/src/postgres/src/backend/executor/nodeModifyTable.c

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/*-------------------------------------------------------------------------
 *
 * nodeModifyTable.c
 *    routines to handle ModifyTable nodes.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/executor/nodeModifyTable.c
 *
 *-------------------------------------------------------------------------
 */
/* INTERFACE ROUTINES
 *    ExecInitModifyTable - initialize the ModifyTable node
 *    ExecModifyTable   - retrieve the next tuple from the node
 *    ExecEndModifyTable  - shut down the ModifyTable node
 *    ExecReScanModifyTable - rescan the ModifyTable node
 *
 *   NOTES
 *    The ModifyTable node receives input from its outerPlan, which is
 *    the data to insert for INSERT cases, the changed columns' new
 *    values plus row-locating info for UPDATE and MERGE cases, or just the
 *    row-locating info for DELETE cases.
 *
 *    The relation to modify can be an ordinary table, a foreign table, or a
 *    view.  If it's a view, either it has sufficient INSTEAD OF triggers or
 *    this node executes only MERGE ... DO NOTHING.  If the original MERGE
 *    targeted a view not in one of those two categories, earlier processing
 *    already pointed the ModifyTable result relation to an underlying
 *    relation of that other view.  This node does process
 *    ri_WithCheckOptions, which may have expressions from those other,
 *    automatically updatable views.
 *
 *    MERGE runs a join between the source relation and the target table.
 *    If any WHEN NOT MATCHED [BY TARGET] clauses are present, then the join
 *    is an outer join that might output tuples without a matching target
 *    tuple.  In this case, any unmatched target tuples will have NULL
 *    row-locating info, and only INSERT can be run.  But for matched target
 *    tuples, the row-locating info is used to determine the tuple to UPDATE
 *    or DELETE.  When all clauses are WHEN MATCHED or WHEN NOT MATCHED BY
 *    SOURCE, all tuples produced by the join will include a matching target
 *    tuple, so all tuples contain row-locating info.
 *
 *    If the query specifies RETURNING, then the ModifyTable returns a
 *    RETURNING tuple after completing each row insert, update, or delete.
 *    It must be called again to continue the operation.  Without RETURNING,
 *    we just loop within the node until all the work is done, then
 *    return NULL.  This avoids useless call/return overhead.
 */

#include "postgres.h"

#include "access/htup_details.h"
#include "access/tableam.h"
#include "access/xact.h"
#include "commands/trigger.h"
#include "executor/execPartition.h"
#include "executor/executor.h"
#include "executor/nodeModifyTable.h"
#include "foreign/fdwapi.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/optimizer.h"
#include "rewrite/rewriteHandler.h"
#include "rewrite/rewriteManip.h"
#include "storage/lmgr.h"
#include "utils/builtins.h"
#include "utils/datum.h"
#include "utils/rel.h"
#include "utils/snapmgr.h"


typedef struct MTTargetRelLookup
{
  Oid     relationOid;  /* hash key, must be first */
  int     relationIndex;  /* rel's index in resultRelInfo[] array */
} MTTargetRelLookup;

/*
 * Context struct for a ModifyTable operation, containing basic execution
 * state and some output variables populated by ExecUpdateAct() and
 * ExecDeleteAct() to report the result of their actions to callers.
 */
typedef struct ModifyTableContext
{
  /* Operation state */
  ModifyTableState *mtstate;
  EPQState   *epqstate;
  EState     *estate;

  /*
   * Slot containing tuple obtained from ModifyTable's subplan.  Used to
   * access "junk" columns that are not going to be stored.
   */
  TupleTableSlot *planSlot;

  /*
   * Information about the changes that were made concurrently to a tuple
   * being updated or deleted
   */
  TM_FailureData tmfd;

  /*
   * The tuple deleted when doing a cross-partition UPDATE with a RETURNING
   * clause that refers to OLD columns (converted to the root's tuple
   * descriptor).
   */
  TupleTableSlot *cpDeletedSlot;

  /*
   * The tuple projected by the INSERT's RETURNING clause, when doing a
   * cross-partition UPDATE
   */
  TupleTableSlot *cpUpdateReturningSlot;
} ModifyTableContext;

/*
 * Context struct containing output data specific to UPDATE operations.
 */
typedef struct UpdateContext
{
  bool    crossPartUpdate;  /* was it a cross-partition update? */
  TU_UpdateIndexes updateIndexes; /* Which index updates are required? */

  /*
   * Lock mode to acquire on the latest tuple version before performing
   * EvalPlanQual on it
   */
  LockTupleMode lockmode;
} UpdateContext;


static void ExecBatchInsert(ModifyTableState *mtstate,
              ResultRelInfo *resultRelInfo,
              TupleTableSlot **slots,
              TupleTableSlot **planSlots,
              int numSlots,
              EState *estate,
              bool canSetTag);
static void ExecPendingInserts(EState *estate);
static void ExecCrossPartitionUpdateForeignKey(ModifyTableContext *context,
                         ResultRelInfo *sourcePartInfo,
                         ResultRelInfo *destPartInfo,
                         ItemPointer tupleid,
                         TupleTableSlot *oldslot,
                         TupleTableSlot *newslot);
static bool ExecOnConflictUpdate(ModifyTableContext *context,
                 ResultRelInfo *resultRelInfo,
                 ItemPointer conflictTid,
                 TupleTableSlot *excludedSlot,
                 bool canSetTag,
                 TupleTableSlot **returning);
static TupleTableSlot *ExecPrepareTupleRouting(ModifyTableState *mtstate,
                         EState *estate,
                         PartitionTupleRouting *proute,
                         ResultRelInfo *targetRelInfo,
                         TupleTableSlot *slot,
                         ResultRelInfo **partRelInfo);

static TupleTableSlot *ExecMerge(ModifyTableContext *context,
                 ResultRelInfo *resultRelInfo,
                 ItemPointer tupleid,
                 HeapTuple oldtuple,
                 bool canSetTag);
static void ExecInitMerge(ModifyTableState *mtstate, EState *estate);
static TupleTableSlot *ExecMergeMatched(ModifyTableContext *context,
                    ResultRelInfo *resultRelInfo,
                    ItemPointer tupleid,
                    HeapTuple oldtuple,
                    bool canSetTag,
                    bool *matched);
static TupleTableSlot *ExecMergeNotMatched(ModifyTableContext *context,
                       ResultRelInfo *resultRelInfo,
                       bool canSetTag);


/*
 * Verify that the tuples to be produced by INSERT match the
 * target relation's rowtype
 *
 * We do this to guard against stale plans.  If plan invalidation is
 * functioning properly then we should never get a failure here, but better
 * safe than sorry.  Note that this is called after we have obtained lock
 * on the target rel, so the rowtype can't change underneath us.
 *
 * The plan output is represented by its targetlist, because that makes
 * handling the dropped-column case easier.
 *
 * We used to use this for UPDATE as well, but now the equivalent checks
 * are done in ExecBuildUpdateProjection.
 */
static void
ExecCheckPlanOutput(Relation resultRel, List *targetList)
{
  TupleDesc resultDesc = RelationGetDescr(resultRel);
  int     attno = 0;
  ListCell   *lc;

  foreach(lc, targetList)
  {
    TargetEntry *tle = (TargetEntry *) lfirst(lc);
    Form_pg_attribute attr;

    Assert(!tle->resjunk);  /* caller removed junk items already */

    if (attno >= resultDesc->natts)
      ereport(ERROR,
          (errcode(ERRCODE_DATATYPE_MISMATCH),
           errmsg("table row type and query-specified row type do not match"),
           errdetail("Query has too many columns.")));
    attr = TupleDescAttr(resultDesc, attno);
    attno++;

    /*
     * Special cases here should match planner's expand_insert_targetlist.
     */
    if (attr->attisdropped)
    {
      /*
       * For a dropped column, we can't check atttypid (it's likely 0).
       * In any case the planner has most likely inserted an INT4 null.
       * What we insist on is just *some* NULL constant.
       */
      if (!IsA(tle->expr, Const) ||
        !((Const *) tle->expr)->constisnull)
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("table row type and query-specified row type do not match"),
             errdetail("Query provides a value for a dropped column at ordinal position %d.",
                   attno)));
    }
    else if (attr->attgenerated)
    {
      /*
       * For a generated column, the planner will have inserted a null
       * of the column's base type (to avoid possibly failing on domain
       * not-null constraints).  It doesn't seem worth insisting on that
       * exact type though, since a null value is type-independent.  As
       * above, just insist on *some* NULL constant.
       */
      if (!IsA(tle->expr, Const) ||
        !((Const *) tle->expr)->constisnull)
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("table row type and query-specified row type do not match"),
             errdetail("Query provides a value for a generated column at ordinal position %d.",
                   attno)));
    }
    else
    {
      /* Normal case: demand type match */
      if (exprType((Node *) tle->expr) != attr->atttypid)
        ereport(ERROR,
            (errcode(ERRCODE_DATATYPE_MISMATCH),
             errmsg("table row type and query-specified row type do not match"),
             errdetail("Table has type %s at ordinal position %d, but query expects %s.",
                   format_type_be(attr->atttypid),
                   attno,
                   format_type_be(exprType((Node *) tle->expr)))));
    }
  }
  if (attno != resultDesc->natts)
    ereport(ERROR,
        (errcode(ERRCODE_DATATYPE_MISMATCH),
         errmsg("table row type and query-specified row type do not match"),
         errdetail("Query has too few columns.")));
}

/*
 * ExecProcessReturning --- evaluate a RETURNING list
 *
 * context: context for the ModifyTable operation
 * resultRelInfo: current result rel
 * cmdType: operation/merge action performed (INSERT, UPDATE, or DELETE)
 * oldSlot: slot holding old tuple deleted or updated
 * newSlot: slot holding new tuple inserted or updated
 * planSlot: slot holding tuple returned by top subplan node
 *
 * Note: If oldSlot and newSlot are NULL, the FDW should have already provided
 * econtext's scan tuple and its old & new tuples are not needed (FDW direct-
 * modify is disabled if the RETURNING list refers to any OLD/NEW values).
 *
 * Returns a slot holding the result tuple
 */
static TupleTableSlot *
ExecProcessReturning(ModifyTableContext *context,
           ResultRelInfo *resultRelInfo,
           CmdType cmdType,
           TupleTableSlot *oldSlot,
           TupleTableSlot *newSlot,
           TupleTableSlot *planSlot)
{
  EState     *estate = context->estate;
  ProjectionInfo *projectReturning = resultRelInfo->ri_projectReturning;
  ExprContext *econtext = projectReturning->pi_exprContext;

  /* Make tuple and any needed join variables available to ExecProject */
  switch (cmdType)
  {
    case CMD_INSERT:
    case CMD_UPDATE:
      /* return new tuple by default */
      if (newSlot)
        econtext->ecxt_scantuple = newSlot;
      break;

    case CMD_DELETE:
      /* return old tuple by default */
      if (oldSlot)
        econtext->ecxt_scantuple = oldSlot;
      break;

    default:
      elog(ERROR, "unrecognized commandType: %d", (int) cmdType);
  }
  econtext->ecxt_outertuple = planSlot;

  /* Make old/new tuples available to ExecProject, if required */
  if (oldSlot)
    econtext->ecxt_oldtuple = oldSlot;
  else if (projectReturning->pi_state.flags & EEO_FLAG_HAS_OLD)
    econtext->ecxt_oldtuple = ExecGetAllNullSlot(estate, resultRelInfo);
  else
    econtext->ecxt_oldtuple = NULL; /* No references to OLD columns */

  if (newSlot)
    econtext->ecxt_newtuple = newSlot;
  else if (projectReturning->pi_state.flags & EEO_FLAG_HAS_NEW)
    econtext->ecxt_newtuple = ExecGetAllNullSlot(estate, resultRelInfo);
  else
    econtext->ecxt_newtuple = NULL; /* No references to NEW columns */

  /*
   * Tell ExecProject whether or not the OLD/NEW rows actually exist.  This
   * information is required to evaluate ReturningExpr nodes and also in
   * ExecEvalSysVar() and ExecEvalWholeRowVar().
   */
  if (oldSlot == NULL)
    projectReturning->pi_state.flags |= EEO_FLAG_OLD_IS_NULL;
  else
    projectReturning->pi_state.flags &= ~EEO_FLAG_OLD_IS_NULL;

  if (newSlot == NULL)
    projectReturning->pi_state.flags |= EEO_FLAG_NEW_IS_NULL;
  else
    projectReturning->pi_state.flags &= ~EEO_FLAG_NEW_IS_NULL;

  /* Compute the RETURNING expressions */
  return ExecProject(projectReturning);
}

/*
 * ExecCheckTupleVisible -- verify tuple is visible
 *
 * It would not be consistent with guarantees of the higher isolation levels to
 * proceed with avoiding insertion (taking speculative insertion's alternative
 * path) on the basis of another tuple that is not visible to MVCC snapshot.
 * Check for the need to raise a serialization failure, and do so as necessary.
 */
static void
ExecCheckTupleVisible(EState *estate,
            Relation rel,
            TupleTableSlot *slot)
{
  if (!IsolationUsesXactSnapshot())
    return;

  if (!table_tuple_satisfies_snapshot(rel, slot, estate->es_snapshot))
  {
    Datum   xminDatum;
    TransactionId xmin;
    bool    isnull;

    xminDatum = slot_getsysattr(slot, MinTransactionIdAttributeNumber, &isnull);
    Assert(!isnull);
    xmin = DatumGetTransactionId(xminDatum);

    /*
     * We should not raise a serialization failure if the conflict is
     * against a tuple inserted by our own transaction, even if it's not
     * visible to our snapshot.  (This would happen, for example, if
     * conflicting keys are proposed for insertion in a single command.)
     */
    if (!TransactionIdIsCurrentTransactionId(xmin))
      ereport(ERROR,
          (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
           errmsg("could not serialize access due to concurrent update")));
  }
}

/*
 * ExecCheckTIDVisible -- convenience variant of ExecCheckTupleVisible()
 */
static void
ExecCheckTIDVisible(EState *estate,
          ResultRelInfo *relinfo,
          ItemPointer tid,
          TupleTableSlot *tempSlot)
{
  Relation  rel = relinfo->ri_RelationDesc;

  /* Redundantly check isolation level */
  if (!IsolationUsesXactSnapshot())
    return;

  if (!table_tuple_fetch_row_version(rel, tid, SnapshotAny, tempSlot))
    elog(ERROR, "failed to fetch conflicting tuple for ON CONFLICT");
  ExecCheckTupleVisible(estate, rel, tempSlot);
  ExecClearTuple(tempSlot);
}

/*
 * Initialize generated columns handling for a tuple
 *
 * This fills the resultRelInfo's ri_GeneratedExprsI/ri_NumGeneratedNeededI or
 * ri_GeneratedExprsU/ri_NumGeneratedNeededU fields, depending on cmdtype.
 * This is used only for stored generated columns.
 *
 * If cmdType == CMD_UPDATE, the ri_extraUpdatedCols field is filled too.
 * This is used by both stored and virtual generated columns.
 *
 * Note: usually, a given query would need only one of ri_GeneratedExprsI and
 * ri_GeneratedExprsU per result rel; but MERGE can need both, and so can
 * cross-partition UPDATEs, since a partition might be the target of both
 * UPDATE and INSERT actions.
 */
void
ExecInitGenerated(ResultRelInfo *resultRelInfo,
          EState *estate,
          CmdType cmdtype)
{
  Relation  rel = resultRelInfo->ri_RelationDesc;
  TupleDesc tupdesc = RelationGetDescr(rel);
  int     natts = tupdesc->natts;
  ExprState **ri_GeneratedExprs;
  int     ri_NumGeneratedNeeded;
  Bitmapset  *updatedCols;
  MemoryContext oldContext;

  /* Nothing to do if no generated columns */
  if (!(tupdesc->constr && (tupdesc->constr->has_generated_stored || tupdesc->constr->has_generated_virtual)))
    return;

  /*
   * In an UPDATE, we can skip computing any generated columns that do not
   * depend on any UPDATE target column.  But if there is a BEFORE ROW
   * UPDATE trigger, we cannot skip because the trigger might change more
   * columns.
   */
  if (cmdtype == CMD_UPDATE &&
    !(rel->trigdesc && rel->trigdesc->trig_update_before_row))
    updatedCols = ExecGetUpdatedCols(resultRelInfo, estate);
  else
    updatedCols = NULL;

  /*
   * Make sure these data structures are built in the per-query memory
   * context so they'll survive throughout the query.
   */
  oldContext = MemoryContextSwitchTo(estate->es_query_cxt);

  ri_GeneratedExprs = (ExprState **) palloc0(natts * sizeof(ExprState *));
  ri_NumGeneratedNeeded = 0;

  for (int i = 0; i < natts; i++)
  {
    char    attgenerated = TupleDescAttr(tupdesc, i)->attgenerated;

    if (attgenerated)
    {
      Expr     *expr;

      /* Fetch the GENERATED AS expression tree */
      expr = (Expr *) build_column_default(rel, i + 1);
      if (expr == NULL)
        elog(ERROR, "no generation expression found for column number %d of table \"%s\"",
           i + 1, RelationGetRelationName(rel));

      /*
       * If it's an update with a known set of update target columns,
       * see if we can skip the computation.
       */
      if (updatedCols)
      {
        Bitmapset  *attrs_used = NULL;

        pull_varattnos((Node *) expr, 1, &attrs_used);

        if (!bms_overlap(updatedCols, attrs_used))
          continue; /* need not update this column */
      }

      /* No luck, so prepare the expression for execution */
      if (attgenerated == ATTRIBUTE_GENERATED_STORED)
      {
        ri_GeneratedExprs[i] = ExecPrepareExpr(expr, estate);
        ri_NumGeneratedNeeded++;
      }

      /* If UPDATE, mark column in resultRelInfo->ri_extraUpdatedCols */
      if (cmdtype == CMD_UPDATE)
        resultRelInfo->ri_extraUpdatedCols =
          bms_add_member(resultRelInfo->ri_extraUpdatedCols,
                   i + 1 - FirstLowInvalidHeapAttributeNumber);
    }
  }

  if (ri_NumGeneratedNeeded == 0)
  {
    /* didn't need it after all */
    pfree(ri_GeneratedExprs);
    ri_GeneratedExprs = NULL;
  }

  /* Save in appropriate set of fields */
  if (cmdtype == CMD_UPDATE)
  {
    /* Don't call twice */
    Assert(resultRelInfo->ri_GeneratedExprsU == NULL);

    resultRelInfo->ri_GeneratedExprsU = ri_GeneratedExprs;
    resultRelInfo->ri_NumGeneratedNeededU = ri_NumGeneratedNeeded;

    resultRelInfo->ri_extraUpdatedCols_valid = true;
  }
  else
  {
    /* Don't call twice */
    Assert(resultRelInfo->ri_GeneratedExprsI == NULL);

    resultRelInfo->ri_GeneratedExprsI = ri_GeneratedExprs;
    resultRelInfo->ri_NumGeneratedNeededI = ri_NumGeneratedNeeded;
  }

  MemoryContextSwitchTo(oldContext);
}

/*
 * Compute stored generated columns for a tuple
 */
void
ExecComputeStoredGenerated(ResultRelInfo *resultRelInfo,
               EState *estate, TupleTableSlot *slot,
               CmdType cmdtype)
{
  Relation  rel = resultRelInfo->ri_RelationDesc;
  TupleDesc tupdesc = RelationGetDescr(rel);
  int     natts = tupdesc->natts;
  ExprContext *econtext = GetPerTupleExprContext(estate);
  ExprState **ri_GeneratedExprs;
  MemoryContext oldContext;
  Datum    *values;
  bool     *nulls;

  /* We should not be called unless this is true */
  Assert(tupdesc->constr && tupdesc->constr->has_generated_stored);

  /*
   * Initialize the expressions if we didn't already, and check whether we
   * can exit early because nothing needs to be computed.
   */
  if (cmdtype == CMD_UPDATE)
  {
    if (resultRelInfo->ri_GeneratedExprsU == NULL)
      ExecInitGenerated(resultRelInfo, estate, cmdtype);
    if (resultRelInfo->ri_NumGeneratedNeededU == 0)
      return;
    ri_GeneratedExprs = resultRelInfo->ri_GeneratedExprsU;
  }
  else
  {
    if (resultRelInfo->ri_GeneratedExprsI == NULL)
      ExecInitGenerated(resultRelInfo, estate, cmdtype);
    /* Early exit is impossible given the prior Assert */
    Assert(resultRelInfo->ri_NumGeneratedNeededI > 0);
    ri_GeneratedExprs = resultRelInfo->ri_GeneratedExprsI;
  }

  oldContext = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));

  values = palloc(sizeof(*values) * natts);
  nulls = palloc(sizeof(*nulls) * natts);

  slot_getallattrs(slot);
  memcpy(nulls, slot->tts_isnull, sizeof(*nulls) * natts);

  for (int i = 0; i < natts; i++)
  {
    CompactAttribute *attr = TupleDescCompactAttr(tupdesc, i);

    if (ri_GeneratedExprs[i])
    {
      Datum   val;
      bool    isnull;

      Assert(TupleDescAttr(tupdesc, i)->attgenerated == ATTRIBUTE_GENERATED_STORED);

      econtext->ecxt_scantuple = slot;

      val = ExecEvalExpr(ri_GeneratedExprs[i], econtext, &isnull);

      /*
       * We must make a copy of val as we have no guarantees about where
       * memory for a pass-by-reference Datum is located.
       */
      if (!isnull)
        val = datumCopy(val, attr->attbyval, attr->attlen);

      values[i] = val;
      nulls[i] = isnull;
    }
    else
    {
      if (!nulls[i])
        values[i] = datumCopy(slot->tts_values[i], attr->attbyval, attr->attlen);
    }
  }

  ExecClearTuple(slot);
  memcpy(slot->tts_values, values, sizeof(*values) * natts);
  memcpy(slot->tts_isnull, nulls, sizeof(*nulls) * natts);
  ExecStoreVirtualTuple(slot);
  ExecMaterializeSlot(slot);

  MemoryContextSwitchTo(oldContext);
}

/*
 * ExecInitInsertProjection
 *    Do one-time initialization of projection data for INSERT tuples.
 *
 * INSERT queries may need a projection to filter out junk attrs in the tlist.
 *
 * This is also a convenient place to verify that the
 * output of an INSERT matches the target table.
 */
static void
ExecInitInsertProjection(ModifyTableState *mtstate,
             ResultRelInfo *resultRelInfo)
{
  ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
  Plan     *subplan = outerPlan(node);
  EState     *estate = mtstate->ps.state;
  List     *insertTargetList = NIL;
  bool    need_projection = false;
  ListCell   *l;

  /* Extract non-junk columns of the subplan's result tlist. */
  foreach(l, subplan->targetlist)
  {
    TargetEntry *tle = (TargetEntry *) lfirst(l);

    if (!tle->resjunk)
      insertTargetList = lappend(insertTargetList, tle);
    else
      need_projection = true;
  }

  /*
   * The junk-free list must produce a tuple suitable for the result
   * relation.
   */
  ExecCheckPlanOutput(resultRelInfo->ri_RelationDesc, insertTargetList);

  /* We'll need a slot matching the table's format. */
  resultRelInfo->ri_newTupleSlot =
    table_slot_create(resultRelInfo->ri_RelationDesc,
              &estate->es_tupleTable);

  /* Build ProjectionInfo if needed (it probably isn't). */
  if (need_projection)
  {
    TupleDesc relDesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);

    /* need an expression context to do the projection */
    if (mtstate->ps.ps_ExprContext == NULL)
      ExecAssignExprContext(estate, &mtstate->ps);

    resultRelInfo->ri_projectNew =
      ExecBuildProjectionInfo(insertTargetList,
                  mtstate->ps.ps_ExprContext,
                  resultRelInfo->ri_newTupleSlot,
                  &mtstate->ps,
                  relDesc);
  }

  resultRelInfo->ri_projectNewInfoValid = true;
}

/*
 * ExecInitUpdateProjection
 *    Do one-time initialization of projection data for UPDATE tuples.
 *
 * UPDATE always needs a projection, because (1) there's always some junk
 * attrs, and (2) we may need to merge values of not-updated columns from
 * the old tuple into the final tuple.  In UPDATE, the tuple arriving from
 * the subplan contains only new values for the changed columns, plus row
 * identity info in the junk attrs.
 *
 * This is "one-time" for any given result rel, but we might touch more than
 * one result rel in the course of an inherited UPDATE, and each one needs
 * its own projection due to possible column order variation.
 *
 * This is also a convenient place to verify that the output of an UPDATE
 * matches the target table (ExecBuildUpdateProjection does that).
 */
static void
ExecInitUpdateProjection(ModifyTableState *mtstate,
             ResultRelInfo *resultRelInfo)
{
  ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
  Plan     *subplan = outerPlan(node);
  EState     *estate = mtstate->ps.state;
  TupleDesc relDesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);
  int     whichrel;
  List     *updateColnos;

  /*
   * Usually, mt_lastResultIndex matches the target rel.  If it happens not
   * to, we can get the index the hard way with an integer division.
   */
  whichrel = mtstate->mt_lastResultIndex;
  if (resultRelInfo != mtstate->resultRelInfo + whichrel)
  {
    whichrel = resultRelInfo - mtstate->resultRelInfo;
    Assert(whichrel >= 0 && whichrel < mtstate->mt_nrels);
  }

  updateColnos = (List *) list_nth(mtstate->mt_updateColnosLists, whichrel);

  /*
   * For UPDATE, we use the old tuple to fill up missing values in the tuple
   * produced by the subplan to get the new tuple.  We need two slots, both
   * matching the table's desired format.
   */
  resultRelInfo->ri_oldTupleSlot =
    table_slot_create(resultRelInfo->ri_RelationDesc,
              &estate->es_tupleTable);
  resultRelInfo->ri_newTupleSlot =
    table_slot_create(resultRelInfo->ri_RelationDesc,
              &estate->es_tupleTable);

  /* need an expression context to do the projection */
  if (mtstate->ps.ps_ExprContext == NULL)
    ExecAssignExprContext(estate, &mtstate->ps);

  resultRelInfo->ri_projectNew =
    ExecBuildUpdateProjection(subplan->targetlist,
                  false,  /* subplan did the evaluation */
                  updateColnos,
                  relDesc,
                  mtstate->ps.ps_ExprContext,
                  resultRelInfo->ri_newTupleSlot,
                  &mtstate->ps);

  resultRelInfo->ri_projectNewInfoValid = true;
}

/*
 * ExecGetInsertNewTuple
 *    This prepares a "new" tuple ready to be inserted into given result
 *    relation, by removing any junk columns of the plan's output tuple
 *    and (if necessary) coercing the tuple to the right tuple format.
 */
static TupleTableSlot *
ExecGetInsertNewTuple(ResultRelInfo *relinfo,
            TupleTableSlot *planSlot)
{
  ProjectionInfo *newProj = relinfo->ri_projectNew;
  ExprContext *econtext;

  /*
   * If there's no projection to be done, just make sure the slot is of the
   * right type for the target rel.  If the planSlot is the right type we
   * can use it as-is, else copy the data into ri_newTupleSlot.
   */
  if (newProj == NULL)
  {
    if (relinfo->ri_newTupleSlot->tts_ops != planSlot->tts_ops)
    {
      ExecCopySlot(relinfo->ri_newTupleSlot, planSlot);
      return relinfo->ri_newTupleSlot;
    }
    else
      return planSlot;
  }

  /*
   * Else project; since the projection output slot is ri_newTupleSlot, this
   * will also fix any slot-type problem.
   *
   * Note: currently, this is dead code, because INSERT cases don't receive
   * any junk columns so there's never a projection to be done.
   */
  econtext = newProj->pi_exprContext;
  econtext->ecxt_outertuple = planSlot;
  return ExecProject(newProj);
}

/*
 * ExecGetUpdateNewTuple
 *    This prepares a "new" tuple by combining an UPDATE subplan's output
 *    tuple (which contains values of changed columns) with unchanged
 *    columns taken from the old tuple.
 *
 * The subplan tuple might also contain junk columns, which are ignored.
 * Note that the projection also ensures we have a slot of the right type.
 */
TupleTableSlot *
ExecGetUpdateNewTuple(ResultRelInfo *relinfo,
            TupleTableSlot *planSlot,
            TupleTableSlot *oldSlot)
{
  ProjectionInfo *newProj = relinfo->ri_projectNew;
  ExprContext *econtext;

  /* Use a few extra Asserts to protect against outside callers */
  Assert(relinfo->ri_projectNewInfoValid);
  Assert(planSlot != NULL && !TTS_EMPTY(planSlot));
  Assert(oldSlot != NULL && !TTS_EMPTY(oldSlot));

  econtext = newProj->pi_exprContext;
  econtext->ecxt_outertuple = planSlot;
  econtext->ecxt_scantuple = oldSlot;
  return ExecProject(newProj);
}

/* ----------------------------------------------------------------
 *    ExecInsert
 *
 *    For INSERT, we have to insert the tuple into the target relation
 *    (or partition thereof) and insert appropriate tuples into the index
 *    relations.
 *
 *    slot contains the new tuple value to be stored.
 *
 *    Returns RETURNING result if any, otherwise NULL.
 *    *inserted_tuple is the tuple that's effectively inserted;
 *    *insert_destrel is the relation where it was inserted.
 *    These are only set on success.
 *
 *    This may change the currently active tuple conversion map in
 *    mtstate->mt_transition_capture, so the callers must take care to
 *    save the previous value to avoid losing track of it.
 * ----------------------------------------------------------------
 */
static TupleTableSlot *
ExecInsert(ModifyTableContext *context,
       ResultRelInfo *resultRelInfo,
       TupleTableSlot *slot,
       bool canSetTag,
       TupleTableSlot **inserted_tuple,
       ResultRelInfo **insert_destrel)
{
  ModifyTableState *mtstate = context->mtstate;
  EState     *estate = context->estate;
  Relation  resultRelationDesc;
  List     *recheckIndexes = NIL;
  TupleTableSlot *planSlot = context->planSlot;
  TupleTableSlot *result = NULL;
  TransitionCaptureState *ar_insert_trig_tcs;
  ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
  OnConflictAction onconflict = node->onConflictAction;
  PartitionTupleRouting *proute = mtstate->mt_partition_tuple_routing;
  MemoryContext oldContext;

  /*
   * If the input result relation is a partitioned table, find the leaf
   * partition to insert the tuple into.
   */
  if (proute)
  {
    ResultRelInfo *partRelInfo;

    slot = ExecPrepareTupleRouting(mtstate, estate, proute,
                     resultRelInfo, slot,
                     &partRelInfo);
    resultRelInfo = partRelInfo;
  }

  ExecMaterializeSlot(slot);

  resultRelationDesc = resultRelInfo->ri_RelationDesc;

  /*
   * Open the table's indexes, if we have not done so already, so that we
   * can add new index entries for the inserted tuple.
   */
  if (resultRelationDesc->rd_rel->relhasindex &&
    resultRelInfo->ri_IndexRelationDescs == NULL)
    ExecOpenIndices(resultRelInfo, onconflict != ONCONFLICT_NONE);

  /*
   * BEFORE ROW INSERT Triggers.
   *
   * Note: We fire BEFORE ROW TRIGGERS for every attempted insertion in an
   * INSERT ... ON CONFLICT statement.  We cannot check for constraint
   * violations before firing these triggers, because they can change the
   * values to insert.  Also, they can run arbitrary user-defined code with
   * side-effects that we can't cancel by just not inserting the tuple.
   */
  if (resultRelInfo->ri_TrigDesc &&
    resultRelInfo->ri_TrigDesc->trig_insert_before_row)
  {
    /* Flush any pending inserts, so rows are visible to the triggers */
    if (estate->es_insert_pending_result_relations != NIL)
      ExecPendingInserts(estate);

    if (!ExecBRInsertTriggers(estate, resultRelInfo, slot))
      return NULL;   /* "do nothing" */
  }

  /* INSTEAD OF ROW INSERT Triggers */
  if (resultRelInfo->ri_TrigDesc &&
    resultRelInfo->ri_TrigDesc->trig_insert_instead_row)
  {
    if (!ExecIRInsertTriggers(estate, resultRelInfo, slot))
      return NULL;   /* "do nothing" */
  }
  else if (resultRelInfo->ri_FdwRoutine)
  {
    /*
     * GENERATED expressions might reference the tableoid column, so
     * (re-)initialize tts_tableOid before evaluating them.
     */
    slot->tts_tableOid = RelationGetRelid(resultRelInfo->ri_RelationDesc);

    /*
     * Compute stored generated columns
     */
    if (resultRelationDesc->rd_att->constr &&
      resultRelationDesc->rd_att->constr->has_generated_stored)
      ExecComputeStoredGenerated(resultRelInfo, estate, slot,
                     CMD_INSERT);

    /*
     * If the FDW supports batching, and batching is requested, accumulate
     * rows and insert them in batches. Otherwise use the per-row inserts.
     */
    if (resultRelInfo->ri_BatchSize > 1)
    {
      bool    flushed = false;

      /*
       * When we've reached the desired batch size, perform the
       * insertion.
       */
      if (resultRelInfo->ri_NumSlots == resultRelInfo->ri_BatchSize)
      {
        ExecBatchInsert(mtstate, resultRelInfo,
                resultRelInfo->ri_Slots,
                resultRelInfo->ri_PlanSlots,
                resultRelInfo->ri_NumSlots,
                estate, canSetTag);
        flushed = true;
      }

      oldContext = MemoryContextSwitchTo(estate->es_query_cxt);

      if (resultRelInfo->ri_Slots == NULL)
      {
        resultRelInfo->ri_Slots = palloc(sizeof(TupleTableSlot *) *
                         resultRelInfo->ri_BatchSize);
        resultRelInfo->ri_PlanSlots = palloc(sizeof(TupleTableSlot *) *
                           resultRelInfo->ri_BatchSize);
      }

      /*
       * Initialize the batch slots. We don't know how many slots will
       * be needed, so we initialize them as the batch grows, and we
       * keep them across batches. To mitigate an inefficiency in how
       * resource owner handles objects with many references (as with
       * many slots all referencing the same tuple descriptor) we copy
       * the appropriate tuple descriptor for each slot.
       */
      if (resultRelInfo->ri_NumSlots >= resultRelInfo->ri_NumSlotsInitialized)
      {
        TupleDesc tdesc = CreateTupleDescCopy(slot->tts_tupleDescriptor);
        TupleDesc plan_tdesc =
          CreateTupleDescCopy(planSlot->tts_tupleDescriptor);

        resultRelInfo->ri_Slots[resultRelInfo->ri_NumSlots] =
          MakeSingleTupleTableSlot(tdesc, slot->tts_ops);

        resultRelInfo->ri_PlanSlots[resultRelInfo->ri_NumSlots] =
          MakeSingleTupleTableSlot(plan_tdesc, planSlot->tts_ops);

        /* remember how many batch slots we initialized */
        resultRelInfo->ri_NumSlotsInitialized++;
      }

      ExecCopySlot(resultRelInfo->ri_Slots[resultRelInfo->ri_NumSlots],
             slot);

      ExecCopySlot(resultRelInfo->ri_PlanSlots[resultRelInfo->ri_NumSlots],
             planSlot);

      /*
       * If these are the first tuples stored in the buffers, add the
       * target rel and the mtstate to the
       * es_insert_pending_result_relations and
       * es_insert_pending_modifytables lists respectively, except in
       * the case where flushing was done above, in which case they
       * would already have been added to the lists, so no need to do
       * this.
       */
      if (resultRelInfo->ri_NumSlots == 0 && !flushed)
      {
        Assert(!list_member_ptr(estate->es_insert_pending_result_relations,
                    resultRelInfo));
        estate->es_insert_pending_result_relations =
          lappend(estate->es_insert_pending_result_relations,
              resultRelInfo);
        estate->es_insert_pending_modifytables =
          lappend(estate->es_insert_pending_modifytables, mtstate);
      }
      Assert(list_member_ptr(estate->es_insert_pending_result_relations,
                   resultRelInfo));

      resultRelInfo->ri_NumSlots++;

      MemoryContextSwitchTo(oldContext);

      return NULL;
    }

    /*
     * insert into foreign table: let the FDW do it
     */
    slot = resultRelInfo->ri_FdwRoutine->ExecForeignInsert(estate,
                                 resultRelInfo,
                                 slot,
                                 planSlot);

    if (slot == NULL)   /* "do nothing" */
      return NULL;

    /*
     * AFTER ROW Triggers or RETURNING expressions might reference the
     * tableoid column, so (re-)initialize tts_tableOid before evaluating
     * them.  (This covers the case where the FDW replaced the slot.)
     */
    slot->tts_tableOid = RelationGetRelid(resultRelInfo->ri_RelationDesc);
  }
  else
  {
    WCOKind   wco_kind;

    /*
     * Constraints and GENERATED expressions might reference the tableoid
     * column, so (re-)initialize tts_tableOid before evaluating them.
     */
    slot->tts_tableOid = RelationGetRelid(resultRelationDesc);

    /*
     * Compute stored generated columns
     */
    if (resultRelationDesc->rd_att->constr &&
      resultRelationDesc->rd_att->constr->has_generated_stored)
      ExecComputeStoredGenerated(resultRelInfo, estate, slot,
                     CMD_INSERT);

    /*
     * Check any RLS WITH CHECK policies.
     *
     * Normally we should check INSERT policies. But if the insert is the
     * result of a partition key update that moved the tuple to a new
     * partition, we should instead check UPDATE policies, because we are
     * executing policies defined on the target table, and not those
     * defined on the child partitions.
     *
     * If we're running MERGE, we refer to the action that we're executing
     * to know if we're doing an INSERT or UPDATE to a partition table.
     */
    if (mtstate->operation == CMD_UPDATE)
      wco_kind = WCO_RLS_UPDATE_CHECK;
    else if (mtstate->operation == CMD_MERGE)
      wco_kind = (mtstate->mt_merge_action->mas_action->commandType == CMD_UPDATE) ?
        WCO_RLS_UPDATE_CHECK : WCO_RLS_INSERT_CHECK;
    else
      wco_kind = WCO_RLS_INSERT_CHECK;

    /*
     * ExecWithCheckOptions() will skip any WCOs which are not of the kind
     * we are looking for at this point.
     */
    if (resultRelInfo->ri_WithCheckOptions != NIL)
      ExecWithCheckOptions(wco_kind, resultRelInfo, slot, estate);

    /*
     * Check the constraints of the tuple.
     */
    if (resultRelationDesc->rd_att->constr)
      ExecConstraints(resultRelInfo, slot, estate);

    /*
     * Also check the tuple against the partition constraint, if there is
     * one; except that if we got here via tuple-routing, we don't need to
     * if there's no BR trigger defined on the partition.
     */
    if (resultRelationDesc->rd_rel->relispartition &&
      (resultRelInfo->ri_RootResultRelInfo == NULL ||
       (resultRelInfo->ri_TrigDesc &&
        resultRelInfo->ri_TrigDesc->trig_insert_before_row)))
      ExecPartitionCheck(resultRelInfo, slot, estate, true);

    if (onconflict != ONCONFLICT_NONE && resultRelInfo->ri_NumIndices > 0)
    {
      /* Perform a speculative insertion. */
      uint32    specToken;
      ItemPointerData conflictTid;
      ItemPointerData invalidItemPtr;
      bool    specConflict;
      List     *arbiterIndexes;

      ItemPointerSetInvalid(&invalidItemPtr);
      arbiterIndexes = resultRelInfo->ri_onConflictArbiterIndexes;

      /*
       * Do a non-conclusive check for conflicts first.
       *
       * We're not holding any locks yet, so this doesn't guarantee that
       * the later insert won't conflict.  But it avoids leaving behind
       * a lot of canceled speculative insertions, if you run a lot of
       * INSERT ON CONFLICT statements that do conflict.
       *
       * We loop back here if we find a conflict below, either during
       * the pre-check, or when we re-check after inserting the tuple
       * speculatively.  Better allow interrupts in case some bug makes
       * this an infinite loop.
       */
  vlock:
      CHECK_FOR_INTERRUPTS();
      specConflict = false;
      if (!ExecCheckIndexConstraints(resultRelInfo, slot, estate,
                       &conflictTid, &invalidItemPtr,
                       arbiterIndexes))
      {
        /* committed conflict tuple found */
        if (onconflict == ONCONFLICT_UPDATE)
        {
          /*
           * In case of ON CONFLICT DO UPDATE, execute the UPDATE
           * part.  Be prepared to retry if the UPDATE fails because
           * of another concurrent UPDATE/DELETE to the conflict
           * tuple.
           */
          TupleTableSlot *returning = NULL;

          if (ExecOnConflictUpdate(context, resultRelInfo,
                       &conflictTid, slot, canSetTag,
                       &returning))
          {
            InstrCountTuples2(&mtstate->ps, 1);
            return returning;
          }
          else
            goto vlock;
        }
        else
        {
          /*
           * In case of ON CONFLICT DO NOTHING, do nothing. However,
           * verify that the tuple is visible to the executor's MVCC
           * snapshot at higher isolation levels.
           *
           * Using ExecGetReturningSlot() to store the tuple for the
           * recheck isn't that pretty, but we can't trivially use
           * the input slot, because it might not be of a compatible
           * type. As there's no conflicting usage of
           * ExecGetReturningSlot() in the DO NOTHING case...
           */
          Assert(onconflict == ONCONFLICT_NOTHING);
          ExecCheckTIDVisible(estate, resultRelInfo, &conflictTid,
                    ExecGetReturningSlot(estate, resultRelInfo));
          InstrCountTuples2(&mtstate->ps, 1);
          return NULL;
        }
      }

      /*
       * Before we start insertion proper, acquire our "speculative
       * insertion lock".  Others can use that to wait for us to decide
       * if we're going to go ahead with the insertion, instead of
       * waiting for the whole transaction to complete.
       */
      specToken = SpeculativeInsertionLockAcquire(GetCurrentTransactionId());

      /* insert the tuple, with the speculative token */
      table_tuple_insert_speculative(resultRelationDesc, slot,
                       estate->es_output_cid,
                       0,
                       NULL,
                       specToken);

      /* insert index entries for tuple */
      recheckIndexes = ExecInsertIndexTuples(resultRelInfo,
                           slot, estate, false, true,
                           &specConflict,
                           arbiterIndexes,
                           false);

      /* adjust the tuple's state accordingly */
      table_tuple_complete_speculative(resultRelationDesc, slot,
                       specToken, !specConflict);

      /*
       * Wake up anyone waiting for our decision.  They will re-check
       * the tuple, see that it's no longer speculative, and wait on our
       * XID as if this was a regularly inserted tuple all along.  Or if
       * we killed the tuple, they will see it's dead, and proceed as if
       * the tuple never existed.
       */
      SpeculativeInsertionLockRelease(GetCurrentTransactionId());

      /*
       * If there was a conflict, start from the beginning.  We'll do
       * the pre-check again, which will now find the conflicting tuple
       * (unless it aborts before we get there).
       */
      if (specConflict)
      {
        list_free(recheckIndexes);
        goto vlock;
      }

      /* Since there was no insertion conflict, we're done */
    }
    else
    {
      /* insert the tuple normally */
      table_tuple_insert(resultRelationDesc, slot,
                 estate->es_output_cid,
                 0, NULL);

      /* insert index entries for tuple */
      if (resultRelInfo->ri_NumIndices > 0)
        recheckIndexes = ExecInsertIndexTuples(resultRelInfo,
                             slot, estate, false,
                             false, NULL, NIL,
                             false);
    }
  }

  if (canSetTag)
    (estate->es_processed)++;

  /*
   * If this insert is the result of a partition key update that moved the
   * tuple to a new partition, put this row into the transition NEW TABLE,
   * if there is one. We need to do this separately for DELETE and INSERT
   * because they happen on different tables.
   */
  ar_insert_trig_tcs = mtstate->mt_transition_capture;
  if (mtstate->operation == CMD_UPDATE && mtstate->mt_transition_capture
    && mtstate->mt_transition_capture->tcs_update_new_table)
  {
    ExecARUpdateTriggers(estate, resultRelInfo,
               NULL, NULL,
               NULL,
               NULL,
               slot,
               NULL,
               mtstate->mt_transition_capture,
               false);

    /*
     * We've already captured the NEW TABLE row, so make sure any AR
     * INSERT trigger fired below doesn't capture it again.
     */
    ar_insert_trig_tcs = NULL;
  }

  /* AFTER ROW INSERT Triggers */
  ExecARInsertTriggers(estate, resultRelInfo, slot, recheckIndexes,
             ar_insert_trig_tcs);

  list_free(recheckIndexes);

  /*
   * Check any WITH CHECK OPTION constraints from parent views.  We are
   * required to do this after testing all constraints and uniqueness
   * violations per the SQL spec, so we do it after actually inserting the
   * record into the heap and all indexes.
   *
   * ExecWithCheckOptions will elog(ERROR) if a violation is found, so the
   * tuple will never be seen, if it violates the WITH CHECK OPTION.
   *
   * ExecWithCheckOptions() will skip any WCOs which are not of the kind we
   * are looking for at this point.
   */
  if (resultRelInfo->ri_WithCheckOptions != NIL)
    ExecWithCheckOptions(WCO_VIEW_CHECK, resultRelInfo, slot, estate);

  /* Process RETURNING if present */
  if (resultRelInfo->ri_projectReturning)
  {
    TupleTableSlot *oldSlot = NULL;

    /*
     * If this is part of a cross-partition UPDATE, and the RETURNING list
     * refers to any OLD columns, ExecDelete() will have saved the tuple
     * deleted from the original partition, which we must use here to
     * compute the OLD column values.  Otherwise, all OLD column values
     * will be NULL.
     */
    if (context->cpDeletedSlot)
    {
      TupleConversionMap *tupconv_map;

      /*
       * Convert the OLD tuple to the new partition's format/slot, if
       * needed.  Note that ExecDelete() already converted it to the
       * root's partition's format/slot.
       */
      oldSlot = context->cpDeletedSlot;
      tupconv_map = ExecGetRootToChildMap(resultRelInfo, estate);
      if (tupconv_map != NULL)
      {
        oldSlot = execute_attr_map_slot(tupconv_map->attrMap,
                        oldSlot,
                        ExecGetReturningSlot(estate,
                                   resultRelInfo));

        oldSlot->tts_tableOid = context->cpDeletedSlot->tts_tableOid;
        ItemPointerCopy(&context->cpDeletedSlot->tts_tid, &oldSlot->tts_tid);
      }
    }

    result = ExecProcessReturning(context, resultRelInfo, CMD_INSERT,
                    oldSlot, slot, planSlot);

    /*
     * For a cross-partition UPDATE, release the old tuple, first making
     * sure that the result slot has a local copy of any pass-by-reference
     * values.
     */
    if (context->cpDeletedSlot)
    {
      ExecMaterializeSlot(result);
      ExecClearTuple(oldSlot);
      if (context->cpDeletedSlot != oldSlot)
        ExecClearTuple(context->cpDeletedSlot);
      context->cpDeletedSlot = NULL;
    }
  }

  if (inserted_tuple)
    *inserted_tuple = slot;
  if (insert_destrel)
    *insert_destrel = resultRelInfo;

  return result;
}

/* ----------------------------------------------------------------
 *    ExecBatchInsert
 *
 *    Insert multiple tuples in an efficient way.
 *    Currently, this handles inserting into a foreign table without
 *    RETURNING clause.
 * ----------------------------------------------------------------
 */
static void
ExecBatchInsert(ModifyTableState *mtstate,
        ResultRelInfo *resultRelInfo,
        TupleTableSlot **slots,
        TupleTableSlot **planSlots,
        int numSlots,
        EState *estate,
        bool canSetTag)
{
  int     i;
  int     numInserted = numSlots;
  TupleTableSlot *slot = NULL;
  TupleTableSlot **rslots;

  /*
   * insert into foreign table: let the FDW do it
   */
  rslots = resultRelInfo->ri_FdwRoutine->ExecForeignBatchInsert(estate,
                                  resultRelInfo,
                                  slots,
                                  planSlots,
                                  &numInserted);

  for (i = 0; i < numInserted; i++)
  {
    slot = rslots[i];

    /*
     * AFTER ROW Triggers might reference the tableoid column, so
     * (re-)initialize tts_tableOid before evaluating them.
     */
    slot->tts_tableOid = RelationGetRelid(resultRelInfo->ri_RelationDesc);

    /* AFTER ROW INSERT Triggers */
    ExecARInsertTriggers(estate, resultRelInfo, slot, NIL,
               mtstate->mt_transition_capture);

    /*
     * Check any WITH CHECK OPTION constraints from parent views.  See the
     * comment in ExecInsert.
     */
    if (resultRelInfo->ri_WithCheckOptions != NIL)
      ExecWithCheckOptions(WCO_VIEW_CHECK, resultRelInfo, slot, estate);
  }

  if (canSetTag && numInserted > 0)
    estate->es_processed += numInserted;

  /* Clean up all the slots, ready for the next batch */
  for (i = 0; i < numSlots; i++)
  {
    ExecClearTuple(slots[i]);
    ExecClearTuple(planSlots[i]);
  }
  resultRelInfo->ri_NumSlots = 0;
}

/*
 * ExecPendingInserts -- flushes all pending inserts to the foreign tables
 */
static void
ExecPendingInserts(EState *estate)
{
  ListCell   *l1,
         *l2;

  forboth(l1, estate->es_insert_pending_result_relations,
      l2, estate->es_insert_pending_modifytables)
  {
    ResultRelInfo *resultRelInfo = (ResultRelInfo *) lfirst(l1);
    ModifyTableState *mtstate = (ModifyTableState *) lfirst(l2);

    Assert(mtstate);
    ExecBatchInsert(mtstate, resultRelInfo,
            resultRelInfo->ri_Slots,
            resultRelInfo->ri_PlanSlots,
            resultRelInfo->ri_NumSlots,
            estate, mtstate->canSetTag);
  }

  list_free(estate->es_insert_pending_result_relations);
  list_free(estate->es_insert_pending_modifytables);
  estate->es_insert_pending_result_relations = NIL;
  estate->es_insert_pending_modifytables = NIL;
}

/*
 * ExecDeletePrologue -- subroutine for ExecDelete
 *
 * Prepare executor state for DELETE.  Actually, the only thing we have to do
 * here is execute BEFORE ROW triggers.  We return false if one of them makes
 * the delete a no-op; otherwise, return true.
 */
static bool
ExecDeletePrologue(ModifyTableContext *context, ResultRelInfo *resultRelInfo,
           ItemPointer tupleid, HeapTuple oldtuple,
           TupleTableSlot **epqreturnslot, TM_Result *result)
{
  if (result)
    *result = TM_Ok;

  /* BEFORE ROW DELETE triggers */
  if (resultRelInfo->ri_TrigDesc &&
    resultRelInfo->ri_TrigDesc->trig_delete_before_row)
  {
    /* Flush any pending inserts, so rows are visible to the triggers */
    if (context->estate->es_insert_pending_result_relations != NIL)
      ExecPendingInserts(context->estate);

    return ExecBRDeleteTriggers(context->estate, context->epqstate,
                  resultRelInfo, tupleid, oldtuple,
                  epqreturnslot, result, &context->tmfd);
  }

  return true;
}

/*
 * ExecDeleteAct -- subroutine for ExecDelete
 *
 * Actually delete the tuple from a plain table.
 *
 * Caller is in charge of doing EvalPlanQual as necessary
 */
static TM_Result
ExecDeleteAct(ModifyTableContext *context, ResultRelInfo *resultRelInfo,
        ItemPointer tupleid, bool changingPart)
{
  EState     *estate = context->estate;

  return table_tuple_delete(resultRelInfo->ri_RelationDesc, tupleid,
                estate->es_output_cid,
                estate->es_snapshot,
                estate->es_crosscheck_snapshot,
                true /* wait for commit */ ,
                &context->tmfd,
                changingPart);
}

/*
 * ExecDeleteEpilogue -- subroutine for ExecDelete
 *
 * Closing steps of tuple deletion; this invokes AFTER FOR EACH ROW triggers,
 * including the UPDATE triggers if the deletion is being done as part of a
 * cross-partition tuple move.
 */
static void
ExecDeleteEpilogue(ModifyTableContext *context, ResultRelInfo *resultRelInfo,
           ItemPointer tupleid, HeapTuple oldtuple, bool changingPart)
{
  ModifyTableState *mtstate = context->mtstate;
  EState     *estate = context->estate;
  TransitionCaptureState *ar_delete_trig_tcs;

  /*
   * If this delete is the result of a partition key update that moved the
   * tuple to a new partition, put this row into the transition OLD TABLE,
   * if there is one. We need to do this separately for DELETE and INSERT
   * because they happen on different tables.
   */
  ar_delete_trig_tcs = mtstate->mt_transition_capture;
  if (mtstate->operation == CMD_UPDATE && mtstate->mt_transition_capture &&
    mtstate->mt_transition_capture->tcs_update_old_table)
  {
    ExecARUpdateTriggers(estate, resultRelInfo,
               NULL, NULL,
               tupleid, oldtuple,
               NULL, NULL, mtstate->mt_transition_capture,
               false);

    /*
     * We've already captured the OLD TABLE row, so make sure any AR
     * DELETE trigger fired below doesn't capture it again.
     */
    ar_delete_trig_tcs = NULL;
  }

  /* AFTER ROW DELETE Triggers */
  ExecARDeleteTriggers(estate, resultRelInfo, tupleid, oldtuple,
             ar_delete_trig_tcs, changingPart);
}

/* ----------------------------------------------------------------
 *    ExecDelete
 *
 *    DELETE is like UPDATE, except that we delete the tuple and no
 *    index modifications are needed.
 *
 *    When deleting from a table, tupleid identifies the tuple to delete and
 *    oldtuple is NULL.  When deleting through a view INSTEAD OF trigger,
 *    oldtuple is passed to the triggers and identifies what to delete, and
 *    tupleid is invalid.  When deleting from a foreign table, tupleid is
 *    invalid; the FDW has to figure out which row to delete using data from
 *    the planSlot.  oldtuple is passed to foreign table triggers; it is
 *    NULL when the foreign table has no relevant triggers.  We use
 *    tupleDeleted to indicate whether the tuple is actually deleted,
 *    callers can use it to decide whether to continue the operation.  When
 *    this DELETE is a part of an UPDATE of partition-key, then the slot
 *    returned by EvalPlanQual() is passed back using output parameter
 *    epqreturnslot.
 *
 *    Returns RETURNING result if any, otherwise NULL.
 * ----------------------------------------------------------------
 */
static TupleTableSlot *
ExecDelete(ModifyTableContext *context,
       ResultRelInfo *resultRelInfo,
       ItemPointer tupleid,
       HeapTuple oldtuple,
       bool processReturning,
       bool changingPart,
       bool canSetTag,
       TM_Result *tmresult,
       bool *tupleDeleted,
       TupleTableSlot **epqreturnslot)
{
  EState     *estate = context->estate;
  Relation  resultRelationDesc = resultRelInfo->ri_RelationDesc;
  TupleTableSlot *slot = NULL;
  TM_Result result;
  bool    saveOld;

  if (tupleDeleted)
    *tupleDeleted = false;

  /*
   * Prepare for the delete.  This includes BEFORE ROW triggers, so we're
   * done if it says we are.
   */
  if (!ExecDeletePrologue(context, resultRelInfo, tupleid, oldtuple,
              epqreturnslot, tmresult))
    return NULL;

  /* INSTEAD OF ROW DELETE Triggers */
  if (resultRelInfo->ri_TrigDesc &&
    resultRelInfo->ri_TrigDesc->trig_delete_instead_row)
  {
    bool    dodelete;

    Assert(oldtuple != NULL);
    dodelete = ExecIRDeleteTriggers(estate, resultRelInfo, oldtuple);

    if (!dodelete)     /* "do nothing" */
      return NULL;
  }
  else if (resultRelInfo->ri_FdwRoutine)
  {
    /*
     * delete from foreign table: let the FDW do it
     *
     * We offer the returning slot as a place to store RETURNING data,
     * although the FDW can return some other slot if it wants.
     */
    slot = ExecGetReturningSlot(estate, resultRelInfo);
    slot = resultRelInfo->ri_FdwRoutine->ExecForeignDelete(estate,
                                 resultRelInfo,
                                 slot,
                                 context->planSlot);

    if (slot == NULL)   /* "do nothing" */
      return NULL;

    /*
     * RETURNING expressions might reference the tableoid column, so
     * (re)initialize tts_tableOid before evaluating them.
     */
    if (TTS_EMPTY(slot))
      ExecStoreAllNullTuple(slot);

    slot->tts_tableOid = RelationGetRelid(resultRelationDesc);
  }
  else
  {
    /*
     * delete the tuple
     *
     * Note: if context->estate->es_crosscheck_snapshot isn't
     * InvalidSnapshot, we check that the row to be deleted is visible to
     * that snapshot, and throw a can't-serialize error if not. This is a
     * special-case behavior needed for referential integrity updates in
     * transaction-snapshot mode transactions.
     */
ldelete:
    result = ExecDeleteAct(context, resultRelInfo, tupleid, changingPart);

    if (tmresult)
      *tmresult = result;

    switch (result)
    {
      case TM_SelfModified:

        /*
         * The target tuple was already updated or deleted by the
         * current command, or by a later command in the current
         * transaction.  The former case is possible in a join DELETE
         * where multiple tuples join to the same target tuple. This
         * is somewhat questionable, but Postgres has always allowed
         * it: we just ignore additional deletion attempts.
         *
         * The latter case arises if the tuple is modified by a
         * command in a BEFORE trigger, or perhaps by a command in a
         * volatile function used in the query.  In such situations we
         * should not ignore the deletion, but it is equally unsafe to
         * proceed.  We don't want to discard the original DELETE
         * while keeping the triggered actions based on its deletion;
         * and it would be no better to allow the original DELETE
         * while discarding updates that it triggered.  The row update
         * carries some information that might be important according
         * to business rules; so throwing an error is the only safe
         * course.
         *
         * If a trigger actually intends this type of interaction, it
         * can re-execute the DELETE and then return NULL to cancel
         * the outer delete.
         */
        if (context->tmfd.cmax != estate->es_output_cid)
          ereport(ERROR,
              (errcode(ERRCODE_TRIGGERED_DATA_CHANGE_VIOLATION),
               errmsg("tuple to be deleted 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.")));

        /* Else, already deleted by self; nothing to do */
        return NULL;

      case TM_Ok:
        break;

      case TM_Updated:
        {
          TupleTableSlot *inputslot;
          TupleTableSlot *epqslot;

          if (IsolationUsesXactSnapshot())
            ereport(ERROR,
                (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                 errmsg("could not serialize access due to concurrent update")));

          /*
           * Already know that we're going to need to do EPQ, so
           * fetch tuple directly into the right slot.
           */
          EvalPlanQualBegin(context->epqstate);
          inputslot = EvalPlanQualSlot(context->epqstate, resultRelationDesc,
                         resultRelInfo->ri_RangeTableIndex);

          result = table_tuple_lock(resultRelationDesc, tupleid,
                        estate->es_snapshot,
                        inputslot, estate->es_output_cid,
                        LockTupleExclusive, LockWaitBlock,
                        TUPLE_LOCK_FLAG_FIND_LAST_VERSION,
                        &context->tmfd);

          switch (result)
          {
            case TM_Ok:
              Assert(context->tmfd.traversed);
              epqslot = EvalPlanQual(context->epqstate,
                           resultRelationDesc,
                           resultRelInfo->ri_RangeTableIndex,
                           inputslot);
              if (TupIsNull(epqslot))
                /* Tuple not passing quals anymore, exiting... */
                return NULL;

              /*
               * If requested, skip delete and pass back the
               * updated row.
               */
              if (epqreturnslot)
              {
                *epqreturnslot = epqslot;
                return NULL;
              }
              else
                goto ldelete;

            case TM_SelfModified:

              /*
               * This can be reached when following an update
               * chain from a tuple updated by another session,
               * reaching a tuple that was already updated in
               * this transaction. If previously updated by this
               * command, ignore the delete, otherwise error
               * out.
               *
               * See also TM_SelfModified response to
               * table_tuple_delete() above.
               */
              if (context->tmfd.cmax != estate->es_output_cid)
                ereport(ERROR,
                    (errcode(ERRCODE_TRIGGERED_DATA_CHANGE_VIOLATION),
                     errmsg("tuple to be deleted 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.")));
              return NULL;

            case TM_Deleted:
              /* tuple already deleted; nothing to do */
              return NULL;

            default:

              /*
               * TM_Invisible should be impossible because we're
               * waiting for updated row versions, and would
               * already have errored out if the first version
               * is invisible.
               *
               * TM_Updated should be impossible, because we're
               * locking the latest version via
               * TUPLE_LOCK_FLAG_FIND_LAST_VERSION.
               */
              elog(ERROR, "unexpected table_tuple_lock status: %u",
                 result);
              return NULL;
          }

          Assert(false);
          break;
        }

      case TM_Deleted:
        if (IsolationUsesXactSnapshot())
          ereport(ERROR,
              (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
               errmsg("could not serialize access due to concurrent delete")));
        /* tuple already deleted; nothing to do */
        return NULL;

      default:
        elog(ERROR, "unrecognized table_tuple_delete status: %u",
           result);
        return NULL;
    }

    /*
     * Note: Normally one would think that we have to delete index tuples
     * associated with the heap tuple now...
     *
     * ... but in POSTGRES, we have no need to do this because VACUUM will
     * take care of it later.  We can't delete index tuples immediately
     * anyway, since the tuple is still visible to other transactions.
     */
  }

  if (canSetTag)
    (estate->es_processed)++;

  /* Tell caller that the delete actually happened. */
  if (tupleDeleted)
    *tupleDeleted = true;

  ExecDeleteEpilogue(context, resultRelInfo, tupleid, oldtuple, changingPart);

  /*
   * Process RETURNING if present and if requested.
   *
   * If this is part of a cross-partition UPDATE, and the RETURNING list
   * refers to any OLD column values, save the old tuple here for later
   * processing of the RETURNING list by ExecInsert().
   */
  saveOld = changingPart && resultRelInfo->ri_projectReturning &&
    resultRelInfo->ri_projectReturning->pi_state.flags & EEO_FLAG_HAS_OLD;

  if (resultRelInfo->ri_projectReturning && (processReturning || saveOld))
  {
    /*
     * We have to put the target tuple into a slot, which means first we
     * gotta fetch it.  We can use the trigger tuple slot.
     */
    TupleTableSlot *rslot;

    if (resultRelInfo->ri_FdwRoutine)
    {
      /* FDW must have provided a slot containing the deleted row */
      Assert(!TupIsNull(slot));
    }
    else
    {
      slot = ExecGetReturningSlot(estate, resultRelInfo);
      if (oldtuple != NULL)
      {
        ExecForceStoreHeapTuple(oldtuple, slot, false);
      }
      else
      {
        if (!table_tuple_fetch_row_version(resultRelationDesc, tupleid,
                           SnapshotAny, slot))
          elog(ERROR, "failed to fetch deleted tuple for DELETE RETURNING");
      }
    }

    /*
     * If required, save the old tuple for later processing of the
     * RETURNING list by ExecInsert().
     */
    if (saveOld)
    {
      TupleConversionMap *tupconv_map;

      /*
       * Convert the tuple into the root partition's format/slot, if
       * needed.  ExecInsert() will then convert it to the new
       * partition's format/slot, if necessary.
       */
      tupconv_map = ExecGetChildToRootMap(resultRelInfo);
      if (tupconv_map != NULL)
      {
        ResultRelInfo *rootRelInfo = context->mtstate->rootResultRelInfo;
        TupleTableSlot *oldSlot = slot;

        slot = execute_attr_map_slot(tupconv_map->attrMap,
                       slot,
                       ExecGetReturningSlot(estate,
                                  rootRelInfo));

        slot->tts_tableOid = oldSlot->tts_tableOid;
        ItemPointerCopy(&oldSlot->tts_tid, &slot->tts_tid);
      }

      context->cpDeletedSlot = slot;

      return NULL;
    }

    rslot = ExecProcessReturning(context, resultRelInfo, CMD_DELETE,
                   slot, NULL, context->planSlot);

    /*
     * Before releasing the target tuple again, make sure rslot has a
     * local copy of any pass-by-reference values.
     */
    ExecMaterializeSlot(rslot);

    ExecClearTuple(slot);

    return rslot;
  }

  return NULL;
}

/*
 * ExecCrossPartitionUpdate --- Move an updated tuple to another partition.
 *
 * This works by first deleting the old tuple from the current partition,
 * followed by inserting the new tuple into the root parent table, that is,
 * mtstate->rootResultRelInfo.  It will be re-routed from there to the
 * correct partition.
 *
 * Returns true if the tuple has been successfully moved, or if it's found
 * that the tuple was concurrently deleted so there's nothing more to do
 * for the caller.
 *
 * False is returned if the tuple we're trying to move is found to have been
 * concurrently updated.  In that case, the caller must check if the updated
 * tuple that's returned in *retry_slot still needs to be re-routed, and call
 * this function again or perform a regular update accordingly.  For MERGE,
 * the updated tuple is not returned in *retry_slot; it has its own retry
 * logic.
 */
static bool
ExecCrossPartitionUpdate(ModifyTableContext *context,
             ResultRelInfo *resultRelInfo,
             ItemPointer tupleid, HeapTuple oldtuple,
             TupleTableSlot *slot,
             bool canSetTag,
             UpdateContext *updateCxt,
             TM_Result *tmresult,
             TupleTableSlot **retry_slot,
             TupleTableSlot **inserted_tuple,
             ResultRelInfo **insert_destrel)
{
  ModifyTableState *mtstate = context->mtstate;
  EState     *estate = mtstate->ps.state;
  TupleConversionMap *tupconv_map;
  bool    tuple_deleted;
  TupleTableSlot *epqslot = NULL;

  context->cpDeletedSlot = NULL;
  context->cpUpdateReturningSlot = NULL;
  *retry_slot = NULL;

  /*
   * Disallow an INSERT ON CONFLICT DO UPDATE that causes the original row
   * to migrate to a different partition.  Maybe this can be implemented
   * some day, but it seems a fringe feature with little redeeming value.
   */
  if (((ModifyTable *) mtstate->ps.plan)->onConflictAction == ONCONFLICT_UPDATE)
    ereport(ERROR,
        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
         errmsg("invalid ON UPDATE specification"),
         errdetail("The result tuple would appear in a different partition than the original tuple.")));

  /*
   * When an UPDATE is run directly on a leaf partition, simply fail with a
   * partition constraint violation error.
   */
  if (resultRelInfo == mtstate->rootResultRelInfo)
    ExecPartitionCheckEmitError(resultRelInfo, slot, estate);

  /* Initialize tuple routing info if not already done. */
  if (mtstate->mt_partition_tuple_routing == NULL)
  {
    Relation  rootRel = mtstate->rootResultRelInfo->ri_RelationDesc;
    MemoryContext oldcxt;

    /* Things built here have to last for the query duration. */
    oldcxt = MemoryContextSwitchTo(estate->es_query_cxt);

    mtstate->mt_partition_tuple_routing =
      ExecSetupPartitionTupleRouting(estate, rootRel);

    /*
     * Before a partition's tuple can be re-routed, it must first be
     * converted to the root's format, so we'll need a slot for storing
     * such tuples.
     */
    Assert(mtstate->mt_root_tuple_slot == NULL);
    mtstate->mt_root_tuple_slot = table_slot_create(rootRel, NULL);

    MemoryContextSwitchTo(oldcxt);
  }

  /*
   * Row movement, part 1.  Delete the tuple, but skip RETURNING processing.
   * We want to return rows from INSERT.
   */
  ExecDelete(context, resultRelInfo,
         tupleid, oldtuple,
         false,     /* processReturning */
         true,      /* changingPart */
         false,     /* canSetTag */
         tmresult, &tuple_deleted, &epqslot);

  /*
   * For some reason if DELETE didn't happen (e.g. trigger prevented it, or
   * it was already deleted by self, or it was concurrently deleted by
   * another transaction), then we should skip the insert as well;
   * otherwise, an UPDATE could cause an increase in the total number of
   * rows across all partitions, which is clearly wrong.
   *
   * For a normal UPDATE, the case where the tuple has been the subject of a
   * concurrent UPDATE or DELETE would be handled by the EvalPlanQual
   * machinery, but for an UPDATE that we've translated into a DELETE from
   * this partition and an INSERT into some other partition, that's not
   * available, because CTID chains can't span relation boundaries.  We
   * mimic the semantics to a limited extent by skipping the INSERT if the
   * DELETE fails to find a tuple.  This ensures that two concurrent
   * attempts to UPDATE the same tuple at the same time can't turn one tuple
   * into two, and that an UPDATE of a just-deleted tuple can't resurrect
   * it.
   */
  if (!tuple_deleted)
  {
    /*
     * epqslot will be typically NULL.  But when ExecDelete() finds that
     * another transaction has concurrently updated the same row, it
     * re-fetches the row, skips the delete, and epqslot is set to the
     * re-fetched tuple slot.  In that case, we need to do all the checks
     * again.  For MERGE, we leave everything to the caller (it must do
     * additional rechecking, and might end up executing a different
     * action entirely).
     */
    if (mtstate->operation == CMD_MERGE)
      return *tmresult == TM_Ok;
    else if (TupIsNull(epqslot))
      return true;
    else
    {
      /* Fetch the most recent version of old tuple. */
      TupleTableSlot *oldSlot;

      /* ... but first, make sure ri_oldTupleSlot is initialized. */
      if (unlikely(!resultRelInfo->ri_projectNewInfoValid))
        ExecInitUpdateProjection(mtstate, resultRelInfo);
      oldSlot = resultRelInfo->ri_oldTupleSlot;
      if (!table_tuple_fetch_row_version(resultRelInfo->ri_RelationDesc,
                         tupleid,
                         SnapshotAny,
                         oldSlot))
        elog(ERROR, "failed to fetch tuple being updated");
      /* and project the new tuple to retry the UPDATE with */
      *retry_slot = ExecGetUpdateNewTuple(resultRelInfo, epqslot,
                        oldSlot);
      return false;
    }
  }

  /*
   * resultRelInfo is one of the per-relation resultRelInfos.  So we should
   * convert the tuple into root's tuple descriptor if needed, since
   * ExecInsert() starts the search from root.
   */
  tupconv_map = ExecGetChildToRootMap(resultRelInfo);
  if (tupconv_map != NULL)
    slot = execute_attr_map_slot(tupconv_map->attrMap,
                   slot,
                   mtstate->mt_root_tuple_slot);

  /* Tuple routing starts from the root table. */
  context->cpUpdateReturningSlot =
    ExecInsert(context, mtstate->rootResultRelInfo, slot, canSetTag,
           inserted_tuple, insert_destrel);

  /*
   * Reset the transition state that may possibly have been written by
   * INSERT.
   */
  if (mtstate->mt_transition_capture)
    mtstate->mt_transition_capture->tcs_original_insert_tuple = NULL;

  /* We're done moving. */
  return true;
}

/*
 * ExecUpdatePrologue -- subroutine for ExecUpdate
 *
 * Prepare executor state for UPDATE.  This includes running BEFORE ROW
 * triggers.  We return false if one of them makes the update a no-op;
 * otherwise, return true.
 */
static bool
ExecUpdatePrologue(ModifyTableContext *context, ResultRelInfo *resultRelInfo,
           ItemPointer tupleid, HeapTuple oldtuple, TupleTableSlot *slot,
           TM_Result *result)
{
  Relation  resultRelationDesc = resultRelInfo->ri_RelationDesc;

  if (result)
    *result = TM_Ok;

  ExecMaterializeSlot(slot);

  /*
   * Open the table's indexes, if we have not done so already, so that we
   * can add new index entries for the updated tuple.
   */
  if (resultRelationDesc->rd_rel->relhasindex &&
    resultRelInfo->ri_IndexRelationDescs == NULL)
    ExecOpenIndices(resultRelInfo, false);

  /* BEFORE ROW UPDATE triggers */
  if (resultRelInfo->ri_TrigDesc &&
    resultRelInfo->ri_TrigDesc->trig_update_before_row)
  {
    /* Flush any pending inserts, so rows are visible to the triggers */
    if (context->estate->es_insert_pending_result_relations != NIL)
      ExecPendingInserts(context->estate);

    return ExecBRUpdateTriggers(context->estate, context->epqstate,
                  resultRelInfo, tupleid, oldtuple, slot,
                  result, &context->tmfd);
  }

  return true;
}

/*
 * ExecUpdatePrepareSlot -- subroutine for ExecUpdateAct
 *
 * Apply the final modifications to the tuple slot before the update.
 * (This is split out because we also need it in the foreign-table code path.)
 */
static void
ExecUpdatePrepareSlot(ResultRelInfo *resultRelInfo,
            TupleTableSlot *slot,
            EState *estate)
{
  Relation  resultRelationDesc = resultRelInfo->ri_RelationDesc;

  /*
   * Constraints and GENERATED expressions might reference the tableoid
   * column, so (re-)initialize tts_tableOid before evaluating them.
   */
  slot->tts_tableOid = RelationGetRelid(resultRelationDesc);

  /*
   * Compute stored generated columns
   */
  if (resultRelationDesc->rd_att->constr &&
    resultRelationDesc->rd_att->constr->has_generated_stored)
    ExecComputeStoredGenerated(resultRelInfo, estate, slot,
                   CMD_UPDATE);
}

/*
 * ExecUpdateAct -- subroutine for ExecUpdate
 *
 * Actually update the tuple, when operating on a plain table.  If the
 * table is a partition, and the command was called referencing an ancestor
 * partitioned table, this routine migrates the resulting tuple to another
 * partition.
 *
 * The caller is in charge of keeping indexes current as necessary.  The
 * caller is also in charge of doing EvalPlanQual if the tuple is found to
 * be concurrently updated.  However, in case of a cross-partition update,
 * this routine does it.
 */
static TM_Result
ExecUpdateAct(ModifyTableContext *context, ResultRelInfo *resultRelInfo,
        ItemPointer tupleid, HeapTuple oldtuple, TupleTableSlot *slot,
        bool canSetTag, UpdateContext *updateCxt)
{
  EState     *estate = context->estate;
  Relation  resultRelationDesc = resultRelInfo->ri_RelationDesc;
  bool    partition_constraint_failed;
  TM_Result result;

  updateCxt->crossPartUpdate = false;

  /*
   * If we move the tuple to a new partition, we loop back here to recompute
   * GENERATED values (which are allowed to be different across partitions)
   * and recheck any RLS policies and constraints.  We do not fire any
   * BEFORE triggers of the new partition, however.
   */
lreplace:
  /* Fill in GENERATEd columns */
  ExecUpdatePrepareSlot(resultRelInfo, slot, estate);

  /* ensure slot is independent, consider e.g. EPQ */
  ExecMaterializeSlot(slot);

  /*
   * If partition constraint fails, this row might get moved to another
   * partition, in which case we should check the RLS CHECK policy just
   * before inserting into the new partition, rather than doing it here.
   * This is because a trigger on that partition might again change the row.
   * So skip the WCO checks if the partition constraint fails.
   */
  partition_constraint_failed =
    resultRelationDesc->rd_rel->relispartition &&
    !ExecPartitionCheck(resultRelInfo, slot, estate, false);

  /* Check any RLS UPDATE WITH CHECK policies */
  if (!partition_constraint_failed &&
    resultRelInfo->ri_WithCheckOptions != NIL)
  {
    /*
     * ExecWithCheckOptions() will skip any WCOs which are not of the kind
     * we are looking for at this point.
     */
    ExecWithCheckOptions(WCO_RLS_UPDATE_CHECK,
               resultRelInfo, slot, estate);
  }

  /*
   * If a partition check failed, try to move the row into the right
   * partition.
   */
  if (partition_constraint_failed)
  {
    TupleTableSlot *inserted_tuple,
           *retry_slot;
    ResultRelInfo *insert_destrel = NULL;

    /*
     * ExecCrossPartitionUpdate will first DELETE the row from the
     * partition it's currently in and then insert it back into the root
     * table, which will re-route it to the correct partition.  However,
     * if the tuple has been concurrently updated, a retry is needed.
     */
    if (ExecCrossPartitionUpdate(context, resultRelInfo,
                   tupleid, oldtuple, slot,
                   canSetTag, updateCxt,
                   &result,
                   &retry_slot,
                   &inserted_tuple,
                   &insert_destrel))
    {
      /* success! */
      updateCxt->crossPartUpdate = true;

      /*
       * If the partitioned table being updated is referenced in foreign
       * keys, queue up trigger events to check that none of them were
       * violated.  No special treatment is needed in
       * non-cross-partition update situations, because the leaf
       * partition's AR update triggers will take care of that.  During
       * cross-partition updates implemented as delete on the source
       * partition followed by insert on the destination partition,
       * AR-UPDATE triggers of the root table (that is, the table
       * mentioned in the query) must be fired.
       *
       * NULL insert_destrel means that the move failed to occur, that
       * is, the update failed, so no need to anything in that case.
       */
      if (insert_destrel &&
        resultRelInfo->ri_TrigDesc &&
        resultRelInfo->ri_TrigDesc->trig_update_after_row)
        ExecCrossPartitionUpdateForeignKey(context,
                           resultRelInfo,
                           insert_destrel,
                           tupleid, slot,
                           inserted_tuple);

      return TM_Ok;
    }

    /*
     * No luck, a retry is needed.  If running MERGE, we do not do so
     * here; instead let it handle that on its own rules.
     */
    if (context->mtstate->operation == CMD_MERGE)
      return result;

    /*
     * ExecCrossPartitionUpdate installed an updated version of the new
     * tuple in the retry slot; start over.
     */
    slot = retry_slot;
    goto lreplace;
  }

  /*
   * Check the constraints of the tuple.  We've already checked the
   * partition constraint above; however, we must still ensure the tuple
   * passes all other constraints, so we will call ExecConstraints() and
   * have it validate all remaining checks.
   */
  if (resultRelationDesc->rd_att->constr)
    ExecConstraints(resultRelInfo, slot, estate);

  /*
   * replace the heap tuple
   *
   * Note: if es_crosscheck_snapshot isn't InvalidSnapshot, we check that
   * the row to be updated is visible to that snapshot, and throw a
   * can't-serialize error if not. This is a special-case behavior needed
   * for referential integrity updates in transaction-snapshot mode
   * transactions.
   */
  result = table_tuple_update(resultRelationDesc, tupleid, slot,
                estate->es_output_cid,
                estate->es_snapshot,
                estate->es_crosscheck_snapshot,
                true /* wait for commit */ ,
                &context->tmfd, &updateCxt->lockmode,
                &updateCxt->updateIndexes);

  return result;
}

/*
 * ExecUpdateEpilogue -- subroutine for ExecUpdate
 *
 * Closing steps of updating a tuple.  Must be called if ExecUpdateAct
 * returns indicating that the tuple was updated.
 */
static void
ExecUpdateEpilogue(ModifyTableContext *context, UpdateContext *updateCxt,
           ResultRelInfo *resultRelInfo, ItemPointer tupleid,
           HeapTuple oldtuple, TupleTableSlot *slot)
{
  ModifyTableState *mtstate = context->mtstate;
  List     *recheckIndexes = NIL;

  /* insert index entries for tuple if necessary */
  if (resultRelInfo->ri_NumIndices > 0 && (updateCxt->updateIndexes != TU_None))
    recheckIndexes = ExecInsertIndexTuples(resultRelInfo,
                         slot, context->estate,
                         true, false,
                         NULL, NIL,
                         (updateCxt->updateIndexes == TU_Summarizing));

  /* AFTER ROW UPDATE Triggers */
  ExecARUpdateTriggers(context->estate, resultRelInfo,
             NULL, NULL,
             tupleid, oldtuple, slot,
             recheckIndexes,
             mtstate->operation == CMD_INSERT ?
             mtstate->mt_oc_transition_capture :
             mtstate->mt_transition_capture,
             false);

  list_free(recheckIndexes);

  /*
   * Check any WITH CHECK OPTION constraints from parent views.  We are
   * required to do this after testing all constraints and uniqueness
   * violations per the SQL spec, so we do it after actually updating the
   * record in the heap and all indexes.
   *
   * ExecWithCheckOptions() will skip any WCOs which are not of the kind we
   * are looking for at this point.
   */
  if (resultRelInfo->ri_WithCheckOptions != NIL)
    ExecWithCheckOptions(WCO_VIEW_CHECK, resultRelInfo,
               slot, context->estate);
}

/*
 * Queues up an update event using the target root partitioned table's
 * trigger to check that a cross-partition update hasn't broken any foreign
 * keys pointing into it.
 */
static void
ExecCrossPartitionUpdateForeignKey(ModifyTableContext *context,
                   ResultRelInfo *sourcePartInfo,
                   ResultRelInfo *destPartInfo,
                   ItemPointer tupleid,
                   TupleTableSlot *oldslot,
                   TupleTableSlot *newslot)
{
  ListCell   *lc;
  ResultRelInfo *rootRelInfo;
  List     *ancestorRels;

  rootRelInfo = sourcePartInfo->ri_RootResultRelInfo;
  ancestorRels = ExecGetAncestorResultRels(context->estate, sourcePartInfo);

  /*
   * For any foreign keys that point directly into a non-root ancestors of
   * the source partition, we can in theory fire an update event to enforce
   * those constraints using their triggers, if we could tell that both the
   * source and the destination partitions are under the same ancestor. But
   * for now, we simply report an error that those cannot be enforced.
   */
  foreach(lc, ancestorRels)
  {
    ResultRelInfo *rInfo = lfirst(lc);
    TriggerDesc *trigdesc = rInfo->ri_TrigDesc;
    bool    has_noncloned_fkey = false;

    /* Root ancestor's triggers will be processed. */
    if (rInfo == rootRelInfo)
      continue;

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

        if (!trig->tgisclone &&
          RI_FKey_trigger_type(trig->tgfoid) == RI_TRIGGER_PK)
        {
          has_noncloned_fkey = true;
          break;
        }
      }
    }

    if (has_noncloned_fkey)
      ereport(ERROR,
          (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
           errmsg("cannot move tuple across partitions when a non-root ancestor of the source partition is directly referenced in a foreign key"),
           errdetail("A foreign key points to ancestor \"%s\" but not the root ancestor \"%s\".",
                 RelationGetRelationName(rInfo->ri_RelationDesc),
                 RelationGetRelationName(rootRelInfo->ri_RelationDesc)),
           errhint("Consider defining the foreign key on table \"%s\".",
               RelationGetRelationName(rootRelInfo->ri_RelationDesc))));
  }

  /* Perform the root table's triggers. */
  ExecARUpdateTriggers(context->estate,
             rootRelInfo, sourcePartInfo, destPartInfo,
             tupleid, NULL, newslot, NIL, NULL, true);
}

/* ----------------------------------------------------------------
 *    ExecUpdate
 *
 *    note: we can't run UPDATE queries with transactions
 *    off because UPDATEs are actually INSERTs and our
 *    scan will mistakenly loop forever, updating the tuple
 *    it just inserted..  This should be fixed but until it
 *    is, we don't want to get stuck in an infinite loop
 *    which corrupts your database..
 *
 *    When updating a table, tupleid identifies the tuple to update and
 *    oldtuple is NULL.  When updating through a view INSTEAD OF trigger,
 *    oldtuple is passed to the triggers and identifies what to update, and
 *    tupleid is invalid.  When updating a foreign table, tupleid is
 *    invalid; the FDW has to figure out which row to update using data from
 *    the planSlot.  oldtuple is passed to foreign table triggers; it is
 *    NULL when the foreign table has no relevant triggers.
 *
 *    oldSlot contains the old tuple value.
 *    slot contains the new tuple value to be stored.
 *    planSlot is the output of the ModifyTable's subplan; we use it
 *    to access values from other input tables (for RETURNING),
 *    row-ID junk columns, etc.
 *
 *    Returns RETURNING result if any, otherwise NULL.  On exit, if tupleid
 *    had identified the tuple to update, it will identify the tuple
 *    actually updated after EvalPlanQual.
 * ----------------------------------------------------------------
 */
static TupleTableSlot *
ExecUpdate(ModifyTableContext *context, ResultRelInfo *resultRelInfo,
       ItemPointer tupleid, HeapTuple oldtuple, TupleTableSlot *oldSlot,
       TupleTableSlot *slot, bool canSetTag)
{
  EState     *estate = context->estate;
  Relation  resultRelationDesc = resultRelInfo->ri_RelationDesc;
  UpdateContext updateCxt = {0};
  TM_Result result;

  /*
   * abort the operation if not running transactions
   */
  if (IsBootstrapProcessingMode())
    elog(ERROR, "cannot UPDATE during bootstrap");

  /*
   * Prepare for the update.  This includes BEFORE ROW triggers, so we're
   * done if it says we are.
   */
  if (!ExecUpdatePrologue(context, resultRelInfo, tupleid, oldtuple, slot, NULL))
    return NULL;

  /* INSTEAD OF ROW UPDATE Triggers */
  if (resultRelInfo->ri_TrigDesc &&
    resultRelInfo->ri_TrigDesc->trig_update_instead_row)
  {
    if (!ExecIRUpdateTriggers(estate, resultRelInfo,
                  oldtuple, slot))
      return NULL;   /* "do nothing" */
  }
  else if (resultRelInfo->ri_FdwRoutine)
  {
    /* Fill in GENERATEd columns */
    ExecUpdatePrepareSlot(resultRelInfo, slot, estate);

    /*
     * update in foreign table: let the FDW do it
     */
    slot = resultRelInfo->ri_FdwRoutine->ExecForeignUpdate(estate,
                                 resultRelInfo,
                                 slot,
                                 context->planSlot);

    if (slot == NULL)   /* "do nothing" */
      return NULL;

    /*
     * AFTER ROW Triggers or RETURNING expressions might reference the
     * tableoid column, so (re-)initialize tts_tableOid before evaluating
     * them.  (This covers the case where the FDW replaced the slot.)
     */
    slot->tts_tableOid = RelationGetRelid(resultRelationDesc);
  }
  else
  {
    ItemPointerData lockedtid;

    /*
     * If we generate a new candidate tuple after EvalPlanQual testing, we
     * must loop back here to try again.  (We don't need to redo triggers,
     * however.  If there are any BEFORE triggers then trigger.c will have
     * done table_tuple_lock to lock the correct tuple, so there's no need
     * to do them again.)
     */
redo_act:
    lockedtid = *tupleid;
    result = ExecUpdateAct(context, resultRelInfo, tupleid, oldtuple, slot,
                 canSetTag, &updateCxt);

    /*
     * If ExecUpdateAct reports that a cross-partition update was done,
     * then the RETURNING tuple (if any) has been projected and there's
     * nothing else for us to do.
     */
    if (updateCxt.crossPartUpdate)
      return context->cpUpdateReturningSlot;

    switch (result)
    {
      case TM_SelfModified:

        /*
         * The target tuple was already updated or deleted by the
         * current command, or by a later command in the current
         * transaction.  The former case is possible in a join UPDATE
         * where multiple tuples join to the same target tuple. This
         * is pretty questionable, but Postgres has always allowed it:
         * we just execute the first update action and ignore
         * additional update attempts.
         *
         * The latter case arises if the tuple is modified by a
         * command in a BEFORE trigger, or perhaps by a command in a
         * volatile function used in the query.  In such situations we
         * should not ignore the update, but it is equally unsafe to
         * proceed.  We don't want to discard the original UPDATE
         * while keeping the triggered actions based on it; and we
         * have no principled way to merge this update with the
         * previous ones.  So throwing an error is the only safe
         * course.
         *
         * If a trigger actually intends this type of interaction, it
         * can re-execute the UPDATE (assuming it can figure out how)
         * and then return NULL to cancel the outer update.
         */
        if (context->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.")));

        /* Else, already updated by self; nothing to do */
        return NULL;

      case TM_Ok:
        break;

      case TM_Updated:
        {
          TupleTableSlot *inputslot;
          TupleTableSlot *epqslot;

          if (IsolationUsesXactSnapshot())
            ereport(ERROR,
                (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                 errmsg("could not serialize access due to concurrent update")));

          /*
           * Already know that we're going to need to do EPQ, so
           * fetch tuple directly into the right slot.
           */
          inputslot = EvalPlanQualSlot(context->epqstate, resultRelationDesc,
                         resultRelInfo->ri_RangeTableIndex);

          result = table_tuple_lock(resultRelationDesc, tupleid,
                        estate->es_snapshot,
                        inputslot, estate->es_output_cid,
                        updateCxt.lockmode, LockWaitBlock,
                        TUPLE_LOCK_FLAG_FIND_LAST_VERSION,
                        &context->tmfd);

          switch (result)
          {
            case TM_Ok:
              Assert(context->tmfd.traversed);

              epqslot = EvalPlanQual(context->epqstate,
                           resultRelationDesc,
                           resultRelInfo->ri_RangeTableIndex,
                           inputslot);
              if (TupIsNull(epqslot))
                /* Tuple not passing quals anymore, exiting... */
                return NULL;

              /* Make sure ri_oldTupleSlot is initialized. */
              if (unlikely(!resultRelInfo->ri_projectNewInfoValid))
                ExecInitUpdateProjection(context->mtstate,
                             resultRelInfo);

              if (resultRelInfo->ri_needLockTagTuple)
              {
                UnlockTuple(resultRelationDesc,
                      &lockedtid, InplaceUpdateTupleLock);
                LockTuple(resultRelationDesc,
                      tupleid, InplaceUpdateTupleLock);
              }

              /* Fetch the most recent version of old tuple. */
              oldSlot = resultRelInfo->ri_oldTupleSlot;
              if (!table_tuple_fetch_row_version(resultRelationDesc,
                                 tupleid,
                                 SnapshotAny,
                                 oldSlot))
                elog(ERROR, "failed to fetch tuple being updated");
              slot = ExecGetUpdateNewTuple(resultRelInfo,
                             epqslot, oldSlot);
              goto redo_act;

            case TM_Deleted:
              /* tuple already deleted; nothing to do */
              return NULL;

            case TM_SelfModified:

              /*
               * This can be reached when following an update
               * chain from a tuple updated by another session,
               * reaching a tuple that was already updated in
               * this transaction. If previously modified by
               * this command, ignore the redundant update,
               * otherwise error out.
               *
               * See also TM_SelfModified response to
               * table_tuple_update() above.
               */
              if (context->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.")));
              return NULL;

            default:
              /* see table_tuple_lock call in ExecDelete() */
              elog(ERROR, "unexpected table_tuple_lock status: %u",
                 result);
              return NULL;
          }
        }

        break;

      case TM_Deleted:
        if (IsolationUsesXactSnapshot())
          ereport(ERROR,
              (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
               errmsg("could not serialize access due to concurrent delete")));
        /* tuple already deleted; nothing to do */
        return NULL;

      default:
        elog(ERROR, "unrecognized table_tuple_update status: %u",
           result);
        return NULL;
    }
  }

  if (canSetTag)
    (estate->es_processed)++;

  ExecUpdateEpilogue(context, &updateCxt, resultRelInfo, tupleid, oldtuple,
             slot);

  /* Process RETURNING if present */
  if (resultRelInfo->ri_projectReturning)
    return ExecProcessReturning(context, resultRelInfo, CMD_UPDATE,
                  oldSlot, slot, context->planSlot);

  return NULL;
}

/*
 * ExecOnConflictUpdate --- execute UPDATE of INSERT ON CONFLICT DO UPDATE
 *
 * Try to lock tuple for update as part of speculative insertion.  If
 * a qual originating from ON CONFLICT DO UPDATE is satisfied, update
 * (but still lock row, even though it may not satisfy estate's
 * snapshot).
 *
 * Returns true if we're done (with or without an update), or false if
 * the caller must retry the INSERT from scratch.
 */
static bool
ExecOnConflictUpdate(ModifyTableContext *context,
           ResultRelInfo *resultRelInfo,
           ItemPointer conflictTid,
           TupleTableSlot *excludedSlot,
           bool canSetTag,
           TupleTableSlot **returning)
{
  ModifyTableState *mtstate = context->mtstate;
  ExprContext *econtext = mtstate->ps.ps_ExprContext;
  Relation  relation = resultRelInfo->ri_RelationDesc;
  ExprState  *onConflictSetWhere = resultRelInfo->ri_onConflict->oc_WhereClause;
  TupleTableSlot *existing = resultRelInfo->ri_onConflict->oc_Existing;
  TM_FailureData tmfd;
  LockTupleMode lockmode;
  TM_Result test;
  Datum   xminDatum;
  TransactionId xmin;
  bool    isnull;

  /*
   * Parse analysis should have blocked ON CONFLICT for all system
   * relations, which includes these.  There's no fundamental obstacle to
   * supporting this; we'd just need to handle LOCKTAG_TUPLE like the other
   * ExecUpdate() caller.
   */
  Assert(!resultRelInfo->ri_needLockTagTuple);

  /* Determine lock mode to use */
  lockmode = ExecUpdateLockMode(context->estate, resultRelInfo);

  /*
   * Lock tuple for update.  Don't follow updates when tuple cannot be
   * locked without doing so.  A row locking conflict here means our
   * previous conclusion that the tuple is conclusively committed is not
   * true anymore.
   */
  test = table_tuple_lock(relation, conflictTid,
              context->estate->es_snapshot,
              existing, context->estate->es_output_cid,
              lockmode, LockWaitBlock, 0,
              &tmfd);
  switch (test)
  {
    case TM_Ok:
      /* success! */
      break;

    case TM_Invisible:

      /*
       * This can occur when a just inserted tuple is updated again in
       * the same command. E.g. because multiple rows with the same
       * conflicting key values are inserted.
       *
       * This is somewhat similar to the ExecUpdate() TM_SelfModified
       * case.  We do not want to proceed because it would lead to the
       * same row being updated a second time in some unspecified order,
       * and in contrast to plain UPDATEs there's no historical behavior
       * to break.
       *
       * It is the user's responsibility to prevent this situation from
       * occurring.  These problems are why the SQL standard similarly
       * specifies that for SQL MERGE, an exception must be raised in
       * the event of an attempt to update the same row twice.
       */
      xminDatum = slot_getsysattr(existing,
                    MinTransactionIdAttributeNumber,
                    &isnull);
      Assert(!isnull);
      xmin = DatumGetTransactionId(xminDatum);

      if (TransactionIdIsCurrentTransactionId(xmin))
        ereport(ERROR,
            (errcode(ERRCODE_CARDINALITY_VIOLATION),
        /* translator: %s is a SQL command name */
             errmsg("%s command cannot affect row a second time",
                "ON CONFLICT DO UPDATE"),
             errhint("Ensure that no rows proposed for insertion within the same command have duplicate constrained values.")));

      /* This shouldn't happen */
      elog(ERROR, "attempted to lock invisible tuple");
      break;

    case TM_SelfModified:

      /*
       * This state should never be reached. As a dirty snapshot is used
       * to find conflicting tuples, speculative insertion wouldn't have
       * seen this row to conflict with.
       */
      elog(ERROR, "unexpected self-updated tuple");
      break;

    case TM_Updated:
      if (IsolationUsesXactSnapshot())
        ereport(ERROR,
            (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
             errmsg("could not serialize access due to concurrent update")));

      /*
       * As long as we don't support an UPDATE of INSERT ON CONFLICT for
       * a partitioned table we shouldn't reach to a case where tuple to
       * be lock is moved to another partition due to concurrent update
       * of the partition key.
       */
      Assert(!ItemPointerIndicatesMovedPartitions(&tmfd.ctid));

      /*
       * Tell caller to try again from the very start.
       *
       * It does not make sense to use the usual EvalPlanQual() style
       * loop here, as the new version of the row might not conflict
       * anymore, or the conflicting tuple has actually been deleted.
       */
      ExecClearTuple(existing);
      return false;

    case TM_Deleted:
      if (IsolationUsesXactSnapshot())
        ereport(ERROR,
            (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
             errmsg("could not serialize access due to concurrent delete")));

      /* see TM_Updated case */
      Assert(!ItemPointerIndicatesMovedPartitions(&tmfd.ctid));
      ExecClearTuple(existing);
      return false;

    default:
      elog(ERROR, "unrecognized table_tuple_lock status: %u", test);
  }

  /* Success, the tuple is locked. */

  /*
   * Verify that the tuple is visible to our MVCC snapshot if the current
   * isolation level mandates that.
   *
   * It's not sufficient to rely on the check within ExecUpdate() as e.g.
   * CONFLICT ... WHERE clause may prevent us from reaching that.
   *
   * This means we only ever continue when a new command in the current
   * transaction could see the row, even though in READ COMMITTED mode the
   * tuple will not be visible according to the current statement's
   * snapshot.  This is in line with the way UPDATE deals with newer tuple
   * versions.
   */
  ExecCheckTupleVisible(context->estate, relation, existing);

  /*
   * Make tuple and any needed join variables available to ExecQual and
   * ExecProject.  The EXCLUDED tuple is installed in ecxt_innertuple, while
   * the target's existing tuple is installed in the scantuple.  EXCLUDED
   * has been made to reference INNER_VAR in setrefs.c, but there is no
   * other redirection.
   */
  econtext->ecxt_scantuple = existing;
  econtext->ecxt_innertuple = excludedSlot;
  econtext->ecxt_outertuple = NULL;

  if (!ExecQual(onConflictSetWhere, econtext))
  {
    ExecClearTuple(existing); /* see return below */
    InstrCountFiltered1(&mtstate->ps, 1);
    return true;      /* done with the tuple */
  }

  if (resultRelInfo->ri_WithCheckOptions != NIL)
  {
    /*
     * Check target's existing tuple against UPDATE-applicable USING
     * security barrier quals (if any), enforced here as RLS checks/WCOs.
     *
     * The rewriter creates UPDATE RLS checks/WCOs for UPDATE security
     * quals, and stores them as WCOs of "kind" WCO_RLS_CONFLICT_CHECK,
     * but that's almost the extent of its special handling for ON
     * CONFLICT DO UPDATE.
     *
     * The rewriter will also have associated UPDATE applicable straight
     * RLS checks/WCOs for the benefit of the ExecUpdate() call that
     * follows.  INSERTs and UPDATEs naturally have mutually exclusive WCO
     * kinds, so there is no danger of spurious over-enforcement in the
     * INSERT or UPDATE path.
     */
    ExecWithCheckOptions(WCO_RLS_CONFLICT_CHECK, resultRelInfo,
               existing,
               mtstate->ps.state);
  }

  /* Project the new tuple version */
  ExecProject(resultRelInfo->ri_onConflict->oc_ProjInfo);

  /*
   * Note that it is possible that the target tuple has been modified in
   * this session, after the above table_tuple_lock. We choose to not error
   * out in that case, in line with ExecUpdate's treatment of similar cases.
   * This can happen if an UPDATE is triggered from within ExecQual(),
   * ExecWithCheckOptions() or ExecProject() above, e.g. by selecting from a
   * wCTE in the ON CONFLICT's SET.
   */

  /* Execute UPDATE with projection */
  *returning = ExecUpdate(context, resultRelInfo,
              conflictTid, NULL, existing,
              resultRelInfo->ri_onConflict->oc_ProjSlot,
              canSetTag);

  /*
   * Clear out existing tuple, as there might not be another conflict among
   * the next input rows. Don't want to hold resources till the end of the
   * query.  First though, make sure that the returning slot, if any, has a
   * local copy of any OLD pass-by-reference values, if it refers to any OLD
   * columns.
   */
  if (*returning != NULL &&
    resultRelInfo->ri_projectReturning->pi_state.flags & EEO_FLAG_HAS_OLD)
    ExecMaterializeSlot(*returning);

  ExecClearTuple(existing);

  return true;
}

/*
 * Perform MERGE.
 */
static TupleTableSlot *
ExecMerge(ModifyTableContext *context, ResultRelInfo *resultRelInfo,
      ItemPointer tupleid, HeapTuple oldtuple, bool canSetTag)
{
  TupleTableSlot *rslot = NULL;
  bool    matched;

  /*-----
   * If we are dealing with a WHEN MATCHED case, tupleid or oldtuple is
   * valid, depending on whether the result relation is a table or a view.
   * We execute the first action for which the additional WHEN MATCHED AND
   * quals pass.  If an action without quals is found, that action is
   * executed.
   *
   * Similarly, in the WHEN NOT MATCHED BY SOURCE case, tupleid or oldtuple
   * is valid, and we look at the given WHEN NOT MATCHED BY SOURCE actions
   * in sequence until one passes.  This is almost identical to the WHEN
   * MATCHED case, and both cases are handled by ExecMergeMatched().
   *
   * Finally, in the WHEN NOT MATCHED [BY TARGET] case, both tupleid and
   * oldtuple are invalid, and we look at the given WHEN NOT MATCHED [BY
   * TARGET] actions in sequence until one passes.
   *
   * Things get interesting in case of concurrent update/delete of the
   * target tuple. Such concurrent update/delete is detected while we are
   * executing a WHEN MATCHED or WHEN NOT MATCHED BY SOURCE action.
   *
   * A concurrent update can:
   *
   * 1. modify the target tuple so that the results from checking any
   *    additional quals attached to WHEN MATCHED or WHEN NOT MATCHED BY
   *    SOURCE actions potentially change, but the result from the join
   *    quals does not change.
   *
   *    In this case, we are still dealing with the same kind of match
   *    (MATCHED or NOT MATCHED BY SOURCE).  We recheck the same list of
   *    actions from the start and choose the first one that satisfies the
   *    new target tuple.
   *
   * 2. modify the target tuple in the WHEN MATCHED case so that the join
   *    quals no longer pass and hence the source and target tuples no
   *    longer match.
   *
   *    In this case, we are now dealing with a NOT MATCHED case, and we
   *    process both WHEN NOT MATCHED BY SOURCE and WHEN NOT MATCHED [BY
   *    TARGET] actions.  First ExecMergeMatched() processes the list of
   *    WHEN NOT MATCHED BY SOURCE actions in sequence until one passes,
   *    then ExecMergeNotMatched() processes any WHEN NOT MATCHED [BY
   *    TARGET] actions in sequence until one passes.  Thus we may execute
   *    two actions; one of each kind.
   *
   * Thus we support concurrent updates that turn MATCHED candidate rows
   * into NOT MATCHED rows.  However, we do not attempt to support cases
   * that would turn NOT MATCHED rows into MATCHED rows, or which would
   * cause a target row to match a different source row.
   *
   * A concurrent delete changes a WHEN MATCHED case to WHEN NOT MATCHED
   * [BY TARGET].
   *
   * ExecMergeMatched() takes care of following the update chain and
   * re-finding the qualifying WHEN MATCHED or WHEN NOT MATCHED BY SOURCE
   * action, as long as the target tuple still exists. If the target tuple
   * gets deleted or a concurrent update causes the join quals to fail, it
   * returns a matched status of false and we call ExecMergeNotMatched().
   * Given that ExecMergeMatched() always makes progress by following the
   * update chain and we never switch from ExecMergeNotMatched() to
   * ExecMergeMatched(), there is no risk of a livelock.
   */
  matched = tupleid != NULL || oldtuple != NULL;
  if (matched)
    rslot = ExecMergeMatched(context, resultRelInfo, tupleid, oldtuple,
                 canSetTag, &matched);

  /*
   * Deal with the NOT MATCHED case (either a NOT MATCHED tuple from the
   * join, or a previously MATCHED tuple for which ExecMergeMatched() set
   * "matched" to false, indicating that it no longer matches).
   */
  if (!matched)
  {
    /*
     * If a concurrent update turned a MATCHED case into a NOT MATCHED
     * case, and we have both WHEN NOT MATCHED BY SOURCE and WHEN NOT
     * MATCHED [BY TARGET] actions, and there is a RETURNING clause,
     * ExecMergeMatched() may have already executed a WHEN NOT MATCHED BY
     * SOURCE action, and computed the row to return.  If so, we cannot
     * execute a WHEN NOT MATCHED [BY TARGET] action now, so mark it as
     * pending (to be processed on the next call to ExecModifyTable()).
     * Otherwise, just process the action now.
     */
    if (rslot == NULL)
      rslot = ExecMergeNotMatched(context, resultRelInfo, canSetTag);
    else
      context->mtstate->mt_merge_pending_not_matched = context->planSlot;
  }

  return rslot;
}

/*
 * Check and execute the first qualifying MATCHED or NOT MATCHED BY SOURCE
 * action, depending on whether the join quals are satisfied.  If the target
 * relation is a table, the current target tuple is identified by tupleid.
 * Otherwise, if the target relation is a view, oldtuple is the current target
 * tuple from the view.
 *
 * We start from the first WHEN MATCHED or WHEN NOT MATCHED BY SOURCE action
 * and check if the WHEN quals pass, if any. If the WHEN quals for the first
 * action do not pass, we check the second, then the third and so on. If we
 * reach the end without finding a qualifying action, we return NULL.
 * Otherwise, we execute the qualifying action and return its RETURNING
 * result, if any, or NULL.
 *
 * On entry, "*matched" is assumed to be true.  If a concurrent update or
 * delete is detected that causes the join quals to no longer pass, we set it
 * to false, indicating that the caller should process any NOT MATCHED [BY
 * TARGET] actions.
 *
 * After a concurrent update, we restart from the first action to look for a
 * new qualifying action to execute. If the join quals originally passed, and
 * the concurrent update caused them to no longer pass, then we switch from
 * the MATCHED to the NOT MATCHED BY SOURCE list of actions before restarting
 * (and setting "*matched" to false).  As a result we may execute a WHEN NOT
 * MATCHED BY SOURCE action, and set "*matched" to false, causing the caller
 * to also execute a WHEN NOT MATCHED [BY TARGET] action.
 */
static TupleTableSlot *
ExecMergeMatched(ModifyTableContext *context, ResultRelInfo *resultRelInfo,
         ItemPointer tupleid, HeapTuple oldtuple, bool canSetTag,
         bool *matched)
{
  ModifyTableState *mtstate = context->mtstate;
  List    **mergeActions = resultRelInfo->ri_MergeActions;
  ItemPointerData lockedtid;
  List     *actionStates;
  TupleTableSlot *newslot = NULL;
  TupleTableSlot *rslot = NULL;
  EState     *estate = context->estate;
  ExprContext *econtext = mtstate->ps.ps_ExprContext;
  bool    isNull;
  EPQState   *epqstate = &mtstate->mt_epqstate;
  ListCell   *l;

  /* Expect matched to be true on entry */
  Assert(*matched);

  /*
   * If there are no WHEN MATCHED or WHEN NOT MATCHED BY SOURCE actions, we
   * are done.
   */
  if (mergeActions[MERGE_WHEN_MATCHED] == NIL &&
    mergeActions[MERGE_WHEN_NOT_MATCHED_BY_SOURCE] == NIL)
    return NULL;

  /*
   * Make tuple and any needed join variables available to ExecQual and
   * ExecProject. The target's existing tuple is installed in the scantuple.
   * This target relation's slot is required only in the case of a MATCHED
   * or NOT MATCHED BY SOURCE tuple and UPDATE/DELETE actions.
   */
  econtext->ecxt_scantuple = resultRelInfo->ri_oldTupleSlot;
  econtext->ecxt_innertuple = context->planSlot;
  econtext->ecxt_outertuple = NULL;

  /*
   * This routine is only invoked for matched target rows, so we should
   * either have the tupleid of the target row, or an old tuple from the
   * target wholerow junk attr.
   */
  Assert(tupleid != NULL || oldtuple != NULL);
  ItemPointerSetInvalid(&lockedtid);
  if (oldtuple != NULL)
  {
    Assert(!resultRelInfo->ri_needLockTagTuple);
    ExecForceStoreHeapTuple(oldtuple, resultRelInfo->ri_oldTupleSlot,
                false);
  }
  else
  {
    if (resultRelInfo->ri_needLockTagTuple)
    {
      /*
       * This locks even for CMD_DELETE, for CMD_NOTHING, and for tuples
       * that don't match mas_whenqual.  MERGE on system catalogs is a
       * minor use case, so don't bother optimizing those.
       */
      LockTuple(resultRelInfo->ri_RelationDesc, tupleid,
            InplaceUpdateTupleLock);
      lockedtid = *tupleid;
    }
    if (!table_tuple_fetch_row_version(resultRelInfo->ri_RelationDesc,
                       tupleid,
                       SnapshotAny,
                       resultRelInfo->ri_oldTupleSlot))
      elog(ERROR, "failed to fetch the target tuple");
  }

  /*
   * Test the join condition.  If it's satisfied, perform a MATCHED action.
   * Otherwise, perform a NOT MATCHED BY SOURCE action.
   *
   * Note that this join condition will be NULL if there are no NOT MATCHED
   * BY SOURCE actions --- see transform_MERGE_to_join().  In that case, we
   * need only consider MATCHED actions here.
   */
  if (ExecQual(resultRelInfo->ri_MergeJoinCondition, econtext))
    actionStates = mergeActions[MERGE_WHEN_MATCHED];
  else
    actionStates = mergeActions[MERGE_WHEN_NOT_MATCHED_BY_SOURCE];

lmerge_matched:

  foreach(l, actionStates)
  {
    MergeActionState *relaction = (MergeActionState *) lfirst(l);
    CmdType   commandType = relaction->mas_action->commandType;
    TM_Result result;
    UpdateContext updateCxt = {0};

    /*
     * Test condition, if any.
     *
     * In the absence of any condition, we perform the action
     * unconditionally (no need to check separately since ExecQual() will
     * return true if there are no conditions to evaluate).
     */
    if (!ExecQual(relaction->mas_whenqual, econtext))
      continue;

    /*
     * Check if the existing target tuple meets the USING checks of
     * UPDATE/DELETE RLS policies. If those checks fail, we throw an
     * error.
     *
     * The WITH CHECK quals for UPDATE RLS policies are applied in
     * ExecUpdateAct() and hence we need not do anything special to handle
     * them.
     *
     * NOTE: We must do this after WHEN quals are evaluated, so that we
     * check policies only when they matter.
     */
    if (resultRelInfo->ri_WithCheckOptions && commandType != CMD_NOTHING)
    {
      ExecWithCheckOptions(commandType == CMD_UPDATE ?
                 WCO_RLS_MERGE_UPDATE_CHECK : WCO_RLS_MERGE_DELETE_CHECK,
                 resultRelInfo,
                 resultRelInfo->ri_oldTupleSlot,
                 context->mtstate->ps.state);
    }

    /* Perform stated action */
    switch (commandType)
    {
      case CMD_UPDATE:

        /*
         * Project the output tuple, and use that to update the table.
         * We don't need to filter out junk attributes, because the
         * UPDATE action's targetlist doesn't have any.
         */
        newslot = ExecProject(relaction->mas_proj);

        mtstate->mt_merge_action = relaction;
        if (!ExecUpdatePrologue(context, resultRelInfo,
                    tupleid, NULL, newslot, &result))
        {
          if (result == TM_Ok)
            goto out; /* "do nothing" */

          break;   /* concurrent update/delete */
        }

        /* INSTEAD OF ROW UPDATE Triggers */
        if (resultRelInfo->ri_TrigDesc &&
          resultRelInfo->ri_TrigDesc->trig_update_instead_row)
        {
          if (!ExecIRUpdateTriggers(estate, resultRelInfo,
                        oldtuple, newslot))
            goto out; /* "do nothing" */
        }
        else
        {
          /* checked ri_needLockTagTuple above */
          Assert(oldtuple == NULL);

          result = ExecUpdateAct(context, resultRelInfo, tupleid,
                       NULL, newslot, canSetTag,
                       &updateCxt);

          /*
           * As in ExecUpdate(), if ExecUpdateAct() reports that a
           * cross-partition update was done, then there's nothing
           * else for us to do --- the UPDATE has been turned into a
           * DELETE and an INSERT, and we must not perform any of
           * the usual post-update tasks.  Also, the RETURNING tuple
           * (if any) has been projected, so we can just return
           * that.
           */
          if (updateCxt.crossPartUpdate)
          {
            mtstate->mt_merge_updated += 1;
            rslot = context->cpUpdateReturningSlot;
            goto out;
          }
        }

        if (result == TM_Ok)
        {
          ExecUpdateEpilogue(context, &updateCxt, resultRelInfo,
                     tupleid, NULL, newslot);
          mtstate->mt_merge_updated += 1;
        }
        break;

      case CMD_DELETE:
        mtstate->mt_merge_action = relaction;
        if (!ExecDeletePrologue(context, resultRelInfo, tupleid,
                    NULL, NULL, &result))
        {
          if (result == TM_Ok)
            goto out; /* "do nothing" */

          break;   /* concurrent update/delete */
        }

        /* INSTEAD OF ROW DELETE Triggers */
        if (resultRelInfo->ri_TrigDesc &&
          resultRelInfo->ri_TrigDesc->trig_delete_instead_row)
        {
          if (!ExecIRDeleteTriggers(estate, resultRelInfo,
                        oldtuple))
            goto out; /* "do nothing" */
        }
        else
        {
          /* checked ri_needLockTagTuple above */
          Assert(oldtuple == NULL);

          result = ExecDeleteAct(context, resultRelInfo, tupleid,
                       false);
        }

        if (result == TM_Ok)
        {
          ExecDeleteEpilogue(context, resultRelInfo, tupleid, NULL,
                     false);
          mtstate->mt_merge_deleted += 1;
        }
        break;

      case CMD_NOTHING:
        /* Doing nothing is always OK */
        result = TM_Ok;
        break;

      default:
        elog(ERROR, "unknown action in MERGE WHEN clause");
    }

    switch (result)
    {
      case TM_Ok:
        /* all good; perform final actions */
        if (canSetTag && commandType != CMD_NOTHING)
          (estate->es_processed)++;

        break;

      case TM_SelfModified:

        /*
         * The target tuple was already updated or deleted by the
         * current command, or by a later command in the current
         * transaction.  The former case is explicitly disallowed by
         * the SQL standard for MERGE, which insists that the MERGE
         * join condition should not join a target row to more than
         * one source row.
         *
         * The latter case arises if the tuple is modified by a
         * command in a BEFORE trigger, or perhaps by a command in a
         * volatile function used in the query.  In such situations we
         * should not ignore the MERGE action, but it is equally
         * unsafe to proceed.  We don't want to discard the original
         * MERGE action while keeping the triggered actions based on
         * it; and it would be no better to allow the original MERGE
         * action while discarding the updates that it triggered.  So
         * throwing an error is the only safe course.
         */
        if (context->tmfd.cmax != estate->es_output_cid)
          ereport(ERROR,
              (errcode(ERRCODE_TRIGGERED_DATA_CHANGE_VIOLATION),
               errmsg("tuple to be updated or deleted 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.")));

        if (TransactionIdIsCurrentTransactionId(context->tmfd.xmax))
          ereport(ERROR,
              (errcode(ERRCODE_CARDINALITY_VIOLATION),
          /* translator: %s is a SQL command name */
               errmsg("%s command cannot affect row a second time",
                  "MERGE"),
               errhint("Ensure that not more than one source row matches any one target row.")));

        /* This shouldn't happen */
        elog(ERROR, "attempted to update or delete invisible tuple");
        break;

      case TM_Deleted:
        if (IsolationUsesXactSnapshot())
          ereport(ERROR,
              (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
               errmsg("could not serialize access due to concurrent delete")));

        /*
         * If the tuple was already deleted, set matched to false to
         * let caller handle it under NOT MATCHED [BY TARGET] clauses.
         */
        *matched = false;
        goto out;

      case TM_Updated:
        {
          bool    was_matched;
          Relation  resultRelationDesc;
          TupleTableSlot *epqslot,
                 *inputslot;
          LockTupleMode lockmode;

          /*
           * The target tuple was concurrently updated by some other
           * transaction.  If we are currently processing a MATCHED
           * action, use EvalPlanQual() with the new version of the
           * tuple and recheck the join qual, to detect a change
           * from the MATCHED to the NOT MATCHED cases.  If we are
           * already processing a NOT MATCHED BY SOURCE action, we
           * skip this (cannot switch from NOT MATCHED BY SOURCE to
           * MATCHED).
           */
          was_matched = relaction->mas_action->matchKind == MERGE_WHEN_MATCHED;
          resultRelationDesc = resultRelInfo->ri_RelationDesc;
          lockmode = ExecUpdateLockMode(estate, resultRelInfo);

          if (was_matched)
            inputslot = EvalPlanQualSlot(epqstate, resultRelationDesc,
                           resultRelInfo->ri_RangeTableIndex);
          else
            inputslot = resultRelInfo->ri_oldTupleSlot;

          result = table_tuple_lock(resultRelationDesc, tupleid,
                        estate->es_snapshot,
                        inputslot, estate->es_output_cid,
                        lockmode, LockWaitBlock,
                        TUPLE_LOCK_FLAG_FIND_LAST_VERSION,
                        &context->tmfd);
          switch (result)
          {
            case TM_Ok:

              /*
               * If the tuple was updated and migrated to
               * another partition concurrently, the current
               * MERGE implementation can't follow.  There's
               * probably a better way to handle this case, but
               * it'd require recognizing the relation to which
               * the tuple moved, and setting our current
               * resultRelInfo to that.
               */
              if (ItemPointerIndicatesMovedPartitions(&context->tmfd.ctid))
                ereport(ERROR,
                    (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
                     errmsg("tuple to be merged was already moved to another partition due to concurrent update")));

              /*
               * If this was a MATCHED case, use EvalPlanQual()
               * to recheck the join condition.
               */
              if (was_matched)
              {
                epqslot = EvalPlanQual(epqstate,
                             resultRelationDesc,
                             resultRelInfo->ri_RangeTableIndex,
                             inputslot);

                /*
                 * If the subplan didn't return a tuple, then
                 * we must be dealing with an inner join for
                 * which the join condition no longer matches.
                 * This can only happen if there are no NOT
                 * MATCHED actions, and so there is nothing
                 * more to do.
                 */
                if (TupIsNull(epqslot))
                  goto out;

                /*
                 * If we got a NULL ctid from the subplan, the
                 * join quals no longer pass and we switch to
                 * the NOT MATCHED BY SOURCE case.
                 */
                (void) ExecGetJunkAttribute(epqslot,
                              resultRelInfo->ri_RowIdAttNo,
                              &isNull);
                if (isNull)
                  *matched = false;

                /*
                 * Otherwise, recheck the join quals to see if
                 * we need to switch to the NOT MATCHED BY
                 * SOURCE case.
                 */
                if (resultRelInfo->ri_needLockTagTuple)
                {
                  if (ItemPointerIsValid(&lockedtid))
                    UnlockTuple(resultRelInfo->ri_RelationDesc, &lockedtid,
                          InplaceUpdateTupleLock);
                  LockTuple(resultRelInfo->ri_RelationDesc, &context->tmfd.ctid,
                        InplaceUpdateTupleLock);
                  lockedtid = context->tmfd.ctid;
                }
                if (!table_tuple_fetch_row_version(resultRelationDesc,
                                   &context->tmfd.ctid,
                                   SnapshotAny,
                                   resultRelInfo->ri_oldTupleSlot))
                  elog(ERROR, "failed to fetch the target tuple");

                if (*matched)
                  *matched = ExecQual(resultRelInfo->ri_MergeJoinCondition,
                            econtext);

                /* Switch lists, if necessary */
                if (!*matched)
                  actionStates = mergeActions[MERGE_WHEN_NOT_MATCHED_BY_SOURCE];
              }

              /*
               * Loop back and process the MATCHED or NOT
               * MATCHED BY SOURCE actions from the start.
               */
              goto lmerge_matched;

            case TM_Deleted:

              /*
               * tuple already deleted; tell caller to run NOT
               * MATCHED [BY TARGET] actions
               */
              *matched = false;
              goto out;

            case TM_SelfModified:

              /*
               * This can be reached when following an update
               * chain from a tuple updated by another session,
               * reaching a tuple that was already updated or
               * deleted by the current command, or by a later
               * command in the current transaction. As above,
               * this should always be treated as an error.
               */
              if (context->tmfd.cmax != estate->es_output_cid)
                ereport(ERROR,
                    (errcode(ERRCODE_TRIGGERED_DATA_CHANGE_VIOLATION),
                     errmsg("tuple to be updated or deleted 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.")));

              if (TransactionIdIsCurrentTransactionId(context->tmfd.xmax))
                ereport(ERROR,
                    (errcode(ERRCODE_CARDINALITY_VIOLATION),
                /* translator: %s is a SQL command name */
                     errmsg("%s command cannot affect row a second time",
                        "MERGE"),
                     errhint("Ensure that not more than one source row matches any one target row.")));

              /* This shouldn't happen */
              elog(ERROR, "attempted to update or delete invisible tuple");
              goto out;

            default:
              /* see table_tuple_lock call in ExecDelete() */
              elog(ERROR, "unexpected table_tuple_lock status: %u",
                 result);
              goto out;
          }
        }

      case TM_Invisible:
      case TM_WouldBlock:
      case TM_BeingModified:
        /* these should not occur */
        elog(ERROR, "unexpected tuple operation result: %d", result);
        break;
    }

    /* Process RETURNING if present */
    if (resultRelInfo->ri_projectReturning)
    {
      switch (commandType)
      {
        case CMD_UPDATE:
          rslot = ExecProcessReturning(context,
                         resultRelInfo,
                         CMD_UPDATE,
                         resultRelInfo->ri_oldTupleSlot,
                         newslot,
                         context->planSlot);
          break;

        case CMD_DELETE:
          rslot = ExecProcessReturning(context,
                         resultRelInfo,
                         CMD_DELETE,
                         resultRelInfo->ri_oldTupleSlot,
                         NULL,
                         context->planSlot);
          break;

        case CMD_NOTHING:
          break;

        default:
          elog(ERROR, "unrecognized commandType: %d",
             (int) commandType);
      }
    }

    /*
     * We've activated one of the WHEN clauses, so we don't search
     * further. This is required behaviour, not an optimization.
     */
    break;
  }

  /*
   * Successfully executed an action or no qualifying action was found.
   */
out:
  if (ItemPointerIsValid(&lockedtid))
    UnlockTuple(resultRelInfo->ri_RelationDesc, &lockedtid,
          InplaceUpdateTupleLock);
  return rslot;
}

/*
 * Execute the first qualifying NOT MATCHED [BY TARGET] action.
 */
static TupleTableSlot *
ExecMergeNotMatched(ModifyTableContext *context, ResultRelInfo *resultRelInfo,
          bool canSetTag)
{
  ModifyTableState *mtstate = context->mtstate;
  ExprContext *econtext = mtstate->ps.ps_ExprContext;
  List     *actionStates;
  TupleTableSlot *rslot = NULL;
  ListCell   *l;

  /*
   * For INSERT actions, the root relation's merge action is OK since the
   * INSERT's targetlist and the WHEN conditions can only refer to the
   * source relation and hence it does not matter which result relation we
   * work with.
   *
   * XXX does this mean that we can avoid creating copies of actionStates on
   * partitioned tables, for not-matched actions?
   */
  actionStates = resultRelInfo->ri_MergeActions[MERGE_WHEN_NOT_MATCHED_BY_TARGET];

  /*
   * Make source tuple available to ExecQual and ExecProject. We don't need
   * the target tuple, since the WHEN quals and targetlist can't refer to
   * the target columns.
   */
  econtext->ecxt_scantuple = NULL;
  econtext->ecxt_innertuple = context->planSlot;
  econtext->ecxt_outertuple = NULL;

  foreach(l, actionStates)
  {
    MergeActionState *action = (MergeActionState *) lfirst(l);
    CmdType   commandType = action->mas_action->commandType;
    TupleTableSlot *newslot;

    /*
     * Test condition, if any.
     *
     * In the absence of any condition, we perform the action
     * unconditionally (no need to check separately since ExecQual() will
     * return true if there are no conditions to evaluate).
     */
    if (!ExecQual(action->mas_whenqual, econtext))
      continue;

    /* Perform stated action */
    switch (commandType)
    {
      case CMD_INSERT:

        /*
         * Project the tuple.  In case of a partitioned table, the
         * projection was already built to use the root's descriptor,
         * so we don't need to map the tuple here.
         */
        newslot = ExecProject(action->mas_proj);
        mtstate->mt_merge_action = action;

        rslot = ExecInsert(context, mtstate->rootResultRelInfo,
                   newslot, canSetTag, NULL, NULL);
        mtstate->mt_merge_inserted += 1;
        break;
      case CMD_NOTHING:
        /* Do nothing */
        break;
      default:
        elog(ERROR, "unknown action in MERGE WHEN NOT MATCHED clause");
    }

    /*
     * We've activated one of the WHEN clauses, so we don't search
     * further. This is required behaviour, not an optimization.
     */
    break;
  }

  return rslot;
}

/*
 * Initialize state for execution of MERGE.
 */
void
ExecInitMerge(ModifyTableState *mtstate, EState *estate)
{
  List     *mergeActionLists = mtstate->mt_mergeActionLists;
  List     *mergeJoinConditions = mtstate->mt_mergeJoinConditions;
  ResultRelInfo *rootRelInfo = mtstate->rootResultRelInfo;
  ResultRelInfo *resultRelInfo;
  ExprContext *econtext;
  ListCell   *lc;
  int     i;

  if (mergeActionLists == NIL)
    return;

  mtstate->mt_merge_subcommands = 0;

  if (mtstate->ps.ps_ExprContext == NULL)
    ExecAssignExprContext(estate, &mtstate->ps);
  econtext = mtstate->ps.ps_ExprContext;

  /*
   * Create a MergeActionState for each action on the mergeActionList and
   * add it to either a list of matched actions or not-matched actions.
   *
   * Similar logic appears in ExecInitPartitionInfo(), so if changing
   * anything here, do so there too.
   */
  i = 0;
  foreach(lc, mergeActionLists)
  {
    List     *mergeActionList = lfirst(lc);
    Node     *joinCondition;
    TupleDesc relationDesc;
    ListCell   *l;

    joinCondition = (Node *) list_nth(mergeJoinConditions, i);
    resultRelInfo = mtstate->resultRelInfo + i;
    i++;
    relationDesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);

    /* initialize slots for MERGE fetches from this rel */
    if (unlikely(!resultRelInfo->ri_projectNewInfoValid))
      ExecInitMergeTupleSlots(mtstate, resultRelInfo);

    /* initialize state for join condition checking */
    resultRelInfo->ri_MergeJoinCondition =
      ExecInitQual((List *) joinCondition, &mtstate->ps);

    foreach(l, mergeActionList)
    {
      MergeAction *action = (MergeAction *) lfirst(l);
      MergeActionState *action_state;
      TupleTableSlot *tgtslot;
      TupleDesc tgtdesc;

      /*
       * Build action merge state for this rel.  (For partitions,
       * equivalent code exists in ExecInitPartitionInfo.)
       */
      action_state = makeNode(MergeActionState);
      action_state->mas_action = action;
      action_state->mas_whenqual = ExecInitQual((List *) action->qual,
                            &mtstate->ps);

      /*
       * We create three lists - one for each MergeMatchKind - and stick
       * the MergeActionState into the appropriate list.
       */
      resultRelInfo->ri_MergeActions[action->matchKind] =
        lappend(resultRelInfo->ri_MergeActions[action->matchKind],
            action_state);

      switch (action->commandType)
      {
        case CMD_INSERT:
          /* INSERT actions always use rootRelInfo */
          ExecCheckPlanOutput(rootRelInfo->ri_RelationDesc,
                    action->targetList);

          /*
           * If the MERGE targets a partitioned table, any INSERT
           * actions must be routed through it, not the child
           * relations. Initialize the routing struct and the root
           * table's "new" tuple slot for that, if not already done.
           * The projection we prepare, for all relations, uses the
           * root relation descriptor, and targets the plan's root
           * slot.  (This is consistent with the fact that we
           * checked the plan output to match the root relation,
           * above.)
           */
          if (rootRelInfo->ri_RelationDesc->rd_rel->relkind ==
            RELKIND_PARTITIONED_TABLE)
          {
            if (mtstate->mt_partition_tuple_routing == NULL)
            {
              /*
               * Initialize planstate for routing if not already
               * done.
               *
               * Note that the slot is managed as a standalone
               * slot belonging to ModifyTableState, so we pass
               * NULL for the 2nd argument.
               */
              mtstate->mt_root_tuple_slot =
                table_slot_create(rootRelInfo->ri_RelationDesc,
                          NULL);
              mtstate->mt_partition_tuple_routing =
                ExecSetupPartitionTupleRouting(estate,
                                 rootRelInfo->ri_RelationDesc);
            }
            tgtslot = mtstate->mt_root_tuple_slot;
            tgtdesc = RelationGetDescr(rootRelInfo->ri_RelationDesc);
          }
          else
          {
            /*
             * If the MERGE targets an inherited table, we insert
             * into the root table, so we must initialize its
             * "new" tuple slot, if not already done, and use its
             * relation descriptor for the projection.
             *
             * For non-inherited tables, rootRelInfo and
             * resultRelInfo are the same, and the "new" tuple
             * slot will already have been initialized.
             */
            if (rootRelInfo->ri_newTupleSlot == NULL)
              rootRelInfo->ri_newTupleSlot =
                table_slot_create(rootRelInfo->ri_RelationDesc,
                          &estate->es_tupleTable);

            tgtslot = rootRelInfo->ri_newTupleSlot;
            tgtdesc = RelationGetDescr(rootRelInfo->ri_RelationDesc);
          }

          action_state->mas_proj =
            ExecBuildProjectionInfo(action->targetList, econtext,
                        tgtslot,
                        &mtstate->ps,
                        tgtdesc);

          mtstate->mt_merge_subcommands |= MERGE_INSERT;
          break;
        case CMD_UPDATE:
          action_state->mas_proj =
            ExecBuildUpdateProjection(action->targetList,
                          true,
                          action->updateColnos,
                          relationDesc,
                          econtext,
                          resultRelInfo->ri_newTupleSlot,
                          &mtstate->ps);
          mtstate->mt_merge_subcommands |= MERGE_UPDATE;
          break;
        case CMD_DELETE:
          mtstate->mt_merge_subcommands |= MERGE_DELETE;
          break;
        case CMD_NOTHING:
          break;
        default:
          elog(ERROR, "unknown action in MERGE WHEN clause");
          break;
      }
    }
  }

  /*
   * If the MERGE targets an inherited table, any INSERT actions will use
   * rootRelInfo, and rootRelInfo will not be in the resultRelInfo array.
   * Therefore we must initialize its WITH CHECK OPTION constraints and
   * RETURNING projection, as ExecInitModifyTable did for the resultRelInfo
   * entries.
   *
   * Note that the planner does not build a withCheckOptionList or
   * returningList for the root relation, but as in ExecInitPartitionInfo,
   * we can use the first resultRelInfo entry as a reference to calculate
   * the attno's for the root table.
   */
  if (rootRelInfo != mtstate->resultRelInfo &&
    rootRelInfo->ri_RelationDesc->rd_rel->relkind != RELKIND_PARTITIONED_TABLE &&
    (mtstate->mt_merge_subcommands & MERGE_INSERT) != 0)
  {
    ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
    Relation  rootRelation = rootRelInfo->ri_RelationDesc;
    Relation  firstResultRel = mtstate->resultRelInfo[0].ri_RelationDesc;
    int     firstVarno = mtstate->resultRelInfo[0].ri_RangeTableIndex;
    AttrMap    *part_attmap = NULL;
    bool    found_whole_row;

    if (node->withCheckOptionLists != NIL)
    {
      List     *wcoList;
      List     *wcoExprs = NIL;

      /* There should be as many WCO lists as result rels */
      Assert(list_length(node->withCheckOptionLists) ==
           list_length(node->resultRelations));

      /*
       * Use the first WCO list as a reference. In the most common case,
       * this will be for the same relation as rootRelInfo, and so there
       * will be no need to adjust its attno's.
       */
      wcoList = linitial(node->withCheckOptionLists);
      if (rootRelation != firstResultRel)
      {
        /* Convert any Vars in it to contain the root's attno's */
        part_attmap =
          build_attrmap_by_name(RelationGetDescr(rootRelation),
                      RelationGetDescr(firstResultRel),
                      false);

        wcoList = (List *)
          map_variable_attnos((Node *) wcoList,
                    firstVarno, 0,
                    part_attmap,
                    RelationGetForm(rootRelation)->reltype,
                    &found_whole_row);
      }

      foreach(lc, wcoList)
      {
        WithCheckOption *wco = lfirst_node(WithCheckOption, lc);
        ExprState  *wcoExpr = ExecInitQual(castNode(List, wco->qual),
                           &mtstate->ps);

        wcoExprs = lappend(wcoExprs, wcoExpr);
      }

      rootRelInfo->ri_WithCheckOptions = wcoList;
      rootRelInfo->ri_WithCheckOptionExprs = wcoExprs;
    }

    if (node->returningLists != NIL)
    {
      List     *returningList;

      /* There should be as many returning lists as result rels */
      Assert(list_length(node->returningLists) ==
           list_length(node->resultRelations));

      /*
       * Use the first returning list as a reference. In the most common
       * case, this will be for the same relation as rootRelInfo, and so
       * there will be no need to adjust its attno's.
       */
      returningList = linitial(node->returningLists);
      if (rootRelation != firstResultRel)
      {
        /* Convert any Vars in it to contain the root's attno's */
        if (part_attmap == NULL)
          part_attmap =
            build_attrmap_by_name(RelationGetDescr(rootRelation),
                        RelationGetDescr(firstResultRel),
                        false);

        returningList = (List *)
          map_variable_attnos((Node *) returningList,
                    firstVarno, 0,
                    part_attmap,
                    RelationGetForm(rootRelation)->reltype,
                    &found_whole_row);
      }
      rootRelInfo->ri_returningList = returningList;

      /* Initialize the RETURNING projection */
      rootRelInfo->ri_projectReturning =
        ExecBuildProjectionInfo(returningList, econtext,
                    mtstate->ps.ps_ResultTupleSlot,
                    &mtstate->ps,
                    RelationGetDescr(rootRelation));
    }
  }
}

/*
 * Initializes the tuple slots in a ResultRelInfo for any MERGE action.
 *
 * We mark 'projectNewInfoValid' even though the projections themselves
 * are not initialized here.
 */
void
ExecInitMergeTupleSlots(ModifyTableState *mtstate,
            ResultRelInfo *resultRelInfo)
{
  EState     *estate = mtstate->ps.state;

  Assert(!resultRelInfo->ri_projectNewInfoValid);

  resultRelInfo->ri_oldTupleSlot =
    table_slot_create(resultRelInfo->ri_RelationDesc,
              &estate->es_tupleTable);
  resultRelInfo->ri_newTupleSlot =
    table_slot_create(resultRelInfo->ri_RelationDesc,
              &estate->es_tupleTable);
  resultRelInfo->ri_projectNewInfoValid = true;
}

/*
 * Process BEFORE EACH STATEMENT triggers
 */
static void
fireBSTriggers(ModifyTableState *node)
{
  ModifyTable *plan = (ModifyTable *) node->ps.plan;
  ResultRelInfo *resultRelInfo = node->rootResultRelInfo;

  switch (node->operation)
  {
    case CMD_INSERT:
      ExecBSInsertTriggers(node->ps.state, resultRelInfo);
      if (plan->onConflictAction == ONCONFLICT_UPDATE)
        ExecBSUpdateTriggers(node->ps.state,
                   resultRelInfo);
      break;
    case CMD_UPDATE:
      ExecBSUpdateTriggers(node->ps.state, resultRelInfo);
      break;
    case CMD_DELETE:
      ExecBSDeleteTriggers(node->ps.state, resultRelInfo);
      break;
    case CMD_MERGE:
      if (node->mt_merge_subcommands & MERGE_INSERT)
        ExecBSInsertTriggers(node->ps.state, resultRelInfo);
      if (node->mt_merge_subcommands & MERGE_UPDATE)
        ExecBSUpdateTriggers(node->ps.state, resultRelInfo);
      if (node->mt_merge_subcommands & MERGE_DELETE)
        ExecBSDeleteTriggers(node->ps.state, resultRelInfo);
      break;
    default:
      elog(ERROR, "unknown operation");
      break;
  }
}

/*
 * Process AFTER EACH STATEMENT triggers
 */
static void
fireASTriggers(ModifyTableState *node)
{
  ModifyTable *plan = (ModifyTable *) node->ps.plan;
  ResultRelInfo *resultRelInfo = node->rootResultRelInfo;

  switch (node->operation)
  {
    case CMD_INSERT:
      if (plan->onConflictAction == ONCONFLICT_UPDATE)
        ExecASUpdateTriggers(node->ps.state,
                   resultRelInfo,
                   node->mt_oc_transition_capture);
      ExecASInsertTriggers(node->ps.state, resultRelInfo,
                 node->mt_transition_capture);
      break;
    case CMD_UPDATE:
      ExecASUpdateTriggers(node->ps.state, resultRelInfo,
                 node->mt_transition_capture);
      break;
    case CMD_DELETE:
      ExecASDeleteTriggers(node->ps.state, resultRelInfo,
                 node->mt_transition_capture);
      break;
    case CMD_MERGE:
      if (node->mt_merge_subcommands & MERGE_DELETE)
        ExecASDeleteTriggers(node->ps.state, resultRelInfo,
                   node->mt_transition_capture);
      if (node->mt_merge_subcommands & MERGE_UPDATE)
        ExecASUpdateTriggers(node->ps.state, resultRelInfo,
                   node->mt_transition_capture);
      if (node->mt_merge_subcommands & MERGE_INSERT)
        ExecASInsertTriggers(node->ps.state, resultRelInfo,
                   node->mt_transition_capture);
      break;
    default:
      elog(ERROR, "unknown operation");
      break;
  }
}

/*
 * Set up the state needed for collecting transition tuples for AFTER
 * triggers.
 */
static void
ExecSetupTransitionCaptureState(ModifyTableState *mtstate, EState *estate)
{
  ModifyTable *plan = (ModifyTable *) mtstate->ps.plan;
  ResultRelInfo *targetRelInfo = mtstate->rootResultRelInfo;

  /* Check for transition tables on the directly targeted relation. */
  mtstate->mt_transition_capture =
    MakeTransitionCaptureState(targetRelInfo->ri_TrigDesc,
                   RelationGetRelid(targetRelInfo->ri_RelationDesc),
                   mtstate->operation);
  if (plan->operation == CMD_INSERT &&
    plan->onConflictAction == ONCONFLICT_UPDATE)
    mtstate->mt_oc_transition_capture =
      MakeTransitionCaptureState(targetRelInfo->ri_TrigDesc,
                     RelationGetRelid(targetRelInfo->ri_RelationDesc),
                     CMD_UPDATE);
}

/*
 * ExecPrepareTupleRouting --- prepare for routing one tuple
 *
 * Determine the partition in which the tuple in slot is to be inserted,
 * and return its ResultRelInfo in *partRelInfo.  The return value is
 * a slot holding the tuple of the partition rowtype.
 *
 * This also sets the transition table information in mtstate based on the
 * selected partition.
 */
static TupleTableSlot *
ExecPrepareTupleRouting(ModifyTableState *mtstate,
            EState *estate,
            PartitionTupleRouting *proute,
            ResultRelInfo *targetRelInfo,
            TupleTableSlot *slot,
            ResultRelInfo **partRelInfo)
{
  ResultRelInfo *partrel;
  TupleConversionMap *map;

  /*
   * Lookup the target partition's ResultRelInfo.  If ExecFindPartition does
   * not find a valid partition for the tuple in 'slot' then an error is
   * raised.  An error may also be raised if the found partition is not a
   * valid target for INSERTs.  This is required since a partitioned table
   * UPDATE to another partition becomes a DELETE+INSERT.
   */
  partrel = ExecFindPartition(mtstate, targetRelInfo, proute, slot, estate);

  /*
   * If we're capturing transition tuples, we might need to convert from the
   * partition rowtype to root partitioned table's rowtype.  But if there
   * are no BEFORE triggers on the partition that could change the tuple, we
   * can just remember the original unconverted tuple to avoid a needless
   * round trip conversion.
   */
  if (mtstate->mt_transition_capture != NULL)
  {
    bool    has_before_insert_row_trig;

    has_before_insert_row_trig = (partrel->ri_TrigDesc &&
                    partrel->ri_TrigDesc->trig_insert_before_row);

    mtstate->mt_transition_capture->tcs_original_insert_tuple =
      !has_before_insert_row_trig ? slot : NULL;
  }

  /*
   * Convert the tuple, if necessary.
   */
  map = ExecGetRootToChildMap(partrel, estate);
  if (map != NULL)
  {
    TupleTableSlot *new_slot = partrel->ri_PartitionTupleSlot;

    slot = execute_attr_map_slot(map->attrMap, slot, new_slot);
  }

  *partRelInfo = partrel;
  return slot;
}

/* ----------------------------------------------------------------
 *     ExecModifyTable
 *
 *    Perform table modifications as required, and return RETURNING results
 *    if needed.
 * ----------------------------------------------------------------
 */
static TupleTableSlot *
ExecModifyTable(PlanState *pstate)
{
  ModifyTableState *node = castNode(ModifyTableState, pstate);
  ModifyTableContext context;
  EState     *estate = node->ps.state;
  CmdType   operation = node->operation;
  ResultRelInfo *resultRelInfo;
  PlanState  *subplanstate;
  TupleTableSlot *slot;
  TupleTableSlot *oldSlot;
  ItemPointerData tuple_ctid;
  HeapTupleData oldtupdata;
  HeapTuple oldtuple;
  ItemPointer tupleid;
  bool    tuplock;

  CHECK_FOR_INTERRUPTS();

  /*
   * This should NOT get called during EvalPlanQual; we should have passed a
   * subplan tree to EvalPlanQual, instead.  Use a runtime test not just
   * Assert because this condition is easy to miss in testing.  (Note:
   * although ModifyTable should not get executed within an EvalPlanQual
   * operation, we do have to allow it to be initialized and shut down in
   * case it is within a CTE subplan.  Hence this test must be here, not in
   * ExecInitModifyTable.)
   */
  if (estate->es_epq_active != NULL)
    elog(ERROR, "ModifyTable should not be called during EvalPlanQual");

  /*
   * If we've already completed processing, don't try to do more.  We need
   * this test because ExecPostprocessPlan might call us an extra time, and
   * our subplan's nodes aren't necessarily robust against being called
   * extra times.
   */
  if (node->mt_done)
    return NULL;

  /*
   * On first call, fire BEFORE STATEMENT triggers before proceeding.
   */
  if (node->fireBSTriggers)
  {
    fireBSTriggers(node);
    node->fireBSTriggers = false;
  }

  /* Preload local variables */
  resultRelInfo = node->resultRelInfo + node->mt_lastResultIndex;
  subplanstate = outerPlanState(node);

  /* Set global context */
  context.mtstate = node;
  context.epqstate = &node->mt_epqstate;
  context.estate = estate;

  /*
   * Fetch rows from subplan, and execute the required table modification
   * for each row.
   */
  for (;;)
  {
    /*
     * Reset the per-output-tuple exprcontext.  This is needed because
     * triggers expect to use that context as workspace.  It's a bit ugly
     * to do this below the top level of the plan, however.  We might need
     * to rethink this later.
     */
    ResetPerTupleExprContext(estate);

    /*
     * Reset per-tuple memory context used for processing on conflict and
     * returning clauses, to free any expression evaluation storage
     * allocated in the previous cycle.
     */
    if (pstate->ps_ExprContext)
      ResetExprContext(pstate->ps_ExprContext);

    /*
     * If there is a pending MERGE ... WHEN NOT MATCHED [BY TARGET] action
     * to execute, do so now --- see the comments in ExecMerge().
     */
    if (node->mt_merge_pending_not_matched != NULL)
    {
      context.planSlot = node->mt_merge_pending_not_matched;
      context.cpDeletedSlot = NULL;

      slot = ExecMergeNotMatched(&context, node->resultRelInfo,
                     node->canSetTag);

      /* Clear the pending action */
      node->mt_merge_pending_not_matched = NULL;

      /*
       * If we got a RETURNING result, return it to the caller.  We'll
       * continue the work on next call.
       */
      if (slot)
        return slot;

      continue;     /* continue with the next tuple */
    }

    /* Fetch the next row from subplan */
    context.planSlot = ExecProcNode(subplanstate);
    context.cpDeletedSlot = NULL;

    /* No more tuples to process? */
    if (TupIsNull(context.planSlot))
      break;

    /*
     * When there are multiple result relations, each tuple contains a
     * junk column that gives the OID of the rel from which it came.
     * Extract it and select the correct result relation.
     */
    if (AttributeNumberIsValid(node->mt_resultOidAttno))
    {
      Datum   datum;
      bool    isNull;
      Oid     resultoid;

      datum = ExecGetJunkAttribute(context.planSlot, node->mt_resultOidAttno,
                     &isNull);
      if (isNull)
      {
        /*
         * For commands other than MERGE, any tuples having InvalidOid
         * for tableoid are errors.  For MERGE, we may need to handle
         * them as WHEN NOT MATCHED clauses if any, so do that.
         *
         * Note that we use the node's toplevel resultRelInfo, not any
         * specific partition's.
         */
        if (operation == CMD_MERGE)
        {
          EvalPlanQualSetSlot(&node->mt_epqstate, context.planSlot);

          slot = ExecMerge(&context, node->resultRelInfo,
                   NULL, NULL, node->canSetTag);

          /*
           * If we got a RETURNING result, return it to the caller.
           * We'll continue the work on next call.
           */
          if (slot)
            return slot;

          continue; /* continue with the next tuple */
        }

        elog(ERROR, "tableoid is NULL");
      }
      resultoid = DatumGetObjectId(datum);

      /* If it's not the same as last time, we need to locate the rel */
      if (resultoid != node->mt_lastResultOid)
        resultRelInfo = ExecLookupResultRelByOid(node, resultoid,
                             false, true);
    }

    /*
     * If resultRelInfo->ri_usesFdwDirectModify is true, all we need to do
     * here is compute the RETURNING expressions.
     */
    if (resultRelInfo->ri_usesFdwDirectModify)
    {
      Assert(resultRelInfo->ri_projectReturning);

      /*
       * A scan slot containing the data that was actually inserted,
       * updated or deleted has already been made available to
       * ExecProcessReturning by IterateDirectModify, so no need to
       * provide it here.  The individual old and new slots are not
       * needed, since direct-modify is disabled if the RETURNING list
       * refers to OLD/NEW values.
       */
      Assert((resultRelInfo->ri_projectReturning->pi_state.flags & EEO_FLAG_HAS_OLD) == 0 &&
           (resultRelInfo->ri_projectReturning->pi_state.flags & EEO_FLAG_HAS_NEW) == 0);

      slot = ExecProcessReturning(&context, resultRelInfo, operation,
                    NULL, NULL, context.planSlot);

      return slot;
    }

    EvalPlanQualSetSlot(&node->mt_epqstate, context.planSlot);
    slot = context.planSlot;

    tupleid = NULL;
    oldtuple = NULL;

    /*
     * For UPDATE/DELETE/MERGE, fetch the row identity info for the tuple
     * to be updated/deleted/merged.  For a heap relation, that's a TID;
     * otherwise we may have a wholerow junk attr that carries the old
     * tuple in toto.  Keep this in step with the part of
     * ExecInitModifyTable that sets up ri_RowIdAttNo.
     */
    if (operation == CMD_UPDATE || operation == CMD_DELETE ||
      operation == CMD_MERGE)
    {
      char    relkind;
      Datum   datum;
      bool    isNull;

      relkind = resultRelInfo->ri_RelationDesc->rd_rel->relkind;
      if (relkind == RELKIND_RELATION ||
        relkind == RELKIND_MATVIEW ||
        relkind == RELKIND_PARTITIONED_TABLE)
      {
        /* ri_RowIdAttNo refers to a ctid attribute */
        Assert(AttributeNumberIsValid(resultRelInfo->ri_RowIdAttNo));
        datum = ExecGetJunkAttribute(slot,
                       resultRelInfo->ri_RowIdAttNo,
                       &isNull);

        /*
         * For commands other than MERGE, any tuples having a null row
         * identifier are errors.  For MERGE, we may need to handle
         * them as WHEN NOT MATCHED clauses if any, so do that.
         *
         * Note that we use the node's toplevel resultRelInfo, not any
         * specific partition's.
         */
        if (isNull)
        {
          if (operation == CMD_MERGE)
          {
            EvalPlanQualSetSlot(&node->mt_epqstate, context.planSlot);

            slot = ExecMerge(&context, node->resultRelInfo,
                     NULL, NULL, node->canSetTag);

            /*
             * If we got a RETURNING result, return it to the
             * caller.  We'll continue the work on next call.
             */
            if (slot)
              return slot;

            continue; /* continue with the next tuple */
          }

          elog(ERROR, "ctid is NULL");
        }

        tupleid = (ItemPointer) DatumGetPointer(datum);
        tuple_ctid = *tupleid;  /* be sure we don't free ctid!! */
        tupleid = &tuple_ctid;
      }

      /*
       * Use the wholerow attribute, when available, to reconstruct the
       * old relation tuple.  The old tuple serves one or both of two
       * purposes: 1) it serves as the OLD tuple for row triggers, 2) it
       * provides values for any unchanged columns for the NEW tuple of
       * an UPDATE, because the subplan does not produce all the columns
       * of the target table.
       *
       * Note that the wholerow attribute does not carry system columns,
       * so foreign table triggers miss seeing those, except that we
       * know enough here to set t_tableOid.  Quite separately from
       * this, the FDW may fetch its own junk attrs to identify the row.
       *
       * Other relevant relkinds, currently limited to views, always
       * have a wholerow attribute.
       */
      else if (AttributeNumberIsValid(resultRelInfo->ri_RowIdAttNo))
      {
        datum = ExecGetJunkAttribute(slot,
                       resultRelInfo->ri_RowIdAttNo,
                       &isNull);

        /*
         * For commands other than MERGE, any tuples having a null row
         * identifier are errors.  For MERGE, we may need to handle
         * them as WHEN NOT MATCHED clauses if any, so do that.
         *
         * Note that we use the node's toplevel resultRelInfo, not any
         * specific partition's.
         */
        if (isNull)
        {
          if (operation == CMD_MERGE)
          {
            EvalPlanQualSetSlot(&node->mt_epqstate, context.planSlot);

            slot = ExecMerge(&context, node->resultRelInfo,
                     NULL, NULL, node->canSetTag);

            /*
             * If we got a RETURNING result, return it to the
             * caller.  We'll continue the work on next call.
             */
            if (slot)
              return slot;

            continue; /* continue with the next tuple */
          }

          elog(ERROR, "wholerow is NULL");
        }

        oldtupdata.t_data = DatumGetHeapTupleHeader(datum);
        oldtupdata.t_len =
          HeapTupleHeaderGetDatumLength(oldtupdata.t_data);
        ItemPointerSetInvalid(&(oldtupdata.t_self));
        /* Historically, view triggers see invalid t_tableOid. */
        oldtupdata.t_tableOid =
          (relkind == RELKIND_VIEW) ? InvalidOid :
          RelationGetRelid(resultRelInfo->ri_RelationDesc);

        oldtuple = &oldtupdata;
      }
      else
      {
        /* Only foreign tables are allowed to omit a row-ID attr */
        Assert(relkind == RELKIND_FOREIGN_TABLE);
      }
    }

    switch (operation)
    {
      case CMD_INSERT:
        /* Initialize projection info if first time for this table */
        if (unlikely(!resultRelInfo->ri_projectNewInfoValid))
          ExecInitInsertProjection(node, resultRelInfo);
        slot = ExecGetInsertNewTuple(resultRelInfo, context.planSlot);
        slot = ExecInsert(&context, resultRelInfo, slot,
                  node->canSetTag, NULL, NULL);
        break;

      case CMD_UPDATE:
        tuplock = false;

        /* Initialize projection info if first time for this table */
        if (unlikely(!resultRelInfo->ri_projectNewInfoValid))
          ExecInitUpdateProjection(node, resultRelInfo);

        /*
         * Make the new tuple by combining plan's output tuple with
         * the old tuple being updated.
         */
        oldSlot = resultRelInfo->ri_oldTupleSlot;
        if (oldtuple != NULL)
        {
          Assert(!resultRelInfo->ri_needLockTagTuple);
          /* Use the wholerow junk attr as the old tuple. */
          ExecForceStoreHeapTuple(oldtuple, oldSlot, false);
        }
        else
        {
          /* Fetch the most recent version of old tuple. */
          Relation  relation = resultRelInfo->ri_RelationDesc;

          if (resultRelInfo->ri_needLockTagTuple)
          {
            LockTuple(relation, tupleid, InplaceUpdateTupleLock);
            tuplock = true;
          }
          if (!table_tuple_fetch_row_version(relation, tupleid,
                             SnapshotAny,
                             oldSlot))
            elog(ERROR, "failed to fetch tuple being updated");
        }
        slot = ExecGetUpdateNewTuple(resultRelInfo, context.planSlot,
                       oldSlot);

        /* Now apply the update. */
        slot = ExecUpdate(&context, resultRelInfo, tupleid, oldtuple,
                  oldSlot, slot, node->canSetTag);
        if (tuplock)
          UnlockTuple(resultRelInfo->ri_RelationDesc, tupleid,
                InplaceUpdateTupleLock);
        break;

      case CMD_DELETE:
        slot = ExecDelete(&context, resultRelInfo, tupleid, oldtuple,
                  true, false, node->canSetTag, NULL, NULL, NULL);
        break;

      case CMD_MERGE:
        slot = ExecMerge(&context, resultRelInfo, tupleid, oldtuple,
                 node->canSetTag);
        break;

      default:
        elog(ERROR, "unknown operation");
        break;
    }

    /*
     * If we got a RETURNING result, return it to caller.  We'll continue
     * the work on next call.
     */
    if (slot)
      return slot;
  }

  /*
   * Insert remaining tuples for batch insert.
   */
  if (estate->es_insert_pending_result_relations != NIL)
    ExecPendingInserts(estate);

  /*
   * We're done, but fire AFTER STATEMENT triggers before exiting.
   */
  fireASTriggers(node);

  node->mt_done = true;

  return NULL;
}

/*
 * ExecLookupResultRelByOid
 *    If the table with given OID is among the result relations to be
 *    updated by the given ModifyTable node, return its ResultRelInfo.
 *
 * If not found, return NULL if missing_ok, else raise error.
 *
 * If update_cache is true, then upon successful lookup, update the node's
 * one-element cache.  ONLY ExecModifyTable may pass true for this.
 */
ResultRelInfo *
ExecLookupResultRelByOid(ModifyTableState *node, Oid resultoid,
             bool missing_ok, bool update_cache)
{
  if (node->mt_resultOidHash)
  {
    /* Use the pre-built hash table to locate the rel */
    MTTargetRelLookup *mtlookup;

    mtlookup = (MTTargetRelLookup *)
      hash_search(node->mt_resultOidHash, &resultoid, HASH_FIND, NULL);
    if (mtlookup)
    {
      if (update_cache)
      {
        node->mt_lastResultOid = resultoid;
        node->mt_lastResultIndex = mtlookup->relationIndex;
      }
      return node->resultRelInfo + mtlookup->relationIndex;
    }
  }
  else
  {
    /* With few target rels, just search the ResultRelInfo array */
    for (int ndx = 0; ndx < node->mt_nrels; ndx++)
    {
      ResultRelInfo *rInfo = node->resultRelInfo + ndx;

      if (RelationGetRelid(rInfo->ri_RelationDesc) == resultoid)
      {
        if (update_cache)
        {
          node->mt_lastResultOid = resultoid;
          node->mt_lastResultIndex = ndx;
        }
        return rInfo;
      }
    }
  }

  if (!missing_ok)
    elog(ERROR, "incorrect result relation OID %u", resultoid);
  return NULL;
}

/* ----------------------------------------------------------------
 *    ExecInitModifyTable
 * ----------------------------------------------------------------
 */
ModifyTableState *
ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
{
  ModifyTableState *mtstate;
  Plan     *subplan = outerPlan(node);
  CmdType   operation = node->operation;
  int     total_nrels = list_length(node->resultRelations);
  int     nrels;
  List     *resultRelations = NIL;
  List     *withCheckOptionLists = NIL;
  List     *returningLists = NIL;
  List     *updateColnosLists = NIL;
  List     *mergeActionLists = NIL;
  List     *mergeJoinConditions = NIL;
  ResultRelInfo *resultRelInfo;
  List     *arowmarks;
  ListCell   *l;
  int     i;
  Relation  rel;

  /* check for unsupported flags */
  Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));

  /*
   * Only consider unpruned relations for initializing their ResultRelInfo
   * struct and other fields such as withCheckOptions, etc.
   *
   * Note: We must avoid pruning every result relation.  This is important
   * for MERGE, since even if every result relation is pruned from the
   * subplan, there might still be NOT MATCHED rows, for which there may be
   * INSERT actions to perform.  To allow these actions to be found, at
   * least one result relation must be kept.  Also, when inserting into a
   * partitioned table, ExecInitPartitionInfo() needs a ResultRelInfo struct
   * as a reference for building the ResultRelInfo of the target partition.
   * In either case, it doesn't matter which result relation is kept, so we
   * just keep the first one, if all others have been pruned.  See also,
   * ExecDoInitialPruning(), which ensures that this first result relation
   * has been locked.
   */
  i = 0;
  foreach(l, node->resultRelations)
  {
    Index   rti = lfirst_int(l);
    bool    keep_rel;

    keep_rel = bms_is_member(rti, estate->es_unpruned_relids);
    if (!keep_rel && i == total_nrels - 1 && resultRelations == NIL)
    {
      /* all result relations pruned; keep the first one */
      keep_rel = true;
      rti = linitial_int(node->resultRelations);
      i = 0;
    }

    if (keep_rel)
    {
      resultRelations = lappend_int(resultRelations, rti);
      if (node->withCheckOptionLists)
      {
        List     *withCheckOptions = list_nth_node(List,
                               node->withCheckOptionLists,
                               i);

        withCheckOptionLists = lappend(withCheckOptionLists, withCheckOptions);
      }
      if (node->returningLists)
      {
        List     *returningList = list_nth_node(List,
                              node->returningLists,
                              i);

        returningLists = lappend(returningLists, returningList);
      }
      if (node->updateColnosLists)
      {
        List     *updateColnosList = list_nth(node->updateColnosLists, i);

        updateColnosLists = lappend(updateColnosLists, updateColnosList);
      }
      if (node->mergeActionLists)
      {
        List     *mergeActionList = list_nth(node->mergeActionLists, i);

        mergeActionLists = lappend(mergeActionLists, mergeActionList);
      }
      if (node->mergeJoinConditions)
      {
        List     *mergeJoinCondition = list_nth(node->mergeJoinConditions, i);

        mergeJoinConditions = lappend(mergeJoinConditions, mergeJoinCondition);
      }
    }
    i++;
  }
  nrels = list_length(resultRelations);
  Assert(nrels > 0);

  /*
   * create state structure
   */
  mtstate = makeNode(ModifyTableState);
  mtstate->ps.plan = (Plan *) node;
  mtstate->ps.state = estate;
  mtstate->ps.ExecProcNode = ExecModifyTable;

  mtstate->operation = operation;
  mtstate->canSetTag = node->canSetTag;
  mtstate->mt_done = false;

  mtstate->mt_nrels = nrels;
  mtstate->resultRelInfo = (ResultRelInfo *)
    palloc(nrels * sizeof(ResultRelInfo));

  mtstate->mt_merge_pending_not_matched = NULL;
  mtstate->mt_merge_inserted = 0;
  mtstate->mt_merge_updated = 0;
  mtstate->mt_merge_deleted = 0;
  mtstate->mt_updateColnosLists = updateColnosLists;
  mtstate->mt_mergeActionLists = mergeActionLists;
  mtstate->mt_mergeJoinConditions = mergeJoinConditions;

  /*----------
   * Resolve the target relation. This is the same as:
   *
   * - the relation for which we will fire FOR STATEMENT triggers,
   * - the relation into whose tuple format all captured transition tuples
   *   must be converted, and
   * - the root partitioned table used for tuple routing.
   *
   * If it's a partitioned or inherited table, the root partition or
   * appendrel RTE doesn't appear elsewhere in the plan and its RT index is
   * given explicitly in node->rootRelation.  Otherwise, the target relation
   * is the sole relation in the node->resultRelations list and, since it can
   * never be pruned, also in the resultRelations list constructed above.
   *----------
   */
  if (node->rootRelation > 0)
  {
    Assert(bms_is_member(node->rootRelation, estate->es_unpruned_relids));
    mtstate->rootResultRelInfo = makeNode(ResultRelInfo);
    ExecInitResultRelation(estate, mtstate->rootResultRelInfo,
                 node->rootRelation);
  }
  else
  {
    Assert(list_length(node->resultRelations) == 1);
    Assert(list_length(resultRelations) == 1);
    mtstate->rootResultRelInfo = mtstate->resultRelInfo;
    ExecInitResultRelation(estate, mtstate->resultRelInfo,
                 linitial_int(resultRelations));
  }

  /* set up epqstate with dummy subplan data for the moment */
  EvalPlanQualInit(&mtstate->mt_epqstate, estate, NULL, NIL,
           node->epqParam, resultRelations);
  mtstate->fireBSTriggers = true;

  /*
   * Build state for collecting transition tuples.  This requires having a
   * valid trigger query context, so skip it in explain-only mode.
   */
  if (!(eflags & EXEC_FLAG_EXPLAIN_ONLY))
    ExecSetupTransitionCaptureState(mtstate, estate);

  /*
   * Open all the result relations and initialize the ResultRelInfo structs.
   * (But root relation was initialized above, if it's part of the array.)
   * We must do this before initializing the subplan, because direct-modify
   * FDWs expect their ResultRelInfos to be available.
   */
  resultRelInfo = mtstate->resultRelInfo;
  i = 0;
  foreach(l, resultRelations)
  {
    Index   resultRelation = lfirst_int(l);
    List     *mergeActions = NIL;

    if (mergeActionLists)
      mergeActions = list_nth(mergeActionLists, i);

    if (resultRelInfo != mtstate->rootResultRelInfo)
    {
      ExecInitResultRelation(estate, resultRelInfo, resultRelation);

      /*
       * For child result relations, store the root result relation
       * pointer.  We do so for the convenience of places that want to
       * look at the query's original target relation but don't have the
       * mtstate handy.
       */
      resultRelInfo->ri_RootResultRelInfo = mtstate->rootResultRelInfo;
    }

    /* Initialize the usesFdwDirectModify flag */
    resultRelInfo->ri_usesFdwDirectModify =
      bms_is_member(i, node->fdwDirectModifyPlans);

    /*
     * Verify result relation is a valid target for the current operation
     */
    CheckValidResultRel(resultRelInfo, operation, mergeActions);

    resultRelInfo++;
    i++;
  }

  /*
   * Now we may initialize the subplan.
   */
  outerPlanState(mtstate) = ExecInitNode(subplan, estate, eflags);

  /*
   * Do additional per-result-relation initialization.
   */
  for (i = 0; i < nrels; i++)
  {
    resultRelInfo = &mtstate->resultRelInfo[i];

    /* Let FDWs init themselves for foreign-table result rels */
    if (!resultRelInfo->ri_usesFdwDirectModify &&
      resultRelInfo->ri_FdwRoutine != NULL &&
      resultRelInfo->ri_FdwRoutine->BeginForeignModify != NULL)
    {
      List     *fdw_private = (List *) list_nth(node->fdwPrivLists, i);

      resultRelInfo->ri_FdwRoutine->BeginForeignModify(mtstate,
                               resultRelInfo,
                               fdw_private,
                               i,
                               eflags);
    }

    /*
     * For UPDATE/DELETE/MERGE, find the appropriate junk attr now, either
     * a 'ctid' or 'wholerow' attribute depending on relkind.  For foreign
     * tables, the FDW might have created additional junk attr(s), but
     * those are no concern of ours.
     */
    if (operation == CMD_UPDATE || operation == CMD_DELETE ||
      operation == CMD_MERGE)
    {
      char    relkind;

      relkind = resultRelInfo->ri_RelationDesc->rd_rel->relkind;
      if (relkind == RELKIND_RELATION ||
        relkind == RELKIND_MATVIEW ||
        relkind == RELKIND_PARTITIONED_TABLE)
      {
        resultRelInfo->ri_RowIdAttNo =
          ExecFindJunkAttributeInTlist(subplan->targetlist, "ctid");
        if (!AttributeNumberIsValid(resultRelInfo->ri_RowIdAttNo))
          elog(ERROR, "could not find junk ctid column");
      }
      else if (relkind == RELKIND_FOREIGN_TABLE)
      {
        /*
         * We don't support MERGE with foreign tables for now.  (It's
         * problematic because the implementation uses CTID.)
         */
        Assert(operation != CMD_MERGE);

        /*
         * When there is a row-level trigger, there should be a
         * wholerow attribute.  We also require it to be present in
         * UPDATE and MERGE, so we can get the values of unchanged
         * columns.
         */
        resultRelInfo->ri_RowIdAttNo =
          ExecFindJunkAttributeInTlist(subplan->targetlist,
                         "wholerow");
        if ((mtstate->operation == CMD_UPDATE || mtstate->operation == CMD_MERGE) &&
          !AttributeNumberIsValid(resultRelInfo->ri_RowIdAttNo))
          elog(ERROR, "could not find junk wholerow column");
      }
      else
      {
        /* Other valid target relkinds must provide wholerow */
        resultRelInfo->ri_RowIdAttNo =
          ExecFindJunkAttributeInTlist(subplan->targetlist,
                         "wholerow");
        if (!AttributeNumberIsValid(resultRelInfo->ri_RowIdAttNo))
          elog(ERROR, "could not find junk wholerow column");
      }
    }
  }

  /*
   * If this is an inherited update/delete/merge, there will be a junk
   * attribute named "tableoid" present in the subplan's targetlist.  It
   * will be used to identify the result relation for a given tuple to be
   * updated/deleted/merged.
   */
  mtstate->mt_resultOidAttno =
    ExecFindJunkAttributeInTlist(subplan->targetlist, "tableoid");
  Assert(AttributeNumberIsValid(mtstate->mt_resultOidAttno) || total_nrels == 1);
  mtstate->mt_lastResultOid = InvalidOid; /* force lookup at first tuple */
  mtstate->mt_lastResultIndex = 0;  /* must be zero if no such attr */

  /* Get the root target relation */
  rel = mtstate->rootResultRelInfo->ri_RelationDesc;

  /*
   * Build state for tuple routing if it's a partitioned INSERT.  An UPDATE
   * or MERGE might need this too, but only if it actually moves tuples
   * between partitions; in that case setup is done by
   * ExecCrossPartitionUpdate.
   */
  if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
    operation == CMD_INSERT)
    mtstate->mt_partition_tuple_routing =
      ExecSetupPartitionTupleRouting(estate, rel);

  /*
   * Initialize any WITH CHECK OPTION constraints if needed.
   */
  resultRelInfo = mtstate->resultRelInfo;
  foreach(l, withCheckOptionLists)
  {
    List     *wcoList = (List *) lfirst(l);
    List     *wcoExprs = NIL;
    ListCell   *ll;

    foreach(ll, wcoList)
    {
      WithCheckOption *wco = (WithCheckOption *) lfirst(ll);
      ExprState  *wcoExpr = ExecInitQual((List *) wco->qual,
                         &mtstate->ps);

      wcoExprs = lappend(wcoExprs, wcoExpr);
    }

    resultRelInfo->ri_WithCheckOptions = wcoList;
    resultRelInfo->ri_WithCheckOptionExprs = wcoExprs;
    resultRelInfo++;
  }

  /*
   * Initialize RETURNING projections if needed.
   */
  if (returningLists)
  {
    TupleTableSlot *slot;
    ExprContext *econtext;

    /*
     * Initialize result tuple slot and assign its rowtype using the plan
     * node's declared targetlist, which the planner set up to be the same
     * as the first (before runtime pruning) RETURNING list.  We assume
     * all the result rels will produce compatible output.
     */
    ExecInitResultTupleSlotTL(&mtstate->ps, &TTSOpsVirtual);
    slot = mtstate->ps.ps_ResultTupleSlot;

    /* Need an econtext too */
    if (mtstate->ps.ps_ExprContext == NULL)
      ExecAssignExprContext(estate, &mtstate->ps);
    econtext = mtstate->ps.ps_ExprContext;

    /*
     * Build a projection for each result rel.
     */
    resultRelInfo = mtstate->resultRelInfo;
    foreach(l, returningLists)
    {
      List     *rlist = (List *) lfirst(l);

      resultRelInfo->ri_returningList = rlist;
      resultRelInfo->ri_projectReturning =
        ExecBuildProjectionInfo(rlist, econtext, slot, &mtstate->ps,
                    resultRelInfo->ri_RelationDesc->rd_att);
      resultRelInfo++;
    }
  }
  else
  {
    /*
     * We still must construct a dummy result tuple type, because InitPlan
     * expects one (maybe should change that?).
     */
    ExecInitResultTypeTL(&mtstate->ps);

    mtstate->ps.ps_ExprContext = NULL;
  }

  /* Set the list of arbiter indexes if needed for ON CONFLICT */
  resultRelInfo = mtstate->resultRelInfo;
  if (node->onConflictAction != ONCONFLICT_NONE)
  {
    /* insert may only have one relation, inheritance is not expanded */
    Assert(total_nrels == 1);
    resultRelInfo->ri_onConflictArbiterIndexes = node->arbiterIndexes;
  }

  /*
   * If needed, Initialize target list, projection and qual for ON CONFLICT
   * DO UPDATE.
   */
  if (node->onConflictAction == ONCONFLICT_UPDATE)
  {
    OnConflictSetState *onconfl = makeNode(OnConflictSetState);
    ExprContext *econtext;
    TupleDesc relationDesc;

    /* already exists if created by RETURNING processing above */
    if (mtstate->ps.ps_ExprContext == NULL)
      ExecAssignExprContext(estate, &mtstate->ps);

    econtext = mtstate->ps.ps_ExprContext;
    relationDesc = resultRelInfo->ri_RelationDesc->rd_att;

    /* create state for DO UPDATE SET operation */
    resultRelInfo->ri_onConflict = onconfl;

    /* initialize slot for the existing tuple */
    onconfl->oc_Existing =
      table_slot_create(resultRelInfo->ri_RelationDesc,
                &mtstate->ps.state->es_tupleTable);

    /*
     * Create the tuple slot for the UPDATE SET projection. We want a slot
     * of the table's type here, because the slot will be used to insert
     * into the table, and for RETURNING processing - which may access
     * system attributes.
     */
    onconfl->oc_ProjSlot =
      table_slot_create(resultRelInfo->ri_RelationDesc,
                &mtstate->ps.state->es_tupleTable);

    /* build UPDATE SET projection state */
    onconfl->oc_ProjInfo =
      ExecBuildUpdateProjection(node->onConflictSet,
                    true,
                    node->onConflictCols,
                    relationDesc,
                    econtext,
                    onconfl->oc_ProjSlot,
                    &mtstate->ps);

    /* initialize state to evaluate the WHERE clause, if any */
    if (node->onConflictWhere)
    {
      ExprState  *qualexpr;

      qualexpr = ExecInitQual((List *) node->onConflictWhere,
                  &mtstate->ps);
      onconfl->oc_WhereClause = qualexpr;
    }
  }

  /*
   * If we have any secondary relations in an UPDATE or DELETE, they need to
   * be treated like non-locked relations in SELECT FOR UPDATE, i.e., the
   * EvalPlanQual mechanism needs to be told about them.  This also goes for
   * the source relations in a MERGE.  Locate the relevant ExecRowMarks.
   */
  arowmarks = NIL;
  foreach(l, node->rowMarks)
  {
    PlanRowMark *rc = lfirst_node(PlanRowMark, l);
    ExecRowMark *erm;
    ExecAuxRowMark *aerm;

    /*
     * Ignore "parent" rowmarks, because they are irrelevant at runtime.
     * Also ignore the rowmarks belonging to child tables that have been
     * pruned in ExecDoInitialPruning().
     */
    if (rc->isParent ||
      !bms_is_member(rc->rti, estate->es_unpruned_relids))
      continue;

    /* Find ExecRowMark and build ExecAuxRowMark */
    erm = ExecFindRowMark(estate, rc->rti, false);
    aerm = ExecBuildAuxRowMark(erm, subplan->targetlist);
    arowmarks = lappend(arowmarks, aerm);
  }

  /* For a MERGE command, initialize its state */
  if (mtstate->operation == CMD_MERGE)
    ExecInitMerge(mtstate, estate);

  EvalPlanQualSetPlan(&mtstate->mt_epqstate, subplan, arowmarks);

  /*
   * If there are a lot of result relations, use a hash table to speed the
   * lookups.  If there are not a lot, a simple linear search is faster.
   *
   * It's not clear where the threshold is, but try 64 for starters.  In a
   * debugging build, use a small threshold so that we get some test
   * coverage of both code paths.
   */
#ifdef USE_ASSERT_CHECKING
#define MT_NRELS_HASH 4
#else
#define MT_NRELS_HASH 64
#endif
  if (nrels >= MT_NRELS_HASH)
  {
    HASHCTL   hash_ctl;

    hash_ctl.keysize = sizeof(Oid);
    hash_ctl.entrysize = sizeof(MTTargetRelLookup);
    hash_ctl.hcxt = CurrentMemoryContext;
    mtstate->mt_resultOidHash =
      hash_create("ModifyTable target hash",
            nrels, &hash_ctl,
            HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
    for (i = 0; i < nrels; i++)
    {
      Oid     hashkey;
      MTTargetRelLookup *mtlookup;
      bool    found;

      resultRelInfo = &mtstate->resultRelInfo[i];
      hashkey = RelationGetRelid(resultRelInfo->ri_RelationDesc);
      mtlookup = (MTTargetRelLookup *)
        hash_search(mtstate->mt_resultOidHash, &hashkey,
              HASH_ENTER, &found);
      Assert(!found);
      mtlookup->relationIndex = i;
    }
  }
  else
    mtstate->mt_resultOidHash = NULL;

  /*
   * Determine if the FDW supports batch insert and determine the batch size
   * (a FDW may support batching, but it may be disabled for the
   * server/table).
   *
   * We only do this for INSERT, so that for UPDATE/DELETE the batch size
   * remains set to 0.
   */
  if (operation == CMD_INSERT)
  {
    /* insert may only have one relation, inheritance is not expanded */
    Assert(total_nrels == 1);
    resultRelInfo = mtstate->resultRelInfo;
    if (!resultRelInfo->ri_usesFdwDirectModify &&
      resultRelInfo->ri_FdwRoutine != NULL &&
      resultRelInfo->ri_FdwRoutine->GetForeignModifyBatchSize &&
      resultRelInfo->ri_FdwRoutine->ExecForeignBatchInsert)
    {
      resultRelInfo->ri_BatchSize =
        resultRelInfo->ri_FdwRoutine->GetForeignModifyBatchSize(resultRelInfo);
      Assert(resultRelInfo->ri_BatchSize >= 1);
    }
    else
      resultRelInfo->ri_BatchSize = 1;
  }

  /*
   * Lastly, if this is not the primary (canSetTag) ModifyTable node, add it
   * to estate->es_auxmodifytables so that it will be run to completion by
   * ExecPostprocessPlan.  (It'd actually work fine to add the primary
   * ModifyTable node too, but there's no need.)  Note the use of lcons not
   * lappend: we need later-initialized ModifyTable nodes to be shut down
   * before earlier ones.  This ensures that we don't throw away RETURNING
   * rows that need to be seen by a later CTE subplan.
   */
  if (!mtstate->canSetTag)
    estate->es_auxmodifytables = lcons(mtstate,
                       estate->es_auxmodifytables);

  return mtstate;
}

/* ----------------------------------------------------------------
 *    ExecEndModifyTable
 *
 *    Shuts down the plan.
 *
 *    Returns nothing of interest.
 * ----------------------------------------------------------------
 */
void
ExecEndModifyTable(ModifyTableState *node)
{
  int     i;

  /*
   * Allow any FDWs to shut down
   */
  for (i = 0; i < node->mt_nrels; i++)
  {
    int     j;
    ResultRelInfo *resultRelInfo = node->resultRelInfo + i;

    if (!resultRelInfo->ri_usesFdwDirectModify &&
      resultRelInfo->ri_FdwRoutine != NULL &&
      resultRelInfo->ri_FdwRoutine->EndForeignModify != NULL)
      resultRelInfo->ri_FdwRoutine->EndForeignModify(node->ps.state,
                               resultRelInfo);

    /*
     * Cleanup the initialized batch slots. This only matters for FDWs
     * with batching, but the other cases will have ri_NumSlotsInitialized
     * == 0.
     */
    for (j = 0; j < resultRelInfo->ri_NumSlotsInitialized; j++)
    {
      ExecDropSingleTupleTableSlot(resultRelInfo->ri_Slots[j]);
      ExecDropSingleTupleTableSlot(resultRelInfo->ri_PlanSlots[j]);
    }
  }

  /*
   * Close all the partitioned tables, leaf partitions, and their indices
   * and release the slot used for tuple routing, if set.
   */
  if (node->mt_partition_tuple_routing)
  {
    ExecCleanupTupleRouting(node, node->mt_partition_tuple_routing);

    if (node->mt_root_tuple_slot)
      ExecDropSingleTupleTableSlot(node->mt_root_tuple_slot);
  }

  /*
   * Terminate EPQ execution if active
   */
  EvalPlanQualEnd(&node->mt_epqstate);

  /*
   * shut down subplan
   */
  ExecEndNode(outerPlanState(node));
}

void
ExecReScanModifyTable(ModifyTableState *node)
{
  /*
   * Currently, we don't need to support rescan on ModifyTable nodes. The
   * semantics of that would be a bit debatable anyway.
   */
  elog(ERROR, "ExecReScanModifyTable is not implemented");
}

Coverage Report

Created: 2025-07-03 06:49