pointer to a saved copy of the SET CONSTRAINTS
 * state data.  Each subtransaction level that modifies that state first
 * saves a copy, which we use to restore the state if we abort.
 *
 * events is a copy of the events head/tail pointers,
 * which we use to restore those values during subtransaction abort.
 *
 * query_depth is the subtransaction-start-time value of query_depth,
 * which we similarly use to clean up at subtransaction abort.
 *
 * firing_counter is the subtransaction-start-time value of firing_counter.
 * We use this to recognize which deferred triggers were fired (or marked
 * for firing) within an aborted subtransaction.
 *
 * We use GetCurrentTransactionNestLevel() to determine the correct array
 * index in trans_stack.  maxtransdepth is the number of allocated entries in
 * trans_stack.  (By not keeping our own stack pointer, we can avoid trouble
 * in cases where errors during subxact abort cause multiple invocations
 * of AfterTriggerEndSubXact() at the same nesting depth.)
 *
 * We create an AfterTriggersTableData struct for each target table of the
 * current query, and each operation mode (INSERT/UPDATE/DELETE), that has
 * either transition tables or statement-level triggers.  This is used to
 * hold the relevant transition tables, as well as info tracking whether
 * we already queued the statement triggers.  (We use that info to prevent
 * firing the same statement triggers more than once per statement, or really
 * once per transition table set.)  These structs, along with the transition
 * table tuplestores, live in the (sub)transaction's CurTransactionContext.
 * That's sufficient lifespan because we don't allow transition tables to be
 * used by deferrable triggers, so they only need to survive until
 * AfterTriggerEndQuery.
 */
typedef struct AfterTriggersQueryData AfterTriggersQueryData;
typedef struct AfterTriggersTransData AfterTriggersTransData;
typedef struct AfterTriggersTableData AfterTriggersTableData;

typedef struct AfterTriggersData
{
  CommandId firing_counter; /* next firing ID to assign */
  SetConstraintState state; /* the active S C state */
  AfterTriggerEventList events; /* deferred-event list */
  MemoryContext event_cxt;  /* memory context for events, if any */

  /* per-query-level data: */
  AfterTriggersQueryData *query_stack;  /* array of structs shown below */
  int     query_depth;  /* current index in above array */
  int     maxquerydepth;  /* allocated len of above array */

  /* per-subtransaction-level data: */
  AfterTriggersTransData *trans_stack;  /* array of structs shown below */
  int     maxtransdepth;  /* allocated len of above array */

  List     *batch_callbacks;  /* List of AfterTriggerCallbackItem; for
                   * deferred constraints */
  bool    firing_batch_callbacks; /* true when in
                     * FireAfterTriggerBatchCallbacks() */

  /*
   * Incremented around the trigger-firing loops in AfterTriggerEndQuery,
   * AfterTriggerFireDeferred, and AfterTriggerSetState.  Used by
   * AfterTriggerIsActive() to signal that after-trigger firing is active.
   */
  int     firing_depth;
} AfterTriggersData;

struct AfterTriggersQueryData
{
  AfterTriggerEventList events; /* events pending from this query */
  Tuplestorestate *fdw_tuplestore;  /* foreign tuples for said events */
  List     *tables;     /* list of AfterTriggersTableData, see below */
  List     *batch_callbacks;  /* List of AfterTriggerCallbackItem */
};

struct AfterTriggersTransData
{
  /* these fields are just for resetting at subtrans abort: */
  SetConstraintState state; /* saved S C state, or NULL if not yet saved */
  AfterTriggerEventList events; /* saved list pointer */
  int     query_depth;  /* saved query_depth */
  CommandId firing_counter; /* saved firing_counter */
};

struct AfterTriggersTableData
{
  /* relid + cmdType form the lookup key for these structs: */
  Oid     relid;      /* target table's OID */
  CmdType   cmdType;    /* event type, CMD_INSERT/UPDATE/DELETE */
  bool    closed;     /* true when no longer OK to add tuples */
  bool    before_trig_done; /* did we already queue BS triggers? */
  bool    after_trig_done;  /* did we already queue AS triggers? */
  AfterTriggerEventList after_trig_events;  /* if so, saved list pointer */

  /* "old" transition table for UPDATE/DELETE, if any */
  Tuplestorestate *old_tuplestore;
  /* "new" transition table for INSERT/UPDATE, if any */
  Tuplestorestate *new_tuplestore;

  TupleTableSlot *storeslot;  /* for converting to tuplestore's format */
};

/* Entry in afterTriggers.batch_callbacks */
typedef struct AfterTriggerCallbackItem
{
  AfterTriggerBatchCallback callback;
  void     *arg;
} AfterTriggerCallbackItem;

static AfterTriggersData afterTriggers;

static void AfterTriggerExecute(EState *estate,
                AfterTriggerEvent event,
                ResultRelInfo *relInfo,
                ResultRelInfo *src_relInfo,
                ResultRelInfo *dst_relInfo,
                TriggerDesc *trigdesc,
                FmgrInfo *finfo,
                TriggerInstrumentation *instr,
                MemoryContext per_tuple_context,
                TupleTableSlot *trig_tuple_slot1,
                TupleTableSlot *trig_tuple_slot2);
static AfterTriggersTableData *GetAfterTriggersTableData(Oid relid,
                             CmdType cmdType);
static TupleTableSlot *GetAfterTriggersStoreSlot(AfterTriggersTableData *table,
                         TupleDesc tupdesc);
static Tuplestorestate *GetAfterTriggersTransitionTable(int event,
                            TupleTableSlot *oldslot,
                            TupleTableSlot *newslot,
                            TransitionCaptureState *transition_capture);
static void TransitionTableAddTuple(EState *estate,
                  int event,
                  TransitionCaptureState *transition_capture,
                  ResultRelInfo *relinfo,
                  TupleTableSlot *slot,
                  TupleTableSlot *original_insert_tuple,
                  Tuplestorestate *tuplestore);
static void AfterTriggerFreeQuery(AfterTriggersQueryData *qs);
static SetConstraintState SetConstraintStateCreate(int numalloc);
static SetConstraintState SetConstraintStateCopy(SetConstraintState origstate);
static SetConstraintState SetConstraintStateAddItem(SetConstraintState state,
                          Oid tgoid, bool tgisdeferred);
static void cancel_prior_stmt_triggers(Oid relid, CmdType cmdType, int tgevent);

static void FireAfterTriggerBatchCallbacks(List *callbacks);

/*
 * Get the FDW tuplestore for the current trigger query level, creating it
 * if necessary.
 */
static Tuplestorestate *
GetCurrentFDWTuplestore(void)
{
  Tuplestorestate *ret;

  ret = afterTriggers.query_stack[afterTriggers.query_depth].fdw_tuplestore;
  if (ret == NULL)
  {
    MemoryContext oldcxt;
    ResourceOwner saveResourceOwner;

    /*
     * Make the tuplestore valid until end of subtransaction.  We really
     * only need it until AfterTriggerEndQuery().
     */
    oldcxt = MemoryContextSwitchTo(CurTransactionContext);
    saveResourceOwner = CurrentResourceOwner;
    CurrentResourceOwner = CurTransactionResourceOwner;

    ret = tuplestore_begin_heap(false, false, work_mem);

    CurrentResourceOwner = saveResourceOwner;
    MemoryContextSwitchTo(oldcxt);

    afterTriggers.query_stack[afterTriggers.query_depth].fdw_tuplestore = ret;
  }

  return ret;
}

/* ----------
 * afterTriggerCheckState()
 *
 *  Returns true if the trigger event is actually in state DEFERRED.
 * ----------
 */
static bool
afterTriggerCheckState(AfterTriggerShared evtshared)
{
  Oid     tgoid = evtshared->ats_tgoid;
  SetConstraintState state = afterTriggers.state;
  int     i;

  /*
   * For not-deferrable triggers (i.e. normal AFTER ROW triggers and
   * constraints declared NOT DEFERRABLE), the state is always false.
   */
  if ((evtshared->ats_event & AFTER_TRIGGER_DEFERRABLE) == 0)
    return false;

  /*
   * If constraint state exists, SET CONSTRAINTS might have been executed
   * either for this trigger or for all triggers.
   */
  if (state != NULL)
  {
    /* Check for SET CONSTRAINTS for this specific trigger. */
    for (i = 0; i < state->numstates; i++)
    {
      if (state->trigstates[i].sct_tgoid == tgoid)
        return state->trigstates[i].sct_tgisdeferred;
    }

    /* Check for SET CONSTRAINTS ALL. */
    if (state->all_isset)
      return state->all_isdeferred;
  }

  /*
   * Otherwise return the default state for the trigger.
   */
  return ((evtshared->ats_event & AFTER_TRIGGER_INITDEFERRED) != 0);
}

/* ----------
 * afterTriggerCopyBitmap()
 *
 * Copy bitmap into AfterTriggerEvents memory context, which is where the after
 * trigger events are kept.
 * ----------
 */
static Bitmapset *
afterTriggerCopyBitmap(Bitmapset *src)
{
  Bitmapset  *dst;
  MemoryContext oldcxt;

  if (src == NULL)
    return NULL;

  oldcxt = MemoryContextSwitchTo(afterTriggers.event_cxt);

  dst = bms_copy(src);

  MemoryContextSwitchTo(oldcxt);

  return dst;
}

/* ----------
 * afterTriggerAddEvent()
 *
 *  Add a new trigger event to the specified queue.
 *  The passed-in event data is copied.
 * ----------
 */
static void
afterTriggerAddEvent(AfterTriggerEventList *events,
           AfterTriggerEvent event, AfterTriggerShared evtshared)
{
  Size    eventsize = SizeofTriggerEvent(event);
  Size    needed = eventsize + sizeof(AfterTriggerSharedData);
  AfterTriggerEventChunk *chunk;
  AfterTriggerShared newshared;
  AfterTriggerEvent newevent;

  /*
   * If empty list or not enough room in the tail chunk, make a new chunk.
   * We assume here that a new shared record will always be needed.
   */
  chunk = events->tail;
  if (chunk == NULL ||
    chunk->endfree - chunk->freeptr < needed)
  {
    Size    chunksize;

    /* Create event context if we didn't already */
    if (afterTriggers.event_cxt == NULL)
      afterTriggers.event_cxt =
        AllocSetContextCreate(TopTransactionContext,
                    "AfterTriggerEvents",
                    ALLOCSET_DEFAULT_SIZES);

    /*
     * Chunk size starts at 1KB and is allowed to increase up to 1MB.
     * These numbers are fairly arbitrary, though there is a hard limit at
     * AFTER_TRIGGER_OFFSET; else we couldn't link event records to their
     * shared records using the available space in ate_flags.  Another
     * constraint is that if the chunk size gets too huge, the search loop
     * below would get slow given a (not too common) usage pattern with
     * many distinct event types in a chunk.  Therefore, we double the
     * preceding chunk size only if there weren't too many shared records
     * in the preceding chunk; otherwise we halve it.  This gives us some
     * ability to adapt to the actual usage pattern of the current query
     * while still having large chunk sizes in typical usage.  All chunk
     * sizes used should be MAXALIGN multiples, to ensure that the shared
     * records will be aligned safely.
     */
#define MIN_CHUNK_SIZE 1024
#define MAX_CHUNK_SIZE (1024*1024)

#if MAX_CHUNK_SIZE > (AFTER_TRIGGER_OFFSET+1)
#error MAX_CHUNK_SIZE must not exceed AFTER_TRIGGER_OFFSET
#endif

    if (chunk == NULL)
      chunksize = MIN_CHUNK_SIZE;
    else
    {
      /* preceding chunk size... */
      chunksize = chunk->endptr - (char *) chunk;
      /* check number of shared records in preceding chunk */
      if ((chunk->endptr - chunk->endfree) <=
        (100 * sizeof(AfterTriggerSharedData)))
        chunksize *= 2; /* okay, double it */
      else
        chunksize /= 2; /* too many shared records */
      chunksize = Min(chunksize, MAX_CHUNK_SIZE);
    }
    chunk = MemoryContextAlloc(afterTriggers.event_cxt, chunksize);
    chunk->next = NULL;
    chunk->freeptr = CHUNK_DATA_START(chunk);
    chunk->endptr = chunk->endfree = (char *) chunk + chunksize;
    Assert(chunk->endfree - chunk->freeptr >= needed);

    if (events->tail == NULL)
    {
      Assert(events->head == NULL);
      events->head = chunk;
    }
    else
      events->tail->next = chunk;
    events->tail = chunk;
    /* events->tailfree is now out of sync, but we'll fix it below */
  }

  /*
   * Try to locate a matching shared-data record already in the chunk. If
   * none, make a new one. The search begins with the most recently added
   * record, since newer ones are most likely to match.
   */
  for (newshared = (AfterTriggerShared) chunk->endfree;
     (char *) newshared < chunk->endptr;
     newshared++)
  {
    /* compare fields roughly by probability of them being different */
    if (newshared->ats_tgoid == evtshared->ats_tgoid &&
      newshared->ats_event == evtshared->ats_event &&
      newshared->ats_firing_id == 0 &&
      newshared->ats_table == evtshared->ats_table &&
      newshared->ats_relid == evtshared->ats_relid &&
      newshared->ats_rolid == evtshared->ats_rolid &&
      bms_equal(newshared->ats_modifiedcols,
            evtshared->ats_modifiedcols))
      break;
  }
  if ((char *) newshared >= chunk->endptr)
  {
    newshared = ((AfterTriggerShared) chunk->endfree) - 1;
    *newshared = *evtshared;
    /* now we must make a suitably-long-lived copy of the bitmap */
    newshared->ats_modifiedcols = afterTriggerCopyBitmap(evtshared->ats_modifiedcols);
    newshared->ats_firing_id = 0; /* just to be sure */
    chunk->endfree = (char *) newshared;
  }

  /* Insert the data */
  newevent = (AfterTriggerEvent) chunk->freeptr;
  memcpy(newevent, event, eventsize);
  /* ... and link the new event to its shared record */
  newevent->ate_flags &= ~AFTER_TRIGGER_OFFSET;
  newevent->ate_flags |= (char *) newshared - (char *) newevent;

  chunk->freeptr += eventsize;
  events->tailfree = chunk->freeptr;
}

/* ----------
 * afterTriggerFreeEventList()
 *
 *  Free all the event storage in the given list.
 * ----------
 */
static void
afterTriggerFreeEventList(AfterTriggerEventList *events)
{
  AfterTriggerEventChunk *chunk;

  while ((chunk = events->head) != NULL)
  {
    events->head = chunk->next;
    pfree(chunk);
  }
  events->tail = NULL;
  events->tailfree = NULL;
}

/* ----------
 * afterTriggerRestoreEventList()
 *
 *  Restore an event list to its prior length, removing all the events
 *  added since it had the value old_events.
 * ----------
 */
static void
afterTriggerRestoreEventList(AfterTriggerEventList *events,
               const AfterTriggerEventList *old_events)
{
  AfterTriggerEventChunk *chunk;
  AfterTriggerEventChunk *next_chunk;

  if (old_events->tail == NULL)
  {
    /* restoring to a completely empty state, so free everything */
    afterTriggerFreeEventList(events);
  }
  else
  {
    *events = *old_events;
    /* free any chunks after the last one we want to keep */
    for (chunk = events->tail->next; chunk != NULL; chunk = next_chunk)
    {
      next_chunk = chunk->next;
      pfree(chunk);
    }
    /* and clean up the tail chunk to be the right length */
    events->tail->next = NULL;
    events->tail->freeptr = events->tailfree;

    /*
     * We don't make any effort to remove now-unused shared data records.
     * They might still be useful, anyway.
     */
  }
}

/* ----------
 * afterTriggerDeleteHeadEventChunk()
 *
 *  Remove the first chunk of events from the query level's event list.
 *  Keep any event list pointers elsewhere in the query level's data
 *  structures in sync.
 * ----------
 */
static void
afterTriggerDeleteHeadEventChunk(AfterTriggersQueryData *qs)
{
  AfterTriggerEventChunk *target = qs->events.head;
  ListCell   *lc;

  Assert(target && target->next);

  /*
   * First, update any pointers in the per-table data, so that they won't be
   * dangling.  Resetting obsoleted pointers to NULL will make
   * cancel_prior_stmt_triggers start from the list head, which is fine.
   */
  foreach(lc, qs->tables)
  {
    AfterTriggersTableData *table = (AfterTriggersTableData *) lfirst(lc);

    if (table->after_trig_done &&
      table->after_trig_events.tail == target)
    {
      table->after_trig_events.head = NULL;
      table->after_trig_events.tail = NULL;
      table->after_trig_events.tailfree = NULL;
    }
  }

  /* Now we can flush the head chunk */
  qs->events.head = target->next;
  pfree(target);
}


/* ----------
 * AfterTriggerExecute()
 *
 *  Fetch the required tuples back from the heap and fire one
 *  single trigger function.
 *
 *  Frequently, this will be fired many times in a row for triggers of
 *  a single relation.  Therefore, we cache the open relation and provide
 *  fmgr lookup cache space at the caller level.  (For triggers fired at
 *  the end of a query, we can even piggyback on the executor's state.)
 *
 *  When fired for a cross-partition update of a partitioned table, the old
 *  tuple is fetched using 'src_relInfo' (the source leaf partition) and
 *  the new tuple using 'dst_relInfo' (the destination leaf partition), though
 *  both are converted into the root partitioned table's format before passing
 *  to the trigger function.
 *
 *  event: event currently being fired.
 *  relInfo: result relation for event.
 *  src_relInfo: source partition of a cross-partition update
 *  dst_relInfo: its destination partition
 *  trigdesc: working copy of rel's trigger info.
 *  finfo: array of fmgr lookup cache entries (one per trigger in trigdesc).
 *  instr: array of EXPLAIN ANALYZE instrumentation nodes (one per trigger),
 *    or NULL if no instrumentation is wanted.
 *  per_tuple_context: memory context to call trigger function in.
 *  trig_tuple_slot1: scratch slot for tg_trigtuple (foreign tables only)
 *  trig_tuple_slot2: scratch slot for tg_newtuple (foreign tables only)
 * ----------
 */
static void
AfterTriggerExecute(EState *estate,
          AfterTriggerEvent event,
          ResultRelInfo *relInfo,
          ResultRelInfo *src_relInfo,
          ResultRelInfo *dst_relInfo,
          TriggerDesc *trigdesc,
          FmgrInfo *finfo, TriggerInstrumentation *instr,
          MemoryContext per_tuple_context,
          TupleTableSlot *trig_tuple_slot1,
          TupleTableSlot *trig_tuple_slot2)
{
  Relation  rel = relInfo->ri_RelationDesc;
  Relation  src_rel = src_relInfo->ri_RelationDesc;
  Relation  dst_rel = dst_relInfo->ri_RelationDesc;
  AfterTriggerShared evtshared = GetTriggerSharedData(event);
  Oid     tgoid = evtshared->ats_tgoid;
  TriggerData LocTriggerData = {0};
  Oid     save_rolid;
  int     save_sec_context;
  HeapTuple rettuple;
  int     tgindx;
  bool    should_free_trig = false;
  bool    should_free_new = false;

  /*
   * Locate trigger in trigdesc.  It might not be present, and in fact the
   * trigdesc could be NULL, if the trigger was dropped since the event was
   * queued.  In that case, silently do nothing.
   */
  if (trigdesc == NULL)
    return;
  for (tgindx = 0; tgindx < trigdesc->numtriggers; tgindx++)
  {
    if (trigdesc->triggers[tgindx].tgoid == tgoid)
    {
      LocTriggerData.tg_trigger = &(trigdesc->triggers[tgindx]);
      break;
    }
  }
  if (LocTriggerData.tg_trigger == NULL)
    return;

  /*
   * If doing EXPLAIN ANALYZE, start charging time to this trigger. We want
   * to include time spent re-fetching tuples in the trigger cost.
   */
  if (instr)
    InstrStartTrigger(instr + tgindx);

  /*
   * Fetch the required tuple(s).
   */
  switch (event->ate_flags & AFTER_TRIGGER_TUP_BITS)
  {
    case AFTER_TRIGGER_FDW_FETCH:
      {
        Tuplestorestate *fdw_tuplestore = GetCurrentFDWTuplestore();

        if (!tuplestore_gettupleslot(fdw_tuplestore, true, false,
                       trig_tuple_slot1))
          elog(ERROR, "failed to fetch tuple1 for AFTER trigger");

        if ((evtshared->ats_event & TRIGGER_EVENT_OPMASK) ==
          TRIGGER_EVENT_UPDATE &&
          !tuplestore_gettupleslot(fdw_tuplestore, true, false,
                       trig_tuple_slot2))
          elog(ERROR, "failed to fetch tuple2 for AFTER trigger");
      }
      pg_fallthrough;
    case AFTER_TRIGGER_FDW_REUSE:

      /*
       * Store tuple in the slot so that tg_trigtuple does not reference
       * tuplestore memory.  (It is formally possible for the trigger
       * function to queue trigger events that add to the same
       * tuplestore, which can push other tuples out of memory.)  The
       * distinction is academic, because we start with a minimal tuple
       * that is stored as a heap tuple, constructed in different memory
       * context, in the slot anyway.
       */
      LocTriggerData.tg_trigslot = trig_tuple_slot1;
      LocTriggerData.tg_trigtuple =
        ExecFetchSlotHeapTuple(trig_tuple_slot1, true, &should_free_trig);

      if ((evtshared->ats_event & TRIGGER_EVENT_OPMASK) ==
        TRIGGER_EVENT_UPDATE)
      {
        LocTriggerData.tg_newslot = trig_tuple_slot2;
        LocTriggerData.tg_newtuple =
          ExecFetchSlotHeapTuple(trig_tuple_slot2, true, &should_free_new);
      }
      else
      {
        LocTriggerData.tg_newtuple = NULL;
      }
      break;

    default:
      if (ItemPointerIsValid(&(event->ate_ctid1)))
      {
        TupleTableSlot *src_slot = ExecGetTriggerOldSlot(estate,
                                 src_relInfo);

        if (!table_tuple_fetch_row_version(src_rel,
                           &(event->ate_ctid1),
                           SnapshotAny,
                           src_slot))
          elog(ERROR, "failed to fetch tuple1 for AFTER trigger");

        /*
         * Store the tuple fetched from the source partition into the
         * target (root partitioned) table slot, converting if needed.
         */
        if (src_relInfo != relInfo)
        {
          TupleConversionMap *map = ExecGetChildToRootMap(src_relInfo);

          LocTriggerData.tg_trigslot = ExecGetTriggerOldSlot(estate, relInfo);
          if (map)
          {
            execute_attr_map_slot(map->attrMap,
                        src_slot,
                        LocTriggerData.tg_trigslot);
          }
          else
            ExecCopySlot(LocTriggerData.tg_trigslot, src_slot);
        }
        else
          LocTriggerData.tg_trigslot = src_slot;
        LocTriggerData.tg_trigtuple =
          ExecFetchSlotHeapTuple(LocTriggerData.tg_trigslot, false, &should_free_trig);
      }
      else
      {
        LocTriggerData.tg_trigtuple = NULL;
      }

      /* don't touch ctid2 if not there */
      if (((event->ate_flags & AFTER_TRIGGER_TUP_BITS) == AFTER_TRIGGER_2CTID ||
         (event->ate_flags & AFTER_TRIGGER_CP_UPDATE)) &&
        ItemPointerIsValid(&(event->ate_ctid2)))
      {
        TupleTableSlot *dst_slot = ExecGetTriggerNewSlot(estate,
                                 dst_relInfo);

        if (!table_tuple_fetch_row_version(dst_rel,
                           &(event->ate_ctid2),
                           SnapshotAny,
                           dst_slot))
          elog(ERROR, "failed to fetch tuple2 for AFTER trigger");

        /*
         * Store the tuple fetched from the destination partition into
         * the target (root partitioned) table slot, converting if
         * needed.
         */
        if (dst_relInfo != relInfo)
        {
          TupleConversionMap *map = ExecGetChildToRootMap(dst_relInfo);

          LocTriggerData.tg_newslot = ExecGetTriggerNewSlot(estate, relInfo);
          if (map)
          {
            execute_attr_map_slot(map->attrMap,
                        dst_slot,
                        LocTriggerData.tg_newslot);
          }
          else
            ExecCopySlot(LocTriggerData.tg_newslot, dst_slot);
        }
        else
          LocTriggerData.tg_newslot = dst_slot;
        LocTriggerData.tg_newtuple =
          ExecFetchSlotHeapTuple(LocTriggerData.tg_newslot, false, &should_free_new);
      }
      else
      {
        LocTriggerData.tg_newtuple = NULL;
      }
  }

  /*
   * Set up the tuplestore information to let the trigger have access to
   * transition tables.  When we first make a transition table available to
   * a trigger, mark it "closed" so that it cannot change anymore.  If any
   * additional events of the same type get queued in the current trigger
   * query level, they'll go into new transition tables.
   */
  LocTriggerData.tg_oldtable = LocTriggerData.tg_newtable = NULL;
  if (evtshared->ats_table)
  {
    if (LocTriggerData.tg_trigger->tgoldtable)
    {
      LocTriggerData.tg_oldtable = evtshared->ats_table->old_tuplestore;
      evtshared->ats_table->closed = true;
    }

    if (LocTriggerData.tg_trigger->tgnewtable)
    {
      LocTriggerData.tg_newtable = evtshared->ats_table->new_tuplestore;
      evtshared->ats_table->closed = true;
    }
  }

  /*
   * Setup the remaining trigger information
   */
  LocTriggerData.type = T_TriggerData;
  LocTriggerData.tg_event =
    evtshared->ats_event & (TRIGGER_EVENT_OPMASK | TRIGGER_EVENT_ROW);
  LocTriggerData.tg_relation = rel;
  if (TRIGGER_FOR_UPDATE(LocTriggerData.tg_trigger->tgtype))
    LocTriggerData.tg_updatedcols = evtshared->ats_modifiedcols;

  MemoryContextReset(per_tuple_context);

  /*
   * If necessary, become the role that was active when the trigger got
   * queued.  Note that the role might have been dropped since the trigger
   * was queued, but if that is a problem, we will get an error later.
   * Checking here would still leave a race condition.
   */
  GetUserIdAndSecContext(&save_rolid, &save_sec_context);
  if (save_rolid != evtshared->ats_rolid)
    SetUserIdAndSecContext(evtshared->ats_rolid,
                 save_sec_context | SECURITY_LOCAL_USERID_CHANGE);

  /*
   * Call the trigger and throw away any possibly returned updated tuple.
   * (Don't let ExecCallTriggerFunc measure EXPLAIN time.)
   */
  rettuple = ExecCallTriggerFunc(&LocTriggerData,
                   tgindx,
                   finfo,
                   NULL,
                   per_tuple_context);
  if (rettuple != NULL &&
    rettuple != LocTriggerData.tg_trigtuple &&
    rettuple != LocTriggerData.tg_newtuple)
    heap_freetuple(rettuple);

  /* Restore the current role if necessary */
  if (save_rolid != evtshared->ats_rolid)
    SetUserIdAndSecContext(save_rolid, save_sec_context);

  /*
   * Release resources
   */
  if (should_free_trig)
    heap_freetuple(LocTriggerData.tg_trigtuple);
  if (should_free_new)
    heap_freetuple(LocTriggerData.tg_newtuple);

  /* don't clear slots' contents if foreign table */
  if (trig_tuple_slot1 == NULL)
  {
    if (LocTriggerData.tg_trigslot)
      ExecClearTuple(LocTriggerData.tg_trigslot);
    if (LocTriggerData.tg_newslot)
      ExecClearTuple(LocTriggerData.tg_newslot);
  }

  /*
   * If doing EXPLAIN ANALYZE, stop charging time to this trigger, and count
   * the firing of the trigger.
   */
  if (instr)
    InstrStopTrigger(instr + tgindx, 1);
}


/*
 * afterTriggerMarkEvents()
 *
 *  Scan the given event list for not yet invoked events.  Mark the ones
 *  that can be invoked now with the current firing ID.
 *
 *  If move_list isn't NULL, events that are not to be invoked now are
 *  transferred to move_list.
 *
 *  When immediate_only is true, do not invoke currently-deferred triggers.
 *  (This will be false only at main transaction exit.)
 *
 *  Returns true if any invokable events were found.
 */
static bool
afterTriggerMarkEvents(AfterTriggerEventList *events,
             AfterTriggerEventList *move_list,
             bool immediate_only)
{
  bool    found = false;
  bool    deferred_found = false;
  AfterTriggerEvent event;
  AfterTriggerEventChunk *chunk;

  for_each_event_chunk(event, chunk, *events)
  {
    AfterTriggerShared evtshared = GetTriggerSharedData(event);
    bool    defer_it = false;

    if (!(event->ate_flags &
        (AFTER_TRIGGER_DONE | AFTER_TRIGGER_IN_PROGRESS)))
    {
      /*
       * This trigger hasn't been called or scheduled yet. Check if we
       * should call it now.
       */
      if (immediate_only && afterTriggerCheckState(evtshared))
      {
        defer_it = true;
      }
      else
      {
        /*
         * Mark it as to be fired in this firing cycle.
         */
        evtshared->ats_firing_id = afterTriggers.firing_counter;
        event->ate_flags |= AFTER_TRIGGER_IN_PROGRESS;
        found = true;
      }
    }

    /*
     * If it's deferred, move it to move_list, if requested.
     */
    if (defer_it && move_list != NULL)
    {
      deferred_found = true;
      /* add it to move_list */
      afterTriggerAddEvent(move_list, event, evtshared);
      /* mark original copy "done" so we don't do it again */
      event->ate_flags |= AFTER_TRIGGER_DONE;
    }
  }

  /*
   * We could allow deferred triggers if, before the end of the
   * security-restricted operation, we were to verify that a SET CONSTRAINTS
   * ... IMMEDIATE has fired all such triggers.  For now, don't bother.
   */
  if (deferred_found && InSecurityRestrictedOperation())
    ereport(ERROR,
        (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
         errmsg("cannot fire deferred trigger within security-restricted operation")));

  return found;
}

/*
 * afterTriggerInvokeEvents()
 *
 *  Scan the given event list for events that are marked as to be fired
 *  in the current firing cycle, and fire them.
 *
 *  If estate isn't NULL, we use its result relation info to avoid repeated
 *  openings and closing of trigger target relations.  If it is NULL, we
 *  make one locally to cache the info in case there are multiple trigger
 *  events per rel.
 *
 *  When delete_ok is true, it's safe to delete fully-processed events.
 *  (We are not very tense about that: we simply reset a chunk to be empty
 *  if all its events got fired.  The objective here is just to avoid useless
 *  rescanning of events when a trigger queues new events during transaction
 *  end, so it's not necessary to worry much about the case where only
 *  some events are fired.)
 *
 *  Returns true if no unfired events remain in the list (this allows us
 *  to avoid repeating afterTriggerMarkEvents).
 */
static bool
afterTriggerInvokeEvents(AfterTriggerEventList *events,
             CommandId firing_id,
             EState *estate,
             bool delete_ok)
{
  bool    all_fired = true;
  AfterTriggerEventChunk *chunk;
  MemoryContext per_tuple_context;
  bool    local_estate = false;
  ResultRelInfo *rInfo = NULL;
  Relation  rel = NULL;
  TriggerDesc *trigdesc = NULL;
  FmgrInfo   *finfo = NULL;
  TriggerInstrumentation *instr = NULL;
  TupleTableSlot *slot1 = NULL,
         *slot2 = NULL;

  /* Make a local EState if need be */
  if (estate == NULL)
  {
    estate = CreateExecutorState();
    local_estate = true;
  }

  /* Make a per-tuple memory context for trigger function calls */
  per_tuple_context =
    AllocSetContextCreate(CurrentMemoryContext,
                "AfterTriggerTupleContext",
                ALLOCSET_DEFAULT_SIZES);

  for_each_chunk(chunk, *events)
  {
    AfterTriggerEvent event;
    bool    all_fired_in_chunk = true;

    for_each_event(event, chunk)
    {
      AfterTriggerShared evtshared = GetTriggerSharedData(event);

      /*
       * Is it one for me to fire?
       */
      if ((event->ate_flags & AFTER_TRIGGER_IN_PROGRESS) &&
        evtshared->ats_firing_id == firing_id)
      {
        ResultRelInfo *src_rInfo,
               *dst_rInfo;

        /*
         * So let's fire it... but first, find the correct relation if
         * this is not the same relation as before.
         */
        if (rel == NULL || RelationGetRelid(rel) != evtshared->ats_relid)
        {
          rInfo = ExecGetTriggerResultRel(estate, evtshared->ats_relid,
                          NULL);
          rel = rInfo->ri_RelationDesc;
          /* Catch calls with insufficient relcache refcounting */
          Assert(!RelationHasReferenceCountZero(rel));
          trigdesc = rInfo->ri_TrigDesc;
          /* caution: trigdesc could be NULL here */
          finfo = rInfo->ri_TrigFunctions;
          instr = rInfo->ri_TrigInstrument;
          if (slot1 != NULL)
          {
            ExecDropSingleTupleTableSlot(slot1);
            ExecDropSingleTupleTableSlot(slot2);
            slot1 = slot2 = NULL;
          }
          if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
          {
            slot1 = MakeSingleTupleTableSlot(rel->rd_att,
                             &TTSOpsMinimalTuple);
            slot2 = MakeSingleTupleTableSlot(rel->rd_att,
                             &TTSOpsMinimalTuple);
          }
        }

        /*
         * Look up source and destination partition result rels of a
         * cross-partition update event.
         */
        if ((event->ate_flags & AFTER_TRIGGER_TUP_BITS) ==
          AFTER_TRIGGER_CP_UPDATE)
        {
          Assert(OidIsValid(event->ate_src_part) &&
               OidIsValid(event->ate_dst_part));
          src_rInfo = ExecGetTriggerResultRel(estate,
                            event->ate_src_part,
                            rInfo);
          dst_rInfo = ExecGetTriggerResultRel(estate,
                            event->ate_dst_part,
                            rInfo);
        }
        else
          src_rInfo = dst_rInfo = rInfo;

        /*
         * Fire it.  Note that the AFTER_TRIGGER_IN_PROGRESS flag is
         * still set, so recursive examinations of the event list
         * won't try to re-fire it.
         */
        AfterTriggerExecute(estate, event, rInfo,
                  src_rInfo, dst_rInfo,
                  trigdesc, finfo, instr,
                  per_tuple_context, slot1, slot2);

        /*
         * Mark the event as done.
         */
        event->ate_flags &= ~AFTER_TRIGGER_IN_PROGRESS;
        event->ate_flags |= AFTER_TRIGGER_DONE;
      }
      else if (!(event->ate_flags & AFTER_TRIGGER_DONE))
      {
        /* something remains to be done */
        all_fired = all_fired_in_chunk = false;
      }
    }

    /* Clear the chunk if delete_ok and nothing left of interest */
    if (delete_ok && all_fired_in_chunk)
    {
      chunk->freeptr = CHUNK_DATA_START(chunk);
      chunk->endfree = chunk->endptr;

      /*
       * If it's last chunk, must sync event list's tailfree too.  Note
       * that delete_ok must NOT be passed as true if there could be
       * additional AfterTriggerEventList values pointing at this event
       * list, since we'd fail to fix their copies of tailfree.
       */
      if (chunk == events->tail)
        events->tailfree = chunk->freeptr;
    }
  }
  if (slot1 != NULL)
  {
    ExecDropSingleTupleTableSlot(slot1);
    ExecDropSingleTupleTableSlot(slot2);
  }

  /* Release working resources */
  MemoryContextDelete(per_tuple_context);

  if (local_estate)
  {
    ExecCloseResultRelations(estate);
    ExecResetTupleTable(estate->es_tupleTable, false);
    FreeExecutorState(estate);
  }

  return all_fired;
}


/*
 * GetAfterTriggersTableData
 *
 * Find or create an AfterTriggersTableData struct for the specified
 * trigger event (relation + operation type).  Ignore existing structs
 * marked "closed"; we don't want to put any additional tuples into them,
 * nor change their stmt-triggers-fired state.
 *
 * Note: the AfterTriggersTableData list is allocated in the current
 * (sub)transaction's CurTransactionContext.  This is OK because
 * we don't need it to live past AfterTriggerEndQuery.
 */
static AfterTriggersTableData *
GetAfterTriggersTableData(Oid relid, CmdType cmdType)
{
  AfterTriggersTableData *table;
  AfterTriggersQueryData *qs;
  MemoryContext oldcxt;
  ListCell   *lc;

  /* At this level, cmdType should not be, eg, CMD_MERGE */
  Assert(cmdType == CMD_INSERT ||
       cmdType == CMD_UPDATE ||
       cmdType == CMD_DELETE);

  /* Caller should have ensured query_depth is OK. */
  Assert(afterTriggers.query_depth >= 0 &&
       afterTriggers.query_depth < afterTriggers.maxquerydepth);
  qs = &afterTriggers.query_stack[afterTriggers.query_depth];

  foreach(lc, qs->tables)
  {
    table = (AfterTriggersTableData *) lfirst(lc);
    if (table->relid == relid && table->cmdType == cmdType &&
      !table->closed)
      return table;
  }

  oldcxt = MemoryContextSwitchTo(CurTransactionContext);

  table = palloc0_object(AfterTriggersTableData);
  table->relid = relid;
  table->cmdType = cmdType;
  qs->tables = lappend(qs->tables, table);

  MemoryContextSwitchTo(oldcxt);

  return table;
}

/*
 * Returns a TupleTableSlot suitable for holding the tuples to be put
 * into AfterTriggersTableData's transition table tuplestores.
 */
static TupleTableSlot *
GetAfterTriggersStoreSlot(AfterTriggersTableData *table,
              TupleDesc tupdesc)
{
  /* Create it if not already done. */
  if (!table->storeslot)
  {
    MemoryContext oldcxt;

    /*
     * We need this slot only until AfterTriggerEndQuery, but making it
     * last till end-of-subxact is good enough.  It'll be freed by
     * AfterTriggerFreeQuery().  However, the passed-in tupdesc might have
     * a different lifespan, so we'd better make a copy of that.
     */
    oldcxt = MemoryContextSwitchTo(CurTransactionContext);
    tupdesc = CreateTupleDescCopy(tupdesc);
    table->storeslot = MakeSingleTupleTableSlot(tupdesc, &TTSOpsVirtual);
    MemoryContextSwitchTo(oldcxt);
  }

  return table->storeslot;
}

/*
 * MakeTransitionCaptureState
 *
 * Make a TransitionCaptureState object for the given TriggerDesc, target
 * relation, and operation type.  The TCS object holds all the state needed
 * to decide whether to capture tuples in transition tables.
 *
 * If there are no triggers in 'trigdesc' that request relevant transition
 * tables, then return NULL.
 *
 * The resulting object can be passed to the ExecAR* functions.  When
 * dealing with child tables, the caller can set tcs_original_insert_tuple
 * to avoid having to reconstruct the original tuple in the root table's
 * format.
 *
 * Note that we copy the flags from a parent table into this struct (rather
 * than subsequently using the relation's TriggerDesc directly) so that we can
 * use it to control collection of transition tuples from child tables.
 *
 * Per SQL spec, all operations of the same kind (INSERT/UPDATE/DELETE)
 * on the same table during one query should share one transition table.
 * Therefore, the Tuplestores are owned by an AfterTriggersTableData struct
 * looked up using the table OID + CmdType, and are merely referenced by
 * the TransitionCaptureState objects we hand out to callers.
 */
TransitionCaptureState *
MakeTransitionCaptureState(TriggerDesc *trigdesc, Oid relid, CmdType cmdType)
{
  TransitionCaptureState *state;
  bool    need_old_upd,
        need_new_upd,
        need_old_del,
        need_new_ins;
  AfterTriggersTableData *ins_table;
  AfterTriggersTableData *upd_table;
  AfterTriggersTableData *del_table;
  MemoryContext oldcxt;
  ResourceOwner saveResourceOwner;

  if (trigdesc == NULL)
    return NULL;

  /* Detect which table(s) we need. */
  switch (cmdType)
  {
    case CMD_INSERT:
      need_old_upd = need_old_del = need_new_upd = false;
      need_new_ins = trigdesc->trig_insert_new_table;
      break;
    case CMD_UPDATE:
      need_old_upd = trigdesc->trig_update_old_table;
      need_new_upd = trigdesc->trig_update_new_table;
      need_old_del = need_new_ins = false;
      break;
    case CMD_DELETE:
      need_old_del = trigdesc->trig_delete_old_table;
      need_old_upd = need_new_upd = need_new_ins = false;
      break;
    case CMD_MERGE:
      need_old_upd = trigdesc->trig_update_old_table;
      need_new_upd = trigdesc->trig_update_new_table;
      need_old_del = trigdesc->trig_delete_old_table;
      need_new_ins = trigdesc->trig_insert_new_table;
      break;
    default:
      elog(ERROR, "unexpected CmdType: %d", (int) cmdType);
      /* keep compiler quiet */
      need_old_upd = need_new_upd = need_old_del = need_new_ins = false;
      break;
  }
  if (!need_old_upd && !need_new_upd && !need_new_ins && !need_old_del)
    return NULL;

  /* Check state, like AfterTriggerSaveEvent. */
  if (afterTriggers.query_depth < 0)
    elog(ERROR, "MakeTransitionCaptureState() called outside of query");

  /* Be sure we have enough space to record events at this query depth. */
  if (afterTriggers.query_depth >= afterTriggers.maxquerydepth)
    AfterTriggerEnlargeQueryState();

  /*
   * Find or create AfterTriggersTableData struct(s) to hold the
   * tuplestore(s).  If there's a matching struct but it's marked closed,
   * ignore it; we need a newer one.
   *
   * Note: MERGE must use the same AfterTriggersTableData structs as INSERT,
   * UPDATE, and DELETE, so that any MERGE'd tuples are added to the same
   * tuplestores as tuples from any INSERT, UPDATE, or DELETE commands
   * running in the same top-level command (e.g., in a writable CTE).
   *
   * Note: the AfterTriggersTableData list, as well as the tuplestores, are
   * allocated in the current (sub)transaction's CurTransactionContext, and
   * the tuplestores are managed by the (sub)transaction's resource owner.
   * This is sufficient lifespan because we do not allow triggers using
   * transition tables to be deferrable; they will be fired during
   * AfterTriggerEndQuery, after which it's okay to delete the data.
   */
  if (need_new_ins)
    ins_table = GetAfterTriggersTableData(relid, CMD_INSERT);
  else
    ins_table = NULL;

  if (need_old_upd || need_new_upd)
    upd_table = GetAfterTriggersTableData(relid, CMD_UPDATE);
  else
    upd_table = NULL;

  if (need_old_del)
    del_table = GetAfterTriggersTableData(relid, CMD_DELETE);
  else
    del_table = NULL;

  /* Now create required tuplestore(s), if we don't have them already. */
  oldcxt = MemoryContextSwitchTo(CurTransactionContext);
  saveResourceOwner = CurrentResourceOwner;
  CurrentResourceOwner = CurTransactionResourceOwner;

  if (need_old_upd && upd_table->old_tuplestore == NULL)
    upd_table->old_tuplestore = tuplestore_begin_heap(false, false, work_mem);
  if (need_new_upd && upd_table->new_tuplestore == NULL)
    upd_table->new_tuplestore = tuplestore_begin_heap(false, false, work_mem);
  if (need_old_del && del_table->old_tuplestore == NULL)
    del_table->old_tuplestore = tuplestore_begin_heap(false, false, work_mem);
  if (need_new_ins && ins_table->new_tuplestore == NULL)
    ins_table->new_tuplestore = tuplestore_begin_heap(false, false, work_mem);

  CurrentResourceOwner = saveResourceOwner;
  MemoryContextSwitchTo(oldcxt);

  /* Now build the TransitionCaptureState struct, in caller's context */
  state = palloc0_object(TransitionCaptureState);
  state->tcs_delete_old_table = need_old_del;
  state->tcs_update_old_table = need_old_upd;
  state->tcs_update_new_table = need_new_upd;
  state->tcs_insert_new_table = need_new_ins;
  state->tcs_insert_private = ins_table;
  state->tcs_update_private = upd_table;
  state->tcs_delete_private = del_table;

  return state;
}


/* ----------
 * AfterTriggerBeginXact()
 *
 *  Called at transaction start (either BEGIN or implicit for single
 *  statement outside of transaction block).
 * ----------
 */
void
AfterTriggerBeginXact(void)
{
  /*
   * Initialize after-trigger state structure to empty
   */
  afterTriggers.firing_counter = (CommandId) 1; /* mustn't be 0 */
  afterTriggers.query_depth = -1;
  afterTriggers.firing_depth = 0;
  afterTriggers.batch_callbacks = NIL;
  afterTriggers.firing_batch_callbacks = false;

  /*
   * Verify that there is no leftover state remaining.  If these assertions
   * trip, it means that AfterTriggerEndXact wasn't called or didn't clean
   * up properly.
   */
  Assert(afterTriggers.state == NULL);
  Assert(afterTriggers.query_stack == NULL);
  Assert(afterTriggers.maxquerydepth == 0);
  Assert(afterTriggers.event_cxt == NULL);
  Assert(afterTriggers.events.head == NULL);
  Assert(afterTriggers.trans_stack == NULL);
  Assert(afterTriggers.maxtransdepth == 0);
}


/* ----------
 * AfterTriggerBeginQuery()
 *
 *  Called just before we start processing a single query within a
 *  transaction (or subtransaction).  Most of the real work gets deferred
 *  until somebody actually tries to queue a trigger event.
 * ----------
 */
void
AfterTriggerBeginQuery(void)
{
  /* Increase the query stack depth */
  afterTriggers.query_depth++;
}


/* ----------
 * AfterTriggerEndQuery()
 *
 *  Called after one query has been completely processed. At this time
 *  we invoke all AFTER IMMEDIATE trigger events queued by the query, and
 *  transfer deferred trigger events to the global deferred-trigger list.
 *
 *  Note that this must be called BEFORE closing down the executor
 *  with ExecutorEnd, because we make use of the EState's info about
 *  target relations.  Normally it is called from ExecutorFinish.
 * ----------
 */
void
AfterTriggerEndQuery(EState *estate)
{
  AfterTriggersQueryData *qs;

  /* Must be inside a query, too */
  Assert(afterTriggers.query_depth >= 0);

  /*
   * If we never even got as far as initializing the event stack, there
   * certainly won't be any events, so exit quickly.
   */
  if (afterTriggers.query_depth >= afterTriggers.maxquerydepth)
  {
    afterTriggers.query_depth--;
    return;
  }

  /*
   * Process all immediate-mode triggers queued by the query, and move the
   * deferred ones to the main list of deferred events.
   *
   * Notice that we decide which ones will be fired, and put the deferred
   * ones on the main list, before anything is actually fired.  This ensures
   * reasonably sane behavior if a trigger function does SET CONSTRAINTS ...
   * IMMEDIATE: all events we have decided to defer will be available for it
   * to fire.
   *
   * We loop in case a trigger queues more events at the same query level.
   * Ordinary trigger functions, including all PL/pgSQL trigger functions,
   * will instead fire any triggers in a dedicated query level.  Foreign key
   * enforcement triggers do add to the current query level, thanks to their
   * passing fire_triggers = false to SPI_execute_snapshot().  Other
   * C-language triggers might do likewise.
   *
   * If we find no firable events, we don't have to increment
   * firing_counter.
   */
  qs = &afterTriggers.query_stack[afterTriggers.query_depth];

  afterTriggers.firing_depth++;
  for (;;)
  {
    if (afterTriggerMarkEvents(&qs->events, &afterTriggers.events, true))
    {
      CommandId firing_id = afterTriggers.firing_counter++;
      AfterTriggerEventChunk *oldtail = qs->events.tail;

      if (afterTriggerInvokeEvents(&qs->events, firing_id, estate, false))
        break;     /* all fired */

      /*
       * Firing a trigger could result in query_stack being repalloc'd,
       * so we must recalculate qs after each afterTriggerInvokeEvents
       * call.  Furthermore, it's unsafe to pass delete_ok = true here,
       * because that could cause afterTriggerInvokeEvents to try to
       * access qs->events after the stack has been repalloc'd.
       */
      qs = &afterTriggers.query_stack[afterTriggers.query_depth];

      /*
       * We'll need to scan the events list again.  To reduce the cost
       * of doing so, get rid of completely-fired chunks.  We know that
       * all events were marked IN_PROGRESS or DONE at the conclusion of
       * afterTriggerMarkEvents, so any still-interesting events must
       * have been added after that, and so must be in the chunk that
       * was then the tail chunk, or in later chunks.  So, zap all
       * chunks before oldtail.  This is approximately the same set of
       * events we would have gotten rid of by passing delete_ok = true.
       */
      Assert(oldtail != NULL);
      while (qs->events.head != oldtail)
        afterTriggerDeleteHeadEventChunk(qs);
    }
    else
      break;
  }

  /*
   * Fire batch callbacks before releasing query-level storage and before
   * decrementing query_depth.  Callbacks may do real work (index probes,
   * error reporting).
   *
   * Recompute qs first: the loop above refreshes it after each
   * afterTriggerInvokeEvents() call (see comment there), but the "all
   * fired" break exits without doing so, leaving qs potentially stale here.
   */
  qs = &afterTriggers.query_stack[afterTriggers.query_depth];
  FireAfterTriggerBatchCallbacks(qs->batch_callbacks);

  /* Release query-level-local storage, including tuplestores if any */
  AfterTriggerFreeQuery(&afterTriggers.query_stack[afterTriggers.query_depth]);

  afterTriggers.query_depth--;
  afterTriggers.firing_depth--;
}


/*
 * AfterTriggerFreeQuery
 *  Release subsidiary storage for a trigger query level.
 *  This includes closing down tuplestores.
 *  Note: it's important for this to be safe if interrupted by an error
 *  and then called again for the same query level.
 */
static void
AfterTriggerFreeQuery(AfterTriggersQueryData *qs)
{
  Tuplestorestate *ts;
  List     *tables;
  ListCell   *lc;

  /* Drop the trigger events */
  afterTriggerFreeEventList(&qs->events);

  /* Drop FDW tuplestore if any */
  ts = qs->fdw_tuplestore;
  qs->fdw_tuplestore = NULL;
  if (ts)
    tuplestore_end(ts);

  /* Release per-table subsidiary storage */
  tables = qs->tables;
  foreach(lc, tables)
  {
    AfterTriggersTableData *table = (AfterTriggersTableData *) lfirst(lc);

    ts = table->old_tuplestore;
    table->old_tuplestore = NULL;
    if (ts)
      tuplestore_end(ts);
    ts = table->new_tuplestore;
    table->new_tuplestore = NULL;
    if (ts)
      tuplestore_end(ts);
    if (table->storeslot)
    {
      TupleTableSlot *slot = table->storeslot;

      table->storeslot = NULL;
      ExecDropSingleTupleTableSlot(slot);
    }
  }

  /*
   * Now free the AfterTriggersTableData structs and list cells.  Reset list
   * pointer first; if list_free_deep somehow gets an error, better to leak
   * that storage than have an infinite loop.
   */
  qs->tables = NIL;
  list_free_deep(tables);

  list_free_deep(qs->batch_callbacks);
  qs->batch_callbacks = NIL;
}


/* ----------
 * AfterTriggerFireDeferred()
 *
 *  Called just before the current transaction is committed. At this
 *  time we invoke all pending DEFERRED triggers.
 *
 *  It is possible for other modules to queue additional deferred triggers
 *  during pre-commit processing; therefore xact.c may have to call this
 *  multiple times.
 * ----------
 */
void
AfterTriggerFireDeferred(void)
{
  AfterTriggerEventList *events;
  bool    snap_pushed = false;

  /* Must not be inside a query */
  Assert(afterTriggers.query_depth == -1);

  /*
   * If there are any triggers to fire, make sure we have set a snapshot for
   * them to use.  (Since PortalRunUtility doesn't set a snap for COMMIT, we
   * can't assume ActiveSnapshot is valid on entry.)
   */
  events = &afterTriggers.events;
  if (events->head != NULL)
  {
    PushActiveSnapshot(GetTransactionSnapshot());
    snap_pushed = true;
  }

  /*
   * Run all the remaining triggers.  Loop until they are all gone, in case
   * some trigger queues more for us to do.
   */
  afterTriggers.firing_depth++;
  while (afterTriggerMarkEvents(events, NULL, false))
  {
    CommandId firing_id = afterTriggers.firing_counter++;

    (void) afterTriggerInvokeEvents(events, firing_id, NULL, true);

    /*
     * Flush any fast-path FK-check batches accumulated by the triggers
     * just fired.  A batch callback runs user-supplied cast or equality
     * functions, whose DML can queue further deferred trigger events.
     * Flush inside the loop so afterTriggerMarkEvents() sees any such
     * events on the next iteration and fires them; flushing after the
     * loop would leave them unfired, silently skipping e.g. a deferred FK
     * check and letting a violating row commit.  (The former "all fired"
     * break is therefore gone: the loop now terminates only when
     * afterTriggerMarkEvents() finds nothing left, including events
     * queued by the flush.)
     */
    FireAfterTriggerBatchCallbacks(afterTriggers.batch_callbacks);
  }

  afterTriggers.firing_depth--;

  /*
   * We don't bother freeing the event list or batch_callbacks, since they
   * will go away anyway (and more efficiently than via pfree) in
   * AfterTriggerEndXact.
   */

  if (snap_pushed)
    PopActiveSnapshot();
}


/* ----------
 * AfterTriggerEndXact()
 *
 *  The current transaction is finishing.
 *
 *  Any unfired triggers are canceled so we simply throw
 *  away anything we know.
 *
 *  Note: it is possible for this to be called repeatedly in case of
 *  error during transaction abort; therefore, do not complain if
 *  already closed down.
 * ----------
 */
void
AfterTriggerEndXact(bool isCommit)
{
  /*
   * Forget the pending-events list.
   *
   * Since all the info is in TopTransactionContext or children thereof, we
   * don't really need to do anything to reclaim memory.  However, the
   * pending-events list could be large, and so it's useful to discard it as
   * soon as possible --- especially if we are aborting because we ran out
   * of memory for the list!
   */
  if (afterTriggers.event_cxt)
  {
    MemoryContextDelete(afterTriggers.event_cxt);
    afterTriggers.event_cxt = NULL;
    afterTriggers.events.head = NULL;
    afterTriggers.events.tail = NULL;
    afterTriggers.events.tailfree = NULL;
  }

  /*
   * Forget any subtransaction state as well.  Since this can't be very
   * large, we let the eventual reset of TopTransactionContext free the
   * memory instead of doing it here.
   */
  afterTriggers.trans_stack = NULL;
  afterTriggers.maxtransdepth = 0;


  /*
   * Forget the query stack and constraint-related state information.  As
   * with the subtransaction state information, we don't bother freeing the
   * memory here.
   */
  afterTriggers.query_stack = NULL;
  afterTriggers.maxquerydepth = 0;
  afterTriggers.state = NULL;

  /* No more afterTriggers manipulation until next transaction starts. */
  afterTriggers.query_depth = -1;

  afterTriggers.firing_depth = 0;

  list_free_deep(afterTriggers.batch_callbacks);
  afterTriggers.batch_callbacks = NIL;
  afterTriggers.firing_batch_callbacks = false;
}

/*
 * AfterTriggerBeginSubXact()
 *
 *  Start a subtransaction.
 */
void
AfterTriggerBeginSubXact(void)
{
  int     my_level = GetCurrentTransactionNestLevel();

  /*
   * Allocate more space in the trans_stack if needed.  (Note: because the
   * minimum nest level of a subtransaction is 2, we waste the first couple
   * entries of the array; not worth the notational effort to avoid it.)
   */
  while (my_level >= afterTriggers.maxtransdepth)
  {
    if (afterTriggers.maxtransdepth == 0)
    {
      /* Arbitrarily initialize for max of 8 subtransaction levels */
      afterTriggers.trans_stack = (AfterTriggersTransData *)
        MemoryContextAlloc(TopTransactionContext,
                   8 * sizeof(AfterTriggersTransData));
      afterTriggers.maxtransdepth = 8;
    }
    else
    {
      /* repalloc will keep the stack in the same context */
      int     new_alloc = afterTriggers.maxtransdepth * 2;

      afterTriggers.trans_stack = (AfterTriggersTransData *)
        repalloc(afterTriggers.trans_stack,
             new_alloc * sizeof(AfterTriggersTransData));
      afterTriggers.maxtransdepth = new_alloc;
    }
  }

  /*
   * Push the current information into the stack.  The SET CONSTRAINTS state
   * is not saved until/unless changed.  Likewise, we don't make a
   * per-subtransaction event context until needed.
   */
  afterTriggers.trans_stack[my_level].state = NULL;
  afterTriggers.trans_stack[my_level].events = afterTriggers.events;
  afterTriggers.trans_stack[my_level].query_depth = afterTriggers.query_depth;
  afterTriggers.trans_stack[my_level].firing_counter = afterTriggers.firing_counter;
}

/*
 * AfterTriggerEndSubXact()
 *
 *  The current subtransaction is ending.
 */
void
AfterTriggerEndSubXact(bool isCommit)
{
  int     my_level = GetCurrentTransactionNestLevel();
  SetConstraintState state;
  AfterTriggerEvent event;
  AfterTriggerEventChunk *chunk;
  CommandId subxact_firing_id;

  /*
   * Pop the prior state if needed.
   */
  if (isCommit)
  {
    Assert(my_level < afterTriggers.maxtransdepth);
    /* If we saved a prior state, we don't need it anymore */
    state = afterTriggers.trans_stack[my_level].state;
    if (state != NULL)
      pfree(state);
    /* this avoids double pfree if error later: */
    afterTriggers.trans_stack[my_level].state = NULL;
    Assert(afterTriggers.query_depth ==
         afterTriggers.trans_stack[my_level].query_depth);
  }
  else
  {
    /*
     * Aborting.  It is possible subxact start failed before calling
     * AfterTriggerBeginSubXact, in which case we mustn't risk touching
     * trans_stack levels that aren't there.
     */
    if (my_level >= afterTriggers.maxtransdepth)
      return;

    /*
     * Release query-level storage for queries being aborted, and restore
     * query_depth to its pre-subxact value.  This assumes that a
     * subtransaction will not add events to query levels started in a
     * earlier transaction state.
     */
    while (afterTriggers.query_depth > afterTriggers.trans_stack[my_level].query_depth)
    {
      if (afterTriggers.query_depth < afterTriggers.maxquerydepth)
        AfterTriggerFreeQuery(&afterTriggers.query_stack[afterTriggers.query_depth]);
      afterTriggers.query_depth--;
    }
    Assert(afterTriggers.query_depth ==
         afterTriggers.trans_stack[my_level].query_depth);

    /*
     * Restore the global deferred-event list to its former length,
     * discarding any events queued by the subxact.
     */
    afterTriggerRestoreEventList(&afterTriggers.events,
                   &afterTriggers.trans_stack[my_level].events);

    /*
     * Restore the trigger state.  If the saved state is NULL, then this
     * subxact didn't save it, so it doesn't need restoring.
     */
    state = afterTriggers.trans_stack[my_level].state;
    if (state != NULL)
    {
      pfree(afterTriggers.state);
      afterTriggers.state = state;
    }
    /* this avoids double pfree if error later: */
    afterTriggers.trans_stack[my_level].state = NULL;

    /*
     * Scan for any remaining deferred events that were marked DONE or IN
     * PROGRESS by this subxact or a child, and un-mark them. We can
     * recognize such events because they have a firing ID greater than or
     * equal to the firing_counter value we saved at subtransaction start.
     * (This essentially assumes that the current subxact includes all
     * subxacts started after it.)
     */
    subxact_firing_id = afterTriggers.trans_stack[my_level].firing_counter;
    for_each_event_chunk(event, chunk, afterTriggers.events)
    {
      AfterTriggerShared evtshared = GetTriggerSharedData(event);

      if (event->ate_flags &
        (AFTER_TRIGGER_DONE | AFTER_TRIGGER_IN_PROGRESS))
      {
        if (evtshared->ats_firing_id >= subxact_firing_id)
          event->ate_flags &=
            ~(AFTER_TRIGGER_DONE | AFTER_TRIGGER_IN_PROGRESS);
      }
    }
  }

  /* Reset in case a callback threw an error while firing. */
  afterTriggers.firing_batch_callbacks = false;
}

/*
 * Get the transition table for the given event and depending on whether we are
 * processing the old or the new tuple.
 */
static Tuplestorestate *
GetAfterTriggersTransitionTable(int event,
                TupleTableSlot *oldslot,
                TupleTableSlot *newslot,
                TransitionCaptureState *transition_capture)
{
  Tuplestorestate *tuplestore = NULL;
  bool    delete_old_table = transition_capture->tcs_delete_old_table;
  bool    update_old_table = transition_capture->tcs_update_old_table;
  bool    update_new_table = transition_capture->tcs_update_new_table;
  bool    insert_new_table = transition_capture->tcs_insert_new_table;

  /*
   * For INSERT events NEW should be non-NULL, for DELETE events OLD should
   * be non-NULL, whereas for UPDATE events normally both OLD and NEW are
   * non-NULL.  But for UPDATE events fired for capturing transition tuples
   * during UPDATE partition-key row movement, OLD is NULL when the event is
   * for a row being inserted, whereas NEW is NULL when the event is for a
   * row being deleted.
   */
  Assert(!(event == TRIGGER_EVENT_DELETE && delete_old_table &&
       TupIsNull(oldslot)));
  Assert(!(event == TRIGGER_EVENT_INSERT && insert_new_table &&
       TupIsNull(newslot)));

  if (!TupIsNull(oldslot))
  {
    Assert(TupIsNull(newslot));
    if (event == TRIGGER_EVENT_DELETE && delete_old_table)
      tuplestore = transition_capture->tcs_delete_private->old_tuplestore;
    else if (event == TRIGGER_EVENT_UPDATE && update_old_table)
      tuplestore = transition_capture->tcs_update_private->old_tuplestore;
  }
  else if (!TupIsNull(newslot))
  {
    Assert(TupIsNull(oldslot));
    if (event == TRIGGER_EVENT_INSERT && insert_new_table)
      tuplestore = transition_capture->tcs_insert_private->new_tuplestore;
    else if (event == TRIGGER_EVENT_UPDATE && update_new_table)
      tuplestore = transition_capture->tcs_update_private->new_tuplestore;
  }

  return tuplestore;
}

/*
 * Add the given heap tuple to the given tuplestore, applying the conversion
 * map if necessary.
 *
 * If original_insert_tuple is given, we can add that tuple without conversion.
 */
static void
TransitionTableAddTuple(EState *estate,
            int event,
            TransitionCaptureState *transition_capture,
            ResultRelInfo *relinfo,
            TupleTableSlot *slot,
            TupleTableSlot *original_insert_tuple,
            Tuplestorestate *tuplestore)
{
  TupleConversionMap *map;

  /*
   * Nothing needs to be done if we don't have a tuplestore.
   */
  if (tuplestore == NULL)
    return;

  if (original_insert_tuple)
    tuplestore_puttupleslot(tuplestore, original_insert_tuple);
  else if ((map = ExecGetChildToRootMap(relinfo)) != NULL)
  {
    AfterTriggersTableData *table;
    TupleTableSlot *storeslot;

    switch (event)
    {
      case TRIGGER_EVENT_INSERT:
        table = transition_capture->tcs_insert_private;
        break;
      case TRIGGER_EVENT_UPDATE:
        table = transition_capture->tcs_update_private;
        break;
      case TRIGGER_EVENT_DELETE:
        table = transition_capture->tcs_delete_private;
        break;
      default:
        elog(ERROR, "invalid after-trigger event code: %d", event);
        table = NULL; /* keep compiler quiet */
        break;
    }

    storeslot = GetAfterTriggersStoreSlot(table, map->outdesc);
    execute_attr_map_slot(map->attrMap, slot, storeslot);
    tuplestore_puttupleslot(tuplestore, storeslot);
  }
  else
    tuplestore_puttupleslot(tuplestore, slot);
}

/* ----------
 * AfterTriggerEnlargeQueryState()
 *
 *  Prepare the necessary state so that we can record AFTER trigger events
 *  queued by a query.  It is allowed to have nested queries within a
 *  (sub)transaction, so we need to have separate state for each query
 *  nesting level.
 * ----------
 */
static void
AfterTriggerEnlargeQueryState(void)
{
  int     init_depth = afterTriggers.maxquerydepth;

  Assert(afterTriggers.query_depth >= afterTriggers.maxquerydepth);

  if (afterTriggers.maxquerydepth == 0)
  {
    int     new_alloc = Max(afterTriggers.query_depth + 1, 8);

    afterTriggers.query_stack = (AfterTriggersQueryData *)
      MemoryContextAlloc(TopTransactionContext,
                 new_alloc * sizeof(AfterTriggersQueryData));
    afterTriggers.maxquerydepth = new_alloc;
  }
  else
  {
    /* repalloc will keep the stack in the same context */
    int     old_alloc = afterTriggers.maxquerydepth;
    int     new_alloc = Max(afterTriggers.query_depth + 1,
                  old_alloc * 2);

    afterTriggers.query_stack = (AfterTriggersQueryData *)
      repalloc(afterTriggers.query_stack,
           new_alloc * sizeof(AfterTriggersQueryData));
    afterTriggers.maxquerydepth = new_alloc;
  }

  /* Initialize new array entries to empty */
  while (init_depth < afterTriggers.maxquerydepth)
  {
    AfterTriggersQueryData *qs = &afterTriggers.query_stack[init_depth];

    qs->events.head = NULL;
    qs->events.tail = NULL;
    qs->events.tailfree = NULL;
    qs->fdw_tuplestore = NULL;
    qs->tables = NIL;
    qs->batch_callbacks = NIL;

    ++init_depth;
  }
}

/*
 * Create an empty SetConstraintState with room for numalloc trigstates
 */
static SetConstraintState
SetConstraintStateCreate(int numalloc)
{
  SetConstraintState state;

  /* Behave sanely with numalloc == 0 */
  if (numalloc <= 0)
    numalloc = 1;

  /*
   * We assume that zeroing will correctly initialize the state values.
   */
  state = (SetConstraintState)
    MemoryContextAllocZero(TopTransactionContext,
                 offsetof(SetConstraintStateData, trigstates) +
                 numalloc * sizeof(SetConstraintTriggerData));

  state->numalloc = numalloc;

  return state;
}

/*
 * Copy a SetConstraintState
 */
static SetConstraintState
SetConstraintStateCopy(SetConstraintState origstate)
{
  SetConstraintState state;

  state = SetConstraintStateCreate(origstate->numstates);

  state->all_isset = origstate->all_isset;
  state->all_isdeferred = origstate->all_isdeferred;
  state->numstates = origstate->numstates;
  memcpy(state->trigstates, origstate->trigstates,
       origstate->numstates * sizeof(SetConstraintTriggerData));

  return state;
}

/*
 * Add a per-trigger item to a SetConstraintState.  Returns possibly-changed
 * pointer to the state object (it will change if we have to repalloc).
 */
static SetConstraintState
SetConstraintStateAddItem(SetConstraintState state,
              Oid tgoid, bool tgisdeferred)
{
  if (state->numstates >= state->numalloc)
  {
    int     newalloc = state->numalloc * 2;

    newalloc = Max(newalloc, 8);  /* in case original has size 0 */
    state = (SetConstraintState)
      repalloc(state,
           offsetof(SetConstraintStateData, trigstates) +
           newalloc * sizeof(SetConstraintTriggerData));
    state->numalloc = newalloc;
    Assert(state->numstates < state->numalloc);
  }

  state->trigstates[state->numstates].sct_tgoid = tgoid;
  state->trigstates[state->numstates].sct_tgisdeferred = tgisdeferred;
  state->numstates++;

  return state;
}

/* ----------
 * AfterTriggerSetState()
 *
 *  Execute the SET CONSTRAINTS ... utility command.
 * ----------
 */
void
AfterTriggerSetState(ConstraintsSetStmt *stmt)
{
  int     my_level = GetCurrentTransactionNestLevel();

  /* If we haven't already done so, initialize our state. */
  if (afterTriggers.state == NULL)
    afterTriggers.state = SetConstraintStateCreate(8);

  /*
   * If in a subtransaction, and we didn't save the current state already,
   * save it so it can be restored if the subtransaction aborts.
   */
  if (my_level > 1 &&
    afterTriggers.trans_stack[my_level].state == NULL)
  {
    afterTriggers.trans_stack[my_level].state =
      SetConstraintStateCopy(afterTriggers.state);
  }

  /*
   * Handle SET CONSTRAINTS ALL ...
   */
  if (stmt->constraints == NIL)
  {
    /*
     * Forget any previous SET CONSTRAINTS commands in this transaction.
     */
    afterTriggers.state->numstates = 0;

    /*
     * Set the per-transaction ALL state to known.
     */
    afterTriggers.state->all_isset = true;
    afterTriggers.state->all_isdeferred = stmt->deferred;
  }
  else
  {
    Relation  conrel;
    Relation  tgrel;
    List     *conoidlist = NIL;
    List     *tgoidlist = NIL;
    ListCell   *lc;

    /*
     * Handle SET CONSTRAINTS constraint-name [, ...]
     *
     * First, identify all the named constraints and make a list of their
     * OIDs.  Since, unlike the SQL spec, we allow multiple constraints of
     * the same name within a schema, the specifications are not
     * necessarily unique.  Our strategy is to target all matching
     * constraints within the first search-path schema that has any
     * matches, but disregard matches in schemas beyond the first match.
     * (This is a bit odd but it's the historical behavior.)
     *
     * A constraint in a partitioned table may have corresponding
     * constraints in the partitions.  Grab those too.
     */
    conrel = table_open(ConstraintRelationId, AccessShareLock);

    foreach(lc, stmt->constraints)
    {
      RangeVar   *constraint = lfirst(lc);
      bool    found;
      List     *namespacelist;
      ListCell   *nslc;

      if (constraint->catalogname)
      {
        if (strcmp(constraint->catalogname, get_database_name(MyDatabaseId)) != 0)
          ereport(ERROR,
              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
               errmsg("cross-database references are not implemented: \"%s.%s.%s\"",
                  constraint->catalogname, constraint->schemaname,
                  constraint->relname)));
      }

      /*
       * If we're given the schema name with the constraint, look only
       * in that schema.  If given a bare constraint name, use the
       * search path to find the first matching constraint.
       */
      if (constraint->schemaname)
      {
        Oid     namespaceId = LookupExplicitNamespace(constraint->schemaname,
                                  false);

        namespacelist = list_make1_oid(namespaceId);
      }
      else
      {
        namespacelist = fetch_search_path(true);
      }

      found = false;
      foreach(nslc, namespacelist)
      {
        Oid     namespaceId = lfirst_oid(nslc);
        SysScanDesc conscan;
        ScanKeyData skey[2];
        HeapTuple tup;

        ScanKeyInit(&skey[0],
              Anum_pg_constraint_conname,
              BTEqualStrategyNumber, F_NAMEEQ,
              CStringGetDatum(constraint->relname));
        ScanKeyInit(&skey[1],
              Anum_pg_constraint_connamespace,
              BTEqualStrategyNumber, F_OIDEQ,
              ObjectIdGetDatum(namespaceId));

        conscan = systable_beginscan(conrel, ConstraintNameNspIndexId,
                       true, NULL, 2, skey);

        while (HeapTupleIsValid(tup = systable_getnext(conscan)))
        {
          Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tup);

          if (con->condeferrable)
            conoidlist = lappend_oid(conoidlist, con->oid);
          else if (stmt->deferred)
            ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("constraint \"%s\" is not deferrable",
                    constraint->relname)));
          found = true;
        }

        systable_endscan(conscan);

        /*
         * Once we've found a matching constraint we do not search
         * later parts of the search path.
         */
        if (found)
          break;
      }

      list_free(namespacelist);

      /*
       * Not found ?
       */
      if (!found)
        ereport(ERROR,
            (errcode(ERRCODE_UNDEFINED_OBJECT),
             errmsg("constraint \"%s\" does not exist",
                constraint->relname)));
    }

    /*
     * Scan for any possible descendants of the constraints.  We append
     * whatever we find to the same list that we're scanning; this has the
     * effect that we create new scans for those, too, so if there are
     * further descendents, we'll also catch them.
     */
    foreach(lc, conoidlist)
    {
      Oid     parent = lfirst_oid(lc);
      ScanKeyData key;
      SysScanDesc scan;
      HeapTuple tuple;

      ScanKeyInit(&key,
            Anum_pg_constraint_conparentid,
            BTEqualStrategyNumber, F_OIDEQ,
            ObjectIdGetDatum(parent));

      scan = systable_beginscan(conrel, ConstraintParentIndexId, true, NULL, 1, &key);

      while (HeapTupleIsValid(tuple = systable_getnext(scan)))
      {
        Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);

        conoidlist = lappend_oid(conoidlist, con->oid);
      }

      systable_endscan(scan);
    }

    table_close(conrel, AccessShareLock);

    /*
     * Now, locate the trigger(s) implementing each of these constraints,
     * and make a list of their OIDs.
     */
    tgrel = table_open(TriggerRelationId, AccessShareLock);

    foreach(lc, conoidlist)
    {
      Oid     conoid = lfirst_oid(lc);
      ScanKeyData skey;
      SysScanDesc tgscan;
      HeapTuple htup;

      ScanKeyInit(&skey,
            Anum_pg_trigger_tgconstraint,
            BTEqualStrategyNumber, F_OIDEQ,
            ObjectIdGetDatum(conoid));

      tgscan = systable_beginscan(tgrel, TriggerConstraintIndexId, true,
                    NULL, 1, &skey);

      while (HeapTupleIsValid(htup = systable_getnext(tgscan)))
      {
        Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(htup);

        /*
         * Silently skip triggers that are marked as non-deferrable in
         * pg_trigger.  This is not an error condition, since a
         * deferrable RI constraint may have some non-deferrable
         * actions.
         */
        if (pg_trigger->tgdeferrable)
          tgoidlist = lappend_oid(tgoidlist, pg_trigger->oid);
      }

      systable_endscan(tgscan);
    }

    table_close(tgrel, AccessShareLock);

    /*
     * Now we can set the trigger states of individual triggers for this
     * xact.
     */
    foreach(lc, tgoidlist)
    {
      Oid     tgoid = lfirst_oid(lc);
      SetConstraintState state = afterTriggers.state;
      bool    found = false;
      int     i;

      for (i = 0; i < state->numstates; i++)
      {
        if (state->trigstates[i].sct_tgoid == tgoid)
        {
          state->trigstates[i].sct_tgisdeferred = stmt->deferred;
          found = true;
          break;
        }
      }
      if (!found)
      {
        afterTriggers.state =
          SetConstraintStateAddItem(state, tgoid, stmt->deferred);
      }
    }
  }

  /*
   * SQL99 requires that when a constraint is set to IMMEDIATE, any deferred
   * checks against that constraint must be made when the SET CONSTRAINTS
   * command is executed -- i.e. the effects of the SET CONSTRAINTS command
   * apply retroactively.  We've updated the constraints state, so scan the
   * list of previously deferred events to fire any that have now become
   * immediate.
   *
   * Obviously, if this was SET ... DEFERRED then it can't have converted
   * any unfired events to immediate, so we need do nothing in that case.
   */
  if (!stmt->deferred)
  {
    AfterTriggerEventList *events = &afterTriggers.events;
    bool    snapshot_set = false;

    afterTriggers.firing_depth++;
    while (afterTriggerMarkEvents(events, NULL, true))
    {
      CommandId firing_id = afterTriggers.firing_counter++;

      /*
       * Make sure a snapshot has been established in case trigger
       * functions need one.  Note that we avoid setting a snapshot if
       * we don't find at least one trigger that has to be fired now.
       * This is so that BEGIN; SET CONSTRAINTS ...; SET TRANSACTION
       * ISOLATION LEVEL SERIALIZABLE; ... works properly.  (If we are
       * at the start of a transaction it's not possible for any trigger
       * events to be queued yet.)
       */
      if (!snapshot_set)
      {
        PushActiveSnapshot(GetTransactionSnapshot());
        snapshot_set = true;
      }

      /*
       * We can delete fired events if we are at top transaction level,
       * but we'd better not if inside a subtransaction, since the
       * subtransaction could later get rolled back.
       */
      if (afterTriggerInvokeEvents(events, firing_id, NULL,
                     !IsSubTransaction()))
        break;     /* all fired */
    }

    /*
     * Flush any fast-path batches accumulated by the triggers just fired.
     */
    FireAfterTriggerBatchCallbacks(afterTriggers.batch_callbacks);
    afterTriggers.firing_depth--;
    list_free_deep(afterTriggers.batch_callbacks);
    afterTriggers.batch_callbacks = NIL;

    if (snapshot_set)
      PopActiveSnapshot();
  }
}

/* ----------
 * AfterTriggerPendingOnRel()
 *    Test to see if there are any pending after-trigger events for rel.
 *
 * This is used by TRUNCATE, CLUSTER, ALTER TABLE, etc to detect whether
 * it is unsafe to perform major surgery on a relation.  Note that only
 * local pending events are examined.  We assume that having exclusive lock
 * on a rel guarantees there are no unserviced events in other backends ---
 * but having a lock does not prevent there being such events in our own.
 *
 * In some scenarios it'd be reasonable to remove pending events (more
 * specifically, mark them DONE by the current subxact) but without a lot
 * of knowledge of the trigger semantics we can't do this in general.
 * ----------
 */
bool
AfterTriggerPendingOnRel(Oid relid)
{
  AfterTriggerEvent event;
  AfterTriggerEventChunk *chunk;
  int     depth;

  /* Scan queued events */
  for_each_event_chunk(event, chunk, afterTriggers.events)
  {
    AfterTriggerShared evtshared = GetTriggerSharedData(event);

    /*
     * We can ignore completed events.  (Even if a DONE flag is rolled
     * back by subxact abort, it's OK because the effects of the TRUNCATE
     * or whatever must get rolled back too.)
     */
    if (event->ate_flags & AFTER_TRIGGER_DONE)
      continue;

    if (evtshared->ats_relid == relid)
      return true;
  }

  /*
   * Also scan events queued by incomplete queries.  This could only matter
   * if TRUNCATE/etc is executed by a function or trigger within an updating
   * query on the same relation, which is pretty perverse, but let's check.
   */
  for (depth = 0; depth <= afterTriggers.query_depth && depth < afterTriggers.maxquerydepth; depth++)
  {
    for_each_event_chunk(event, chunk, afterTriggers.query_stack[depth].events)
    {
      AfterTriggerShared evtshared = GetTriggerSharedData(event);

      if (event->ate_flags & AFTER_TRIGGER_DONE)
        continue;

      if (evtshared->ats_relid == relid)
        return true;
    }
  }

  return false;
}

/* ----------
 * AfterTriggerSaveEvent()
 *
 *  Called by ExecA[RS]...Triggers() to queue up the triggers that should
 *  be fired for an event.
 *
 *  NOTE: this is called whenever there are any triggers associated with
 *  the event (even if they are disabled).  This function decides which
 *  triggers actually need to be queued.  It is also called after each row,
 *  even if there are no triggers for that event, if there are any AFTER
 *  STATEMENT triggers for the statement which use transition tables, so that
 *  the transition tuplestores can be built.  Furthermore, if the transition
 *  capture is happening for UPDATEd rows being moved to another partition due
 *  to the partition-key being changed, then this function is called once when
 *  the row is deleted (to capture OLD row), and once when the row is inserted
 *  into another partition (to capture NEW row).  This is done separately because
 *  DELETE and INSERT happen on different tables.
 *
 *  Transition tuplestores are built now, rather than when events are pulled
 *  off of the queue because AFTER ROW triggers are allowed to select from the
 *  transition tables for the statement.
 *
 *  This contains special support to queue the update events for the case where
 *  a partitioned table undergoing a cross-partition update may have foreign
 *  keys pointing into it.  Normally, a partitioned table's row triggers are
 *  not fired because the leaf partition(s) which are modified as a result of
 *  the operation on the partitioned table contain the same triggers which are
 *  fired instead. But that general scheme can cause problematic behavior with
 *  foreign key triggers during cross-partition updates, which are implemented
 *  as DELETE on the source partition followed by INSERT into the destination
 *  partition.  Specifically, firing DELETE triggers would lead to the wrong
 *  foreign key action to be enforced considering that the original command is
 *  UPDATE; in this case, this function is called with relinfo as the
 *  partitioned table, and src_partinfo and dst_partinfo referring to the
 *  source and target leaf partitions, respectively.
 *
 *  is_crosspart_update is true either when a DELETE event is fired on the
 *  source partition (which is to be ignored) or an UPDATE event is fired on
 *  the root partitioned table.
 * ----------
 */
static void
AfterTriggerSaveEvent(EState *estate, ResultRelInfo *relinfo,
            ResultRelInfo *src_partinfo,
            ResultRelInfo *dst_partinfo,
            int event, bool row_trigger,
            TupleTableSlot *oldslot, TupleTableSlot *newslot,
            List *recheckIndexes, Bitmapset *modifiedCols,
            TransitionCaptureState *transition_capture,
            bool is_crosspart_update)
{
  Relation  rel = relinfo->ri_RelationDesc;
  TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
  AfterTriggerEventData new_event;
  AfterTriggerSharedData new_shared;
  char    relkind = rel->rd_rel->relkind;
  int     tgtype_event;
  int     tgtype_level;
  int     i;
  Tuplestorestate *fdw_tuplestore = NULL;

  /*
   * Check state.  We use a normal test not Assert because it is possible to
   * reach here in the wrong state given misconfigured RI triggers, in
   * particular deferring a cascade action trigger.
   */
  if (afterTriggers.query_depth < 0)
    elog(ERROR, "AfterTriggerSaveEvent() called outside of query");

  /* Be sure we have enough space to record events at this query depth. */
  if (afterTriggers.query_depth >= afterTriggers.maxquerydepth)
    AfterTriggerEnlargeQueryState();

  /*
   * If the directly named relation has any triggers with transition tables,
   * then we need to capture transition tuples.
   */
  if (row_trigger && transition_capture != NULL)
  {
    TupleTableSlot *original_insert_tuple = transition_capture->tcs_original_insert_tuple;

    /*
     * Capture the old tuple in the appropriate transition table based on
     * the event.
     */
    if (!TupIsNull(oldslot))
    {
      Tuplestorestate *old_tuplestore;

      old_tuplestore = GetAfterTriggersTransitionTable(event,
                               oldslot,
                               NULL,
                               transition_capture);
      TransitionTableAddTuple(estate, event, transition_capture, relinfo,
                  oldslot, NULL, old_tuplestore);
    }

    /*
     * Capture the new tuple in the appropriate transition table based on
     * the event.
     */
    if (!TupIsNull(newslot))
    {
      Tuplestorestate *new_tuplestore;

      new_tuplestore = GetAfterTriggersTransitionTable(event,
                               NULL,
                               newslot,
                               transition_capture);
      TransitionTableAddTuple(estate, event, transition_capture, relinfo,
                  newslot, original_insert_tuple, new_tuplestore);
    }

    /*
     * If transition tables are the only reason we're here, return. As
     * mentioned above, we can also be here during update tuple routing in
     * presence of transition tables, in which case this function is
     * called separately for OLD and NEW, so we expect exactly one of them
     * to be NULL.
     */
    if (trigdesc == NULL ||
      (event == TRIGGER_EVENT_DELETE && !trigdesc->trig_delete_after_row) ||
      (event == TRIGGER_EVENT_INSERT && !trigdesc->trig_insert_after_row) ||
      (event == TRIGGER_EVENT_UPDATE && !trigdesc->trig_update_after_row) ||
      (event == TRIGGER_EVENT_UPDATE && (TupIsNull(oldslot) ^ TupIsNull(newslot))))
      return;
  }

  /*
   * We normally don't see partitioned tables here for row level triggers
   * except in the special case of a cross-partition update.  In that case,
   * nodeModifyTable.c:ExecCrossPartitionUpdateForeignKey() calls here to
   * queue an update event on the root target partitioned table, also
   * passing the source and destination partitions and their tuples.
   */
  Assert(!row_trigger ||
       rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE ||
       (is_crosspart_update &&
      TRIGGER_FIRED_BY_UPDATE(event) &&
      src_partinfo != NULL && dst_partinfo != NULL));

  /*
   * Validate the event code and collect the associated tuple CTIDs.
   *
   * The event code will be used both as a bitmask and an array offset, so
   * validation is important to make sure we don't walk off the edge of our
   * arrays.
   *
   * Also, if we're considering statement-level triggers, check whether we
   * already queued a set of them for this event, and cancel the prior set
   * if so.  This preserves the behavior that statement-level triggers fire
   * just once per statement and fire after row-level triggers.
   */
  switch (event)
  {
    case TRIGGER_EVENT_INSERT:
      tgtype_event = TRIGGER_TYPE_INSERT;
      if (row_trigger)
      {
        Assert(oldslot == NULL);
        Assert(newslot != NULL);
        ItemPointerCopy(&(newslot->tts_tid), &(new_event.ate_ctid1));
        ItemPointerSetInvalid(&(new_event.ate_ctid2));
      }
      else
      {
        Assert(oldslot == NULL);
        Assert(newslot == NULL);
        ItemPointerSetInvalid(&(new_event.ate_ctid1));
        ItemPointerSetInvalid(&(new_event.ate_ctid2));
        cancel_prior_stmt_triggers(RelationGetRelid(rel),
                       CMD_INSERT, event);
      }
      break;
    case TRIGGER_EVENT_DELETE:
      tgtype_event = TRIGGER_TYPE_DELETE;
      if (row_trigger)
      {
        Assert(oldslot != NULL);
        Assert(newslot == NULL);
        ItemPointerCopy(&(oldslot->tts_tid), &(new_event.ate_ctid1));
        ItemPointerSetInvalid(&(new_event.ate_ctid2));
      }
      else
      {
        Assert(oldslot == NULL);
        Assert(newslot == NULL);
        ItemPointerSetInvalid(&(new_event.ate_ctid1));
        ItemPointerSetInvalid(&(new_event.ate_ctid2));
        cancel_prior_stmt_triggers(RelationGetRelid(rel),
                       CMD_DELETE, event);
      }
      break;
    case TRIGGER_EVENT_UPDATE:
      tgtype_event = TRIGGER_TYPE_UPDATE;
      if (row_trigger)
      {
        Assert(oldslot != NULL);
        Assert(newslot != NULL);
        ItemPointerCopy(&(oldslot->tts_tid), &(new_event.ate_ctid1));
        ItemPointerCopy(&(newslot->tts_tid), &(new_event.ate_ctid2));

        /*
         * Also remember the OIDs of partitions to fetch these tuples
         * out of later in AfterTriggerExecute().
         */
        if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
        {
          Assert(src_partinfo != NULL && dst_partinfo != NULL);
          new_event.ate_src_part =
            RelationGetRelid(src_partinfo->ri_RelationDesc);
          new_event.ate_dst_part =
            RelationGetRelid(dst_partinfo->ri_RelationDesc);
        }
      }
      else
      {
        Assert(oldslot == NULL);
        Assert(newslot == NULL);
        ItemPointerSetInvalid(&(new_event.ate_ctid1));
        ItemPointerSetInvalid(&(new_event.ate_ctid2));
        cancel_prior_stmt_triggers(RelationGetRelid(rel),
                       CMD_UPDATE, event);
      }
      break;
    case TRIGGER_EVENT_TRUNCATE:
      tgtype_event = TRIGGER_TYPE_TRUNCATE;
      Assert(oldslot == NULL);
      Assert(newslot == NULL);
      ItemPointerSetInvalid(&(new_event.ate_ctid1));
      ItemPointerSetInvalid(&(new_event.ate_ctid2));
      break;
    default:
      elog(ERROR, "invalid after-trigger event code: %d", event);
      tgtype_event = 0; /* keep compiler quiet */
      break;
  }

  /* Determine flags */
  if (!(relkind == RELKIND_FOREIGN_TABLE && row_trigger))
  {
    if (row_trigger && event == TRIGGER_EVENT_UPDATE)
    {
      if (relkind == RELKIND_PARTITIONED_TABLE)
        new_event.ate_flags = AFTER_TRIGGER_CP_UPDATE;
      else
        new_event.ate_flags = AFTER_TRIGGER_2CTID;
    }
    else
      new_event.ate_flags = AFTER_TRIGGER_1CTID;
  }

  /* else, we'll initialize ate_flags for each trigger */

  tgtype_level = (row_trigger ? TRIGGER_TYPE_ROW : TRIGGER_TYPE_STATEMENT);

  /*
   * Must convert/copy the source and destination partition tuples into the
   * root partitioned table's format/slot, because the processing in the
   * loop below expects both oldslot and newslot tuples to be in that form.
   */
  if (row_trigger && rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
  {
    TupleTableSlot *rootslot;
    TupleConversionMap *map;

    rootslot = ExecGetTriggerOldSlot(estate, relinfo);
    map = ExecGetChildToRootMap(src_partinfo);
    if (map)
      oldslot = execute_attr_map_slot(map->attrMap,
                      oldslot,
                      rootslot);
    else
      oldslot = ExecCopySlot(rootslot, oldslot);

    rootslot = ExecGetTriggerNewSlot(estate, relinfo);
    map = ExecGetChildToRootMap(dst_partinfo);
    if (map)
      newslot = execute_attr_map_slot(map->attrMap,
                      newslot,
                      rootslot);
    else
      newslot = ExecCopySlot(rootslot, newslot);
  }

  for (i = 0; i < trigdesc->numtriggers; i++)
  {
    Trigger    *trigger = &trigdesc->triggers[i];

    if (!TRIGGER_TYPE_MATCHES(trigger->tgtype,
                  tgtype_level,
                  TRIGGER_TYPE_AFTER,
                  tgtype_event))
      continue;
    if (!TriggerEnabled(estate, relinfo, trigger, event,
              modifiedCols, oldslot, newslot))
      continue;

    if (relkind == RELKIND_FOREIGN_TABLE && row_trigger)
    {
      if (fdw_tuplestore == NULL)
      {
        fdw_tuplestore = GetCurrentFDWTuplestore();
        new_event.ate_flags = AFTER_TRIGGER_FDW_FETCH;
      }
      else
        /* subsequent event for the same tuple */
        new_event.ate_flags = AFTER_TRIGGER_FDW_REUSE;
    }

    /*
     * If the trigger is a foreign key enforcement trigger, there are
     * certain cases where we can skip queueing the event because we can
     * tell by inspection that the FK constraint will still pass. There
     * are also some cases during cross-partition updates of a partitioned
     * table where queuing the event can be skipped.
     */
    if (TRIGGER_FIRED_BY_UPDATE(event) || TRIGGER_FIRED_BY_DELETE(event))
    {
      switch (RI_FKey_trigger_type(trigger->tgfoid))
      {
        case RI_TRIGGER_PK:

          /*
           * For cross-partitioned updates of partitioned PK table,
           * skip the event fired by the component delete on the
           * source leaf partition unless the constraint originates
           * in the partition itself (!tgisclone), because the
           * update event that will be fired on the root
           * (partitioned) target table will be used to perform the
           * necessary foreign key enforcement action.
           */
          if (is_crosspart_update &&
            TRIGGER_FIRED_BY_DELETE(event) &&
            trigger->tgisclone)
            continue;

          /* Update or delete on trigger's PK table */
          if (!RI_FKey_pk_upd_check_required(trigger, rel,
                             oldslot, newslot))
          {
            /* skip queuing this event */
            continue;
          }
          break;

        case RI_TRIGGER_FK:

          /*
           * Update on trigger's FK table.  We can skip the update
           * event fired on a partitioned table during a
           * cross-partition of that table, because the insert event
           * that is fired on the destination leaf partition would
           * suffice to perform the necessary foreign key check.
           * Moreover, RI_FKey_fk_upd_check_required() expects to be
           * passed a tuple that contains system attributes, most of
           * which are not present in the virtual slot belonging to
           * a partitioned table.
           */
          if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ||
            !RI_FKey_fk_upd_check_required(trigger, rel,
                             oldslot, newslot))
          {
            /* skip queuing this event */
            continue;
          }
          break;

        case RI_TRIGGER_NONE:

          /*
           * Not an FK trigger.  No need to queue the update event
           * fired during a cross-partitioned update of a
           * partitioned table, because the same row trigger must be
           * present in the leaf partition(s) that are affected as
           * part of this update and the events fired on them are
           * queued instead.
           */
          if (row_trigger &&
            rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
            continue;
          break;
      }
    }

    /*
     * If the trigger is a deferred unique constraint check trigger, only
     * queue it if the unique constraint was potentially violated, which
     * we know from index insertion time.
     */
    if (trigger->tgfoid == F_UNIQUE_KEY_RECHECK)
    {
      if (!list_member_oid(recheckIndexes, trigger->tgconstrindid))
        continue;   /* Uniqueness definitely not violated */
    }

    /*
     * Fill in event structure and add it to the current query's queue.
     * Note we set ats_table to NULL whenever this trigger doesn't use
     * transition tables, to improve sharability of the shared event data.
     */
    new_shared.ats_event =
      (event & TRIGGER_EVENT_OPMASK) |
      (row_trigger ? TRIGGER_EVENT_ROW : 0) |
      (trigger->tgdeferrable ? AFTER_TRIGGER_DEFERRABLE : 0) |
      (trigger->tginitdeferred ? AFTER_TRIGGER_INITDEFERRED : 0);
    new_shared.ats_tgoid = trigger->tgoid;
    new_shared.ats_relid = RelationGetRelid(rel);
    new_shared.ats_rolid = GetUserId();
    new_shared.ats_firing_id = 0;
    if ((trigger->tgoldtable || trigger->tgnewtable) &&
      transition_capture != NULL)
    {
      switch (event)
      {
        case TRIGGER_EVENT_INSERT:
          new_shared.ats_table = transition_capture->tcs_insert_private;
          break;
        case TRIGGER_EVENT_UPDATE:
          new_shared.ats_table = transition_capture->tcs_update_private;
          break;
        case TRIGGER_EVENT_DELETE:
          new_shared.ats_table = transition_capture->tcs_delete_private;
          break;
        default:
          /* Must be TRUNCATE, see switch above */
          new_shared.ats_table = NULL;
          break;
      }
    }
    else
      new_shared.ats_table = NULL;
    new_shared.ats_modifiedcols = modifiedCols;

    afterTriggerAddEvent(&afterTriggers.query_stack[afterTriggers.query_depth].events,
               &new_event, &new_shared);
  }

  /*
   * Finally, spool any foreign tuple(s).  The tuplestore squashes them to
   * minimal tuples, so this loses any system columns.  The executor lost
   * those columns before us, for an unrelated reason, so this is fine.
   */
  if (fdw_tuplestore)
  {
    if (oldslot != NULL)
      tuplestore_puttupleslot(fdw_tuplestore, oldslot);
    if (newslot != NULL)
      tuplestore_puttupleslot(fdw_tuplestore, newslot);
  }
}

/*
 * Detect whether we already queued BEFORE STATEMENT triggers for the given
 * relation + operation, and set the flag so the next call will report "true".
 */
static bool
before_stmt_triggers_fired(Oid relid, CmdType cmdType)
{
  bool    result;
  AfterTriggersTableData *table;

  /* Check state, like AfterTriggerSaveEvent. */
  if (afterTriggers.query_depth < 0)
    elog(ERROR, "before_stmt_triggers_fired() called outside of query");

  /* Be sure we have enough space to record events at this query depth. */
  if (afterTriggers.query_depth >= afterTriggers.maxquerydepth)
    AfterTriggerEnlargeQueryState();

  /*
   * We keep this state in the AfterTriggersTableData that also holds
   * transition tables for the relation + operation.  In this way, if we are
   * forced to make a new set of transition tables because more tuples get
   * entered after we've already fired triggers, we will allow a new set of
   * statement triggers to get queued.
   */
  table = GetAfterTriggersTableData(relid, cmdType);
  result = table->before_trig_done;
  table->before_trig_done = true;
  return result;
}

/*
 * If we previously queued a set of AFTER STATEMENT triggers for the given
 * relation + operation, and they've not been fired yet, cancel them.  The
 * caller will queue a fresh set that's after any row-level triggers that may
 * have been queued by the current sub-statement, preserving (as much as
 * possible) the property that AFTER ROW triggers fire before AFTER STATEMENT
 * triggers, and that the latter only fire once.  This deals with the
 * situation where several FK enforcement triggers sequentially queue triggers
 * for the same table into the same trigger query level.  We can't fully
 * prevent odd behavior though: if there are AFTER ROW triggers taking
 * transition tables, we don't want to change the transition tables once the
 * first such trigger has seen them.  In such a case, any additional events
 * will result in creating new transition tables and allowing new firings of
 * statement triggers.
 *
 * This also saves the current event list location so that a later invocation
 * of this function can cheaply find the triggers we're about to queue and
 * cancel them.
 */
static void
cancel_prior_stmt_triggers(Oid relid, CmdType cmdType, int tgevent)
{
  AfterTriggersTableData *table;
  AfterTriggersQueryData *qs = &afterTriggers.query_stack[afterTriggers.query_depth];

  /*
   * We keep this state in the AfterTriggersTableData that also holds
   * transition tables for the relation + operation.  In this way, if we are
   * forced to make a new set of transition tables because more tuples get
   * entered after we've already fired triggers, we will allow a new set of
   * statement triggers to get queued without canceling the old ones.
   */
  table = GetAfterTriggersTableData(relid, cmdType);

  if (table->after_trig_done)
  {
    /*
     * We want to start scanning from the tail location that existed just
     * before we inserted any statement triggers.  But the events list
     * might've been entirely empty then, in which case scan from the
     * current head.
     */
    AfterTriggerEvent event;
    AfterTriggerEventChunk *chunk;

    if (table->after_trig_events.tail)
    {
      chunk = table->after_trig_events.tail;
      event = (AfterTriggerEvent) table->after_trig_events.tailfree;
    }
    else
    {
      chunk = qs->events.head;
      event = NULL;
    }

    for_each_chunk_from(chunk)
    {
      if (event == NULL)
        event = (AfterTriggerEvent) CHUNK_DATA_START(chunk);
      for_each_event_from(event, chunk)
      {
        AfterTriggerShared evtshared = GetTriggerSharedData(event);

        /*
         * Exit loop when we reach events that aren't AS triggers for
         * the target relation.
         */
        if (evtshared->ats_relid != relid)
          goto done;
        if ((evtshared->ats_event & TRIGGER_EVENT_OPMASK) != tgevent)
          goto done;
        if (!TRIGGER_FIRED_FOR_STATEMENT(evtshared->ats_event))
          goto done;
        if (!TRIGGER_FIRED_AFTER(evtshared->ats_event))
          goto done;
        /* OK, mark it DONE */
        event->ate_flags &= ~AFTER_TRIGGER_IN_PROGRESS;
        event->ate_flags |= AFTER_TRIGGER_DONE;
      }
      /* signal we must reinitialize event ptr for next chunk */
      event = NULL;
    }
  }
done:

  /* In any case, save current insertion point for next time */
  table->after_trig_done = true;
  table->after_trig_events = qs->events;
}

/*
 * GUC assign_hook for session_replication_role
 */
void
assign_session_replication_role(int newval, void *extra)
{
  /*
   * Must flush the plan cache when changing replication role; but don't
   * flush unnecessarily.
   */
  if (SessionReplicationRole != newval)
    ResetPlanCache();
}

/*
 * SQL function pg_trigger_depth()
 */
Datum
pg_trigger_depth(PG_FUNCTION_ARGS)
{
  PG_RETURN_INT32(MyTriggerDepth);
}

/*
 * Check whether a trigger modified a virtual generated column and replace the
 * value with null if so.
 *
 * We need to check this so that we don't end up storing a non-null value in a
 * virtual generated column.
 *
 * We don't need to check for stored generated columns, since those will be
 * overwritten later anyway.
 */
static HeapTuple
check_modified_virtual_generated(TupleDesc tupdesc, HeapTuple tuple)
{
  if (!(tupdesc->constr && tupdesc->constr->has_generated_virtual))
    return tuple;

  for (int i = 0; i < tupdesc->natts; i++)
  {
    if (TupleDescAttr(tupdesc, i)->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
    {
      if (!heap_attisnull(tuple, i + 1, tupdesc))
      {
        int     replCol = i + 1;
        Datum   replValue = 0;
        bool    replIsnull = true;

        tuple = heap_modify_tuple_by_cols(tuple, tupdesc, 1, &replCol, &replValue, &replIsnull);
      }
    }
  }

  return tuple;
}

/*
 * RegisterAfterTriggerBatchCallback
 *    Register a function to be called when the current trigger-firing
 *    batch completes.
 *
 * Must be called from within a trigger function's execution context
 * (i.e., while afterTriggers state is active).
 *
 * The callback list is cleared after invocation, so the caller must
 * re-register for each new batch if needed.
 */
void
RegisterAfterTriggerBatchCallback(AfterTriggerBatchCallback callback,
                  void *arg)
{
  AfterTriggerCallbackItem *item;
  MemoryContext oldcxt;

  /*
   * Allocate in TopTransactionContext so the item survives for the duration
   * of the batch, which may span multiple trigger invocations.
   *
   * Must be called while afterTriggers is active; callbacks registered
   * outside a trigger-firing context would never fire.
   */
  Assert(afterTriggers.firing_depth > 0);
  Assert(!afterTriggers.firing_batch_callbacks);
  oldcxt = MemoryContextSwitchTo(TopTransactionContext);
  item = palloc(sizeof(AfterTriggerCallbackItem));
  item->callback = callback;
  item->arg = arg;
  if (afterTriggers.query_depth >= 0)
  {
    AfterTriggersQueryData *qs =
      &afterTriggers.query_stack[afterTriggers.query_depth];

    qs->batch_callbacks = lappend(qs->batch_callbacks, item);
  }
  else
    afterTriggers.batch_callbacks =
      lappend(afterTriggers.batch_callbacks, item);
  MemoryContextSwitchTo(oldcxt);
}

/*
 * FireAfterTriggerBatchCallbacks
 *    Invoke all callbacks in the given list.
 *
 * Memory cleanup of the list and its items is handled by the caller
 * (AfterTriggerFreeQuery for query-level callbacks, AfterTriggerEndXact
 * for top-level deferred callbacks).
 */
static void
FireAfterTriggerBatchCallbacks(List *callbacks)
{
  ListCell   *lc;

  Assert(afterTriggers.firing_depth > 0);
  afterTriggers.firing_batch_callbacks = true;
  foreach(lc, callbacks)
  {
    AfterTriggerCallbackItem *item = lfirst(lc);

    item->callback(item->arg);
  }
  afterTriggers.firing_batch_callbacks = false;
}

/*
 * AfterTriggerIsActive
 *    Returns true if we're inside the after-trigger framework where
 *    registered batch callbacks will actually be invoked.
 *
 * This is false during validateForeignKeyConstraint(), which calls
 * RI trigger functions directly outside the after-trigger framework.
 */
bool
AfterTriggerIsActive(void)
{
  return afterTriggers.firing_depth > 0;
}

Coverage Report

Created: 2026-08-14 06:37