/src/postgres/src/backend/partitioning/partprune.c

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/*-------------------------------------------------------------------------
 *
 * partprune.c
 *    Support for partition pruning during query planning and execution
 *
 * This module implements partition pruning using the information contained in
 * a table's partition descriptor, query clauses, and run-time parameters.
 *
 * During planning, clauses that can be matched to the table's partition key
 * are turned into a set of "pruning steps", which are then executed to
 * identify a set of partitions (as indexes in the RelOptInfo->part_rels
 * array) that satisfy the constraints in the step.  Partitions not in the set
 * are said to have been pruned.
 *
 * A base pruning step may involve expressions whose values are only known
 * during execution, such as Params, in which case pruning cannot occur
 * entirely during planning.  In that case, such steps are included alongside
 * the plan, so that they can be used by the executor for further pruning.
 *
 * There are two kinds of pruning steps.  A "base" pruning step represents
 * tests on partition key column(s), typically comparisons to expressions.
 * A "combine" pruning step represents a Boolean connector (AND/OR), and
 * combines the outputs of some previous steps using the appropriate
 * combination method.
 *
 * See gen_partprune_steps_internal() for more details on step generation.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *      src/backend/partitioning/partprune.c
 *
 *-------------------------------------------------------------------------
*/
#include "postgres.h"

#include "access/hash.h"
#include "access/nbtree.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_opfamily.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "executor/executor.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/appendinfo.h"
#include "optimizer/cost.h"
#include "optimizer/optimizer.h"
#include "optimizer/pathnode.h"
#include "parser/parsetree.h"
#include "partitioning/partbounds.h"
#include "partitioning/partprune.h"
#include "utils/array.h"
#include "utils/lsyscache.h"


/*
 * Information about a clause matched with a partition key.
 */
typedef struct PartClauseInfo
{
  int     keyno;      /* Partition key number (0 to partnatts - 1) */
  Oid     opno;     /* operator used to compare partkey to expr */
  bool    op_is_ne;   /* is clause's original operator <> ? */
  Expr     *expr;     /* expr the partition key is compared to */
  Oid     cmpfn;      /* Oid of function to compare 'expr' to the
                 * partition key */
  int     op_strategy;  /* btree strategy identifying the operator */
} PartClauseInfo;

/*
 * PartClauseMatchStatus
 *    Describes the result of match_clause_to_partition_key()
 */
typedef enum PartClauseMatchStatus
{
  PARTCLAUSE_NOMATCH,
  PARTCLAUSE_MATCH_CLAUSE,
  PARTCLAUSE_MATCH_NULLNESS,
  PARTCLAUSE_MATCH_STEPS,
  PARTCLAUSE_MATCH_CONTRADICT,
  PARTCLAUSE_UNSUPPORTED,
} PartClauseMatchStatus;

/*
 * PartClauseTarget
 *    Identifies which qual clauses we can use for generating pruning steps
 */
typedef enum PartClauseTarget
{
  PARTTARGET_PLANNER,     /* want to prune during planning */
  PARTTARGET_INITIAL,     /* want to prune during executor startup */
  PARTTARGET_EXEC,      /* want to prune during each plan node scan */
} PartClauseTarget;

/*
 * GeneratePruningStepsContext
 *    Information about the current state of generation of "pruning steps"
 *    for a given set of clauses
 *
 * gen_partprune_steps() initializes and returns an instance of this struct.
 *
 * Note that has_mutable_op, has_mutable_arg, and has_exec_param are set if
 * we found any potentially-useful-for-pruning clause having those properties,
 * whether or not we actually used the clause in the steps list.  This
 * definition allows us to skip the PARTTARGET_EXEC pass in some cases.
 */
typedef struct GeneratePruningStepsContext
{
  /* Copies of input arguments for gen_partprune_steps: */
  RelOptInfo *rel;      /* the partitioned relation */
  PartClauseTarget target;  /* use-case we're generating steps for */
  /* Result data: */
  List     *steps;      /* list of PartitionPruneSteps */
  bool    has_mutable_op; /* clauses include any stable operators */
  bool    has_mutable_arg;  /* clauses include any mutable comparison
                   * values, *other than* exec params */
  bool    has_exec_param; /* clauses include any PARAM_EXEC params */
  bool    contradictory;  /* clauses were proven self-contradictory */
  /* Working state: */
  int     next_step_id;
} GeneratePruningStepsContext;

/* The result of performing one PartitionPruneStep */
typedef struct PruneStepResult
{
  /*
   * The offsets of bounds (in a table's boundinfo) whose partition is
   * selected by the pruning step.
   */
  Bitmapset  *bound_offsets;

  bool    scan_default; /* Scan the default partition? */
  bool    scan_null;    /* Scan the partition for NULL values? */
} PruneStepResult;


static List *add_part_relids(List *allpartrelids, Bitmapset *partrelids);
static List *make_partitionedrel_pruneinfo(PlannerInfo *root,
                       RelOptInfo *parentrel,
                       List *prunequal,
                       Bitmapset *partrelids,
                       int *relid_subplan_map,
                       Bitmapset **matchedsubplans);
static void gen_partprune_steps(RelOptInfo *rel, List *clauses,
                PartClauseTarget target,
                GeneratePruningStepsContext *context);
static List *gen_partprune_steps_internal(GeneratePruningStepsContext *context,
                      List *clauses);
static PartitionPruneStep *gen_prune_step_op(GeneratePruningStepsContext *context,
                       StrategyNumber opstrategy, bool op_is_ne,
                       List *exprs, List *cmpfns, Bitmapset *nullkeys);
static PartitionPruneStep *gen_prune_step_combine(GeneratePruningStepsContext *context,
                          List *source_stepids,
                          PartitionPruneCombineOp combineOp);
static List *gen_prune_steps_from_opexps(GeneratePruningStepsContext *context,
                     List **keyclauses, Bitmapset *nullkeys);
static PartClauseMatchStatus match_clause_to_partition_key(GeneratePruningStepsContext *context,
                               Expr *clause, Expr *partkey, int partkeyidx,
                               bool *clause_is_not_null,
                               PartClauseInfo **pc, List **clause_steps);
static List *get_steps_using_prefix(GeneratePruningStepsContext *context,
                  StrategyNumber step_opstrategy,
                  bool step_op_is_ne,
                  Expr *step_lastexpr,
                  Oid step_lastcmpfn,
                  Bitmapset *step_nullkeys,
                  List *prefix);
static List *get_steps_using_prefix_recurse(GeneratePruningStepsContext *context,
                      StrategyNumber step_opstrategy,
                      bool step_op_is_ne,
                      Expr *step_lastexpr,
                      Oid step_lastcmpfn,
                      Bitmapset *step_nullkeys,
                      List *prefix,
                      ListCell *start,
                      List *step_exprs,
                      List *step_cmpfns);
static PruneStepResult *get_matching_hash_bounds(PartitionPruneContext *context,
                         StrategyNumber opstrategy, Datum *values, int nvalues,
                         FmgrInfo *partsupfunc, Bitmapset *nullkeys);
static PruneStepResult *get_matching_list_bounds(PartitionPruneContext *context,
                         StrategyNumber opstrategy, Datum value, int nvalues,
                         FmgrInfo *partsupfunc, Bitmapset *nullkeys);
static PruneStepResult *get_matching_range_bounds(PartitionPruneContext *context,
                          StrategyNumber opstrategy, Datum *values, int nvalues,
                          FmgrInfo *partsupfunc, Bitmapset *nullkeys);
static Bitmapset *pull_exec_paramids(Expr *expr);
static bool pull_exec_paramids_walker(Node *node, Bitmapset **context);
static Bitmapset *get_partkey_exec_paramids(List *steps);
static PruneStepResult *perform_pruning_base_step(PartitionPruneContext *context,
                          PartitionPruneStepOp *opstep);
static PruneStepResult *perform_pruning_combine_step(PartitionPruneContext *context,
                           PartitionPruneStepCombine *cstep,
                           PruneStepResult **step_results);
static PartClauseMatchStatus match_boolean_partition_clause(Oid partopfamily,
                              Expr *clause,
                              Expr *partkey,
                              Expr **outconst,
                              bool *notclause);
static void partkey_datum_from_expr(PartitionPruneContext *context,
                  Expr *expr, int stateidx,
                  Datum *value, bool *isnull);


/*
 * make_partition_pruneinfo
 *    Checks if the given set of quals can be used to build pruning steps
 *    that the executor can use to prune away unneeded partitions.  If
 *    suitable quals are found then a PartitionPruneInfo is built and tagged
 *    onto the PlannerInfo's partPruneInfos list.
 *
 * The return value is the 0-based index of the item added to the
 * partPruneInfos list or -1 if nothing was added.
 *
 * 'parentrel' is the RelOptInfo for an appendrel, and 'subpaths' is the list
 * of scan paths for its child rels.
 * 'prunequal' is a list of potential pruning quals (i.e., restriction
 * clauses that are applicable to the appendrel).
 */
int
make_partition_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
             List *subpaths,
             List *prunequal)
{
  PartitionPruneInfo *pruneinfo;
  Bitmapset  *allmatchedsubplans = NULL;
  List     *allpartrelids;
  List     *prunerelinfos;
  int      *relid_subplan_map;
  ListCell   *lc;
  int     i;

  /*
   * Scan the subpaths to see which ones are scans of partition child
   * relations, and identify their parent partitioned rels.  (Note: we must
   * restrict the parent partitioned rels to be parentrel or children of
   * parentrel, otherwise we couldn't translate prunequal to match.)
   *
   * Also construct a temporary array to map from partition-child-relation
   * relid to the index in 'subpaths' of the scan plan for that partition.
   * (Use of "subplan" rather than "subpath" is a bit of a misnomer, but
   * we'll let it stand.)  For convenience, we use 1-based indexes here, so
   * that zero can represent an un-filled array entry.
   */
  allpartrelids = NIL;
  relid_subplan_map = palloc0(sizeof(int) * root->simple_rel_array_size);

  i = 1;
  foreach(lc, subpaths)
  {
    Path     *path = (Path *) lfirst(lc);
    RelOptInfo *pathrel = path->parent;

    /* We don't consider partitioned joins here */
    if (pathrel->reloptkind == RELOPT_OTHER_MEMBER_REL)
    {
      RelOptInfo *prel = pathrel;
      Bitmapset  *partrelids = NULL;

      /*
       * Traverse up to the pathrel's topmost partitioned parent,
       * collecting parent relids as we go; but stop if we reach
       * parentrel.  (Normally, a pathrel's topmost partitioned parent
       * is either parentrel or a UNION ALL appendrel child of
       * parentrel.  But when handling partitionwise joins of
       * multi-level partitioning trees, we can see an append path whose
       * parentrel is an intermediate partitioned table.)
       */
      do
      {
        AppendRelInfo *appinfo;

        Assert(prel->relid < root->simple_rel_array_size);
        appinfo = root->append_rel_array[prel->relid];
        prel = find_base_rel(root, appinfo->parent_relid);
        if (!IS_PARTITIONED_REL(prel))
          break;   /* reached a non-partitioned parent */
        /* accept this level as an interesting parent */
        partrelids = bms_add_member(partrelids, prel->relid);
        if (prel == parentrel)
          break;   /* don't traverse above parentrel */
      } while (prel->reloptkind == RELOPT_OTHER_MEMBER_REL);

      if (partrelids)
      {
        /*
         * Found some relevant parent partitions, which may or may not
         * overlap with partition trees we already found.  Add new
         * information to the allpartrelids list.
         */
        allpartrelids = add_part_relids(allpartrelids, partrelids);
        /* Also record the subplan in relid_subplan_map[] */
        /* No duplicates please */
        Assert(relid_subplan_map[pathrel->relid] == 0);
        relid_subplan_map[pathrel->relid] = i;
      }
    }
    i++;
  }

  /*
   * We now build a PartitionedRelPruneInfo for each topmost partitioned rel
   * (omitting any that turn out not to have useful pruning quals).
   */
  prunerelinfos = NIL;
  foreach(lc, allpartrelids)
  {
    Bitmapset  *partrelids = (Bitmapset *) lfirst(lc);
    List     *pinfolist;
    Bitmapset  *matchedsubplans = NULL;

    pinfolist = make_partitionedrel_pruneinfo(root, parentrel,
                          prunequal,
                          partrelids,
                          relid_subplan_map,
                          &matchedsubplans);

    /* When pruning is possible, record the matched subplans */
    if (pinfolist != NIL)
    {
      prunerelinfos = lappend(prunerelinfos, pinfolist);
      allmatchedsubplans = bms_join(matchedsubplans,
                      allmatchedsubplans);
    }
  }

  pfree(relid_subplan_map);

  /*
   * If none of the partition hierarchies had any useful run-time pruning
   * quals, then we can just not bother with run-time pruning.
   */
  if (prunerelinfos == NIL)
    return -1;

  /* Else build the result data structure */
  pruneinfo = makeNode(PartitionPruneInfo);
  pruneinfo->relids = bms_copy(parentrel->relids);
  pruneinfo->prune_infos = prunerelinfos;

  /*
   * Some subplans may not belong to any of the identified partitioned rels.
   * This can happen for UNION ALL queries which include a non-partitioned
   * table, or when some of the hierarchies aren't run-time prunable.  Build
   * a bitmapset of the indexes of all such subplans, so that the executor
   * can identify which subplans should never be pruned.
   */
  if (bms_num_members(allmatchedsubplans) < list_length(subpaths))
  {
    Bitmapset  *other_subplans;

    /* Create the complement of allmatchedsubplans */
    other_subplans = bms_add_range(NULL, 0, list_length(subpaths) - 1);
    other_subplans = bms_del_members(other_subplans, allmatchedsubplans);

    pruneinfo->other_subplans = other_subplans;
  }
  else
    pruneinfo->other_subplans = NULL;

  root->partPruneInfos = lappend(root->partPruneInfos, pruneinfo);

  return list_length(root->partPruneInfos) - 1;
}

/*
 * add_part_relids
 *    Add new info to a list of Bitmapsets of partitioned relids.
 *
 * Within 'allpartrelids', there is one Bitmapset for each topmost parent
 * partitioned rel.  Each Bitmapset contains the RT indexes of the topmost
 * parent as well as its relevant non-leaf child partitions.  Since (by
 * construction of the rangetable list) parent partitions must have lower
 * RT indexes than their children, we can distinguish the topmost parent
 * as being the lowest set bit in the Bitmapset.
 *
 * 'partrelids' contains the RT indexes of a parent partitioned rel, and
 * possibly some non-leaf children, that are newly identified as parents of
 * some subpath rel passed to make_partition_pruneinfo().  These are added
 * to an appropriate member of 'allpartrelids'.
 *
 * Note that the list contains only RT indexes of partitioned tables that
 * are parents of some scan-level relation appearing in the 'subpaths' that
 * make_partition_pruneinfo() is dealing with.  Also, "topmost" parents are
 * not allowed to be higher than the 'parentrel' associated with the append
 * path.  In this way, we avoid expending cycles on partitioned rels that
 * can't contribute useful pruning information for the problem at hand.
 * (It is possible for 'parentrel' to be a child partitioned table, and it
 * is also possible for scan-level relations to be child partitioned tables
 * rather than leaf partitions.  Hence we must construct this relation set
 * with reference to the particular append path we're dealing with, rather
 * than looking at the full partitioning structure represented in the
 * RelOptInfos.)
 */
static List *
add_part_relids(List *allpartrelids, Bitmapset *partrelids)
{
  Index   targetpart;
  ListCell   *lc;

  /* We can easily get the lowest set bit this way: */
  targetpart = bms_next_member(partrelids, -1);
  Assert(targetpart > 0);

  /* Look for a matching topmost parent */
  foreach(lc, allpartrelids)
  {
    Bitmapset  *currpartrelids = (Bitmapset *) lfirst(lc);
    Index   currtarget = bms_next_member(currpartrelids, -1);

    if (targetpart == currtarget)
    {
      /* Found a match, so add any new RT indexes to this hierarchy */
      currpartrelids = bms_add_members(currpartrelids, partrelids);
      lfirst(lc) = currpartrelids;
      return allpartrelids;
    }
  }
  /* No match, so add the new partition hierarchy to the list */
  return lappend(allpartrelids, partrelids);
}

/*
 * make_partitionedrel_pruneinfo
 *    Build a List of PartitionedRelPruneInfos, one for each interesting
 *    partitioned rel in a partitioning hierarchy.  These can be used in the
 *    executor to allow additional partition pruning to take place.
 *
 * parentrel: rel associated with the appendpath being considered
 * prunequal: potential pruning quals, represented for parentrel
 * partrelids: Set of RT indexes identifying relevant partitioned tables
 *   within a single partitioning hierarchy
 * relid_subplan_map[]: maps child relation relids to subplan indexes
 * matchedsubplans: on success, receives the set of subplan indexes which
 *   were matched to this partition hierarchy
 *
 * If we cannot find any useful run-time pruning steps, return NIL.
 * However, on success, each rel identified in partrelids will have
 * an element in the result list, even if some of them are useless.
 */
static List *
make_partitionedrel_pruneinfo(PlannerInfo *root, RelOptInfo *parentrel,
                List *prunequal,
                Bitmapset *partrelids,
                int *relid_subplan_map,
                Bitmapset **matchedsubplans)
{
  RelOptInfo *targetpart = NULL;
  List     *pinfolist = NIL;
  bool    doruntimeprune = false;
  int      *relid_subpart_map;
  Bitmapset  *subplansfound = NULL;
  ListCell   *lc;
  int     rti;
  int     i;

  /*
   * Examine each partitioned rel, constructing a temporary array to map
   * from planner relids to index of the partitioned rel, and building a
   * PartitionedRelPruneInfo for each partitioned rel.
   *
   * In this phase we discover whether runtime pruning is needed at all; if
   * not, we can avoid doing further work.
   */
  relid_subpart_map = palloc0(sizeof(int) * root->simple_rel_array_size);

  i = 1;
  rti = -1;
  while ((rti = bms_next_member(partrelids, rti)) > 0)
  {
    RelOptInfo *subpart = find_base_rel(root, rti);
    PartitionedRelPruneInfo *pinfo;
    List     *partprunequal;
    List     *initial_pruning_steps;
    List     *exec_pruning_steps;
    Bitmapset  *execparamids;
    GeneratePruningStepsContext context;

    /*
     * Fill the mapping array.
     *
     * relid_subpart_map maps relid of a non-leaf partition to the index
     * in the returned PartitionedRelPruneInfo list of the info for that
     * partition.  We use 1-based indexes here, so that zero can represent
     * an un-filled array entry.
     */
    Assert(rti < root->simple_rel_array_size);
    relid_subpart_map[rti] = i++;

    /*
     * Translate pruning qual, if necessary, for this partition.
     *
     * The first item in the list is the target partitioned relation.
     */
    if (!targetpart)
    {
      targetpart = subpart;

      /*
       * The prunequal is presented to us as a qual for 'parentrel'.
       * Frequently this rel is the same as targetpart, so we can skip
       * an adjust_appendrel_attrs step.  But it might not be, and then
       * we have to translate.  We update the prunequal parameter here,
       * because in later iterations of the loop for child partitions,
       * we want to translate from parent to child variables.
       */
      if (!bms_equal(parentrel->relids, subpart->relids))
      {
        int     nappinfos;
        AppendRelInfo **appinfos = find_appinfos_by_relids(root,
                                   subpart->relids,
                                   &nappinfos);

        prunequal = (List *) adjust_appendrel_attrs(root, (Node *)
                              prunequal,
                              nappinfos,
                              appinfos);

        pfree(appinfos);
      }

      partprunequal = prunequal;
    }
    else
    {
      /*
       * For sub-partitioned tables the columns may not be in the same
       * order as the parent, so we must translate the prunequal to make
       * it compatible with this relation.
       */
      partprunequal = (List *)
        adjust_appendrel_attrs_multilevel(root,
                          (Node *) prunequal,
                          subpart,
                          targetpart);
    }

    /*
     * Convert pruning qual to pruning steps.  We may need to do this
     * twice, once to obtain executor startup pruning steps, and once for
     * executor per-scan pruning steps.  This first pass creates startup
     * pruning steps and detects whether there's any possibly-useful quals
     * that would require per-scan pruning.
     */
    gen_partprune_steps(subpart, partprunequal, PARTTARGET_INITIAL,
              &context);

    if (context.contradictory)
    {
      /*
       * This shouldn't happen as the planner should have detected this
       * earlier. However, we do use additional quals from parameterized
       * paths here. These do only compare Params to the partition key,
       * so this shouldn't cause the discovery of any new qual
       * contradictions that were not previously discovered as the Param
       * values are unknown during planning.  Anyway, we'd better do
       * something sane here, so let's just disable run-time pruning.
       */
      return NIL;
    }

    /*
     * If no mutable operators or expressions appear in usable pruning
     * clauses, then there's no point in running startup pruning, because
     * plan-time pruning should have pruned everything prunable.
     */
    if (context.has_mutable_op || context.has_mutable_arg)
      initial_pruning_steps = context.steps;
    else
      initial_pruning_steps = NIL;

    /*
     * If no exec Params appear in potentially-usable pruning clauses,
     * then there's no point in even thinking about per-scan pruning.
     */
    if (context.has_exec_param)
    {
      /* ... OK, we'd better think about it */
      gen_partprune_steps(subpart, partprunequal, PARTTARGET_EXEC,
                &context);

      if (context.contradictory)
      {
        /* As above, skip run-time pruning if anything fishy happens */
        return NIL;
      }

      exec_pruning_steps = context.steps;

      /*
       * Detect which exec Params actually got used; the fact that some
       * were in available clauses doesn't mean we actually used them.
       * Skip per-scan pruning if there are none.
       */
      execparamids = get_partkey_exec_paramids(exec_pruning_steps);

      if (bms_is_empty(execparamids))
        exec_pruning_steps = NIL;
    }
    else
    {
      /* No exec Params anywhere, so forget about scan-time pruning */
      exec_pruning_steps = NIL;
      execparamids = NULL;
    }

    if (initial_pruning_steps || exec_pruning_steps)
      doruntimeprune = true;

    /* Begin constructing the PartitionedRelPruneInfo for this rel */
    pinfo = makeNode(PartitionedRelPruneInfo);
    pinfo->rtindex = rti;
    pinfo->initial_pruning_steps = initial_pruning_steps;
    pinfo->exec_pruning_steps = exec_pruning_steps;
    pinfo->execparamids = execparamids;
    /* Remaining fields will be filled in the next loop */

    pinfolist = lappend(pinfolist, pinfo);
  }

  if (!doruntimeprune)
  {
    /* No run-time pruning required. */
    pfree(relid_subpart_map);
    return NIL;
  }

  /*
   * Run-time pruning will be required, so initialize other information.
   * That includes two maps -- one needed to convert partition indexes of
   * leaf partitions to the indexes of their subplans in the subplan list,
   * another needed to convert partition indexes of sub-partitioned
   * partitions to the indexes of their PartitionedRelPruneInfo in the
   * PartitionedRelPruneInfo list.
   */
  foreach(lc, pinfolist)
  {
    PartitionedRelPruneInfo *pinfo = lfirst(lc);
    RelOptInfo *subpart = find_base_rel(root, pinfo->rtindex);
    Bitmapset  *present_parts;
    int     nparts = subpart->nparts;
    int      *subplan_map;
    int      *subpart_map;
    Oid      *relid_map;
    int      *leafpart_rti_map;

    /*
     * Construct the subplan and subpart maps for this partitioning level.
     * Here we convert to zero-based indexes, with -1 for empty entries.
     * Also construct a Bitmapset of all partitions that are present (that
     * is, not pruned already).
     */
    subplan_map = (int *) palloc(nparts * sizeof(int));
    memset(subplan_map, -1, nparts * sizeof(int));
    subpart_map = (int *) palloc(nparts * sizeof(int));
    memset(subpart_map, -1, nparts * sizeof(int));
    relid_map = (Oid *) palloc0(nparts * sizeof(Oid));
    leafpart_rti_map = (int *) palloc0(nparts * sizeof(int));
    present_parts = NULL;

    i = -1;
    while ((i = bms_next_member(subpart->live_parts, i)) >= 0)
    {
      RelOptInfo *partrel = subpart->part_rels[i];
      int     subplanidx;
      int     subpartidx;

      Assert(partrel != NULL);

      subplan_map[i] = subplanidx = relid_subplan_map[partrel->relid] - 1;
      subpart_map[i] = subpartidx = relid_subpart_map[partrel->relid] - 1;
      relid_map[i] = planner_rt_fetch(partrel->relid, root)->relid;

      /*
       * Track the RT indexes of "leaf" partitions so they can be
       * included in the PlannerGlobal.prunableRelids set, indicating
       * relations that may be pruned during executor startup.
       *
       * Only leaf partitions with a valid subplan that are prunable
       * using initial pruning are added to prunableRelids. So
       * partitions without a subplan due to constraint exclusion will
       * remain in PlannedStmt.unprunableRelids.
       */
      if (subplanidx >= 0)
      {
        present_parts = bms_add_member(present_parts, i);

        /*
         * Non-leaf partitions may appear here when they use an
         * unflattened Append or MergeAppend. These should not be
         * included in prunableRelids.
         */
        if (partrel->nparts == -1)
          leafpart_rti_map[i] = (int) partrel->relid;

        /* Record finding this subplan  */
        subplansfound = bms_add_member(subplansfound, subplanidx);
      }
      else if (subpartidx >= 0)
        present_parts = bms_add_member(present_parts, i);
    }

    /*
     * Ensure there were no stray PartitionedRelPruneInfo generated for
     * partitioned tables that we have no sub-paths or
     * sub-PartitionedRelPruneInfo for.
     */
    Assert(!bms_is_empty(present_parts));

    /* Record the maps and other information. */
    pinfo->present_parts = present_parts;
    pinfo->nparts = nparts;
    pinfo->subplan_map = subplan_map;
    pinfo->subpart_map = subpart_map;
    pinfo->relid_map = relid_map;
    pinfo->leafpart_rti_map = leafpart_rti_map;
  }

  pfree(relid_subpart_map);

  *matchedsubplans = subplansfound;

  return pinfolist;
}

/*
 * gen_partprune_steps
 *    Process 'clauses' (typically a rel's baserestrictinfo list of clauses)
 *    and create a list of "partition pruning steps".
 *
 * 'target' tells whether to generate pruning steps for planning (use
 * immutable clauses only), or for executor startup (use any allowable
 * clause except ones containing PARAM_EXEC Params), or for executor
 * per-scan pruning (use any allowable clause).
 *
 * 'context' is an output argument that receives the steps list as well as
 * some subsidiary flags; see the GeneratePruningStepsContext typedef.
 */
static void
gen_partprune_steps(RelOptInfo *rel, List *clauses, PartClauseTarget target,
          GeneratePruningStepsContext *context)
{
  /* Initialize all output values to zero/false/NULL */
  memset(context, 0, sizeof(GeneratePruningStepsContext));
  context->rel = rel;
  context->target = target;

  /*
   * If this partitioned table is in turn a partition, and it shares any
   * partition keys with its parent, then it's possible that the hierarchy
   * allows the parent a narrower range of values than some of its
   * partitions (particularly the default one).  This is normally not
   * useful, but it can be to prune the default partition.
   */
  if (partition_bound_has_default(rel->boundinfo) && rel->partition_qual)
  {
    /* Make a copy to avoid modifying the passed-in List */
    clauses = list_concat_copy(clauses, rel->partition_qual);
  }

  /* Down into the rabbit-hole. */
  (void) gen_partprune_steps_internal(context, clauses);
}

/*
 * prune_append_rel_partitions
 *    Process rel's baserestrictinfo and make use of quals which can be
 *    evaluated during query planning in order to determine the minimum set
 *    of partitions which must be scanned to satisfy these quals.  Returns
 *    the matching partitions in the form of a Bitmapset containing the
 *    partitions' indexes in the rel's part_rels array.
 *
 * Callers must ensure that 'rel' is a partitioned table.
 */
Bitmapset *
prune_append_rel_partitions(RelOptInfo *rel)
{
  List     *clauses = rel->baserestrictinfo;
  List     *pruning_steps;
  GeneratePruningStepsContext gcontext;
  PartitionPruneContext context;

  Assert(rel->part_scheme != NULL);

  /* If there are no partitions, return the empty set */
  if (rel->nparts == 0)
    return NULL;

  /*
   * If pruning is disabled or if there are no clauses to prune with, return
   * all partitions.
   */
  if (!enable_partition_pruning || clauses == NIL)
    return bms_add_range(NULL, 0, rel->nparts - 1);

  /*
   * Process clauses to extract pruning steps that are usable at plan time.
   * If the clauses are found to be contradictory, we can return the empty
   * set.
   */
  gen_partprune_steps(rel, clauses, PARTTARGET_PLANNER,
            &gcontext);
  if (gcontext.contradictory)
    return NULL;
  pruning_steps = gcontext.steps;

  /* If there's nothing usable, return all partitions */
  if (pruning_steps == NIL)
    return bms_add_range(NULL, 0, rel->nparts - 1);

  /* Set up PartitionPruneContext */
  context.strategy = rel->part_scheme->strategy;
  context.partnatts = rel->part_scheme->partnatts;
  context.nparts = rel->nparts;
  context.boundinfo = rel->boundinfo;
  context.partcollation = rel->part_scheme->partcollation;
  context.partsupfunc = rel->part_scheme->partsupfunc;
  context.stepcmpfuncs = (FmgrInfo *) palloc0(sizeof(FmgrInfo) *
                        context.partnatts *
                        list_length(pruning_steps));
  context.ppccontext = CurrentMemoryContext;

  /* These are not valid when being called from the planner */
  context.planstate = NULL;
  context.exprcontext = NULL;
  context.exprstates = NULL;

  /* Actual pruning happens here. */
  return get_matching_partitions(&context, pruning_steps);
}

/*
 * get_matching_partitions
 *    Determine partitions that survive partition pruning
 *
 * Note: context->exprcontext must be valid when the pruning_steps were
 * generated with a target other than PARTTARGET_PLANNER.
 *
 * Returns a Bitmapset of the RelOptInfo->part_rels indexes of the surviving
 * partitions.
 */
Bitmapset *
get_matching_partitions(PartitionPruneContext *context, List *pruning_steps)
{
  Bitmapset  *result;
  int     num_steps = list_length(pruning_steps),
        i;
  PruneStepResult **results,
         *final_result;
  ListCell   *lc;
  bool    scan_default;

  /* If there are no pruning steps then all partitions match. */
  if (num_steps == 0)
  {
    Assert(context->nparts > 0);
    return bms_add_range(NULL, 0, context->nparts - 1);
  }

  /*
   * Allocate space for individual pruning steps to store its result.  Each
   * slot will hold a PruneStepResult after performing a given pruning step.
   * Later steps may use the result of one or more earlier steps.  The
   * result of applying all pruning steps is the value contained in the slot
   * of the last pruning step.
   */
  results = (PruneStepResult **)
    palloc0(num_steps * sizeof(PruneStepResult *));
  foreach(lc, pruning_steps)
  {
    PartitionPruneStep *step = lfirst(lc);

    switch (nodeTag(step))
    {
      case T_PartitionPruneStepOp:
        results[step->step_id] =
          perform_pruning_base_step(context,
                        (PartitionPruneStepOp *) step);
        break;

      case T_PartitionPruneStepCombine:
        results[step->step_id] =
          perform_pruning_combine_step(context,
                         (PartitionPruneStepCombine *) step,
                         results);
        break;

      default:
        elog(ERROR, "invalid pruning step type: %d",
           (int) nodeTag(step));
    }
  }

  /*
   * At this point we know the offsets of all the datums whose corresponding
   * partitions need to be in the result, including special null-accepting
   * and default partitions.  Collect the actual partition indexes now.
   */
  final_result = results[num_steps - 1];
  Assert(final_result != NULL);
  i = -1;
  result = NULL;
  scan_default = final_result->scan_default;
  while ((i = bms_next_member(final_result->bound_offsets, i)) >= 0)
  {
    int     partindex;

    Assert(i < context->boundinfo->nindexes);
    partindex = context->boundinfo->indexes[i];

    if (partindex < 0)
    {
      /*
       * In range partitioning cases, if a partition index is -1 it
       * means that the bound at the offset is the upper bound for a
       * range not covered by any partition (other than a possible
       * default partition).  In hash partitioning, the same means no
       * partition has been defined for the corresponding remainder
       * value.
       *
       * In either case, the value is still part of the queried range of
       * values, so mark to scan the default partition if one exists.
       */
      scan_default |= partition_bound_has_default(context->boundinfo);
      continue;
    }

    result = bms_add_member(result, partindex);
  }

  /* Add the null and/or default partition if needed and present. */
  if (final_result->scan_null)
  {
    Assert(context->strategy == PARTITION_STRATEGY_LIST);
    Assert(partition_bound_accepts_nulls(context->boundinfo));
    result = bms_add_member(result, context->boundinfo->null_index);
  }
  if (scan_default)
  {
    Assert(context->strategy == PARTITION_STRATEGY_LIST ||
         context->strategy == PARTITION_STRATEGY_RANGE);
    Assert(partition_bound_has_default(context->boundinfo));
    result = bms_add_member(result, context->boundinfo->default_index);
  }

  return result;
}

/*
 * gen_partprune_steps_internal
 *    Processes 'clauses' to generate a List of partition pruning steps.  We
 *    return NIL when no steps were generated.
 *
 * These partition pruning steps come in 2 forms; operator steps and combine
 * steps.
 *
 * Operator steps (PartitionPruneStepOp) contain details of clauses that we
 * determined that we can use for partition pruning.  These contain details of
 * the expression which is being compared to the partition key and the
 * comparison function.
 *
 * Combine steps (PartitionPruneStepCombine) instruct the partition pruning
 * code how it should produce a single set of partitions from multiple input
 * operator and other combine steps.  A PARTPRUNE_COMBINE_INTERSECT type
 * combine step will merge its input steps to produce a result which only
 * contains the partitions which are present in all of the input operator
 * steps.  A PARTPRUNE_COMBINE_UNION combine step will produce a result that
 * has all of the partitions from each of the input operator steps.
 *
 * For BoolExpr clauses, each argument is processed recursively. Steps
 * generated from processing an OR BoolExpr will be combined using
 * PARTPRUNE_COMBINE_UNION.  AND BoolExprs get combined using
 * PARTPRUNE_COMBINE_INTERSECT.
 *
 * Otherwise, the list of clauses we receive we assume to be mutually ANDed.
 * We generate all of the pruning steps we can based on these clauses and then
 * at the end, if we have more than 1 step, we combine each step with a
 * PARTPRUNE_COMBINE_INTERSECT combine step.  Single steps are returned as-is.
 *
 * If we find clauses that are mutually contradictory, or contradictory with
 * the partitioning constraint, or a pseudoconstant clause that contains
 * false, we set context->contradictory to true and return NIL (that is, no
 * pruning steps).  Caller should consider all partitions as pruned in that
 * case.
 */
static List *
gen_partprune_steps_internal(GeneratePruningStepsContext *context,
               List *clauses)
{
  PartitionScheme part_scheme = context->rel->part_scheme;
  List     *keyclauses[PARTITION_MAX_KEYS];
  Bitmapset  *nullkeys = NULL,
         *notnullkeys = NULL;
  bool    generate_opsteps = false;
  List     *result = NIL;
  ListCell   *lc;

  /*
   * If this partitioned relation has a default partition and is itself a
   * partition (as evidenced by partition_qual being not NIL), we first
   * check if the clauses contradict the partition constraint.  If they do,
   * there's no need to generate any steps as it'd already be proven that no
   * partitions need to be scanned.
   *
   * This is a measure of last resort only to be used because the default
   * partition cannot be pruned using the steps generated from clauses that
   * contradict the parent's partition constraint; regular pruning, which is
   * cheaper, is sufficient when no default partition exists.
   */
  if (partition_bound_has_default(context->rel->boundinfo) &&
    predicate_refuted_by(context->rel->partition_qual, clauses, false))
  {
    context->contradictory = true;
    return NIL;
  }

  memset(keyclauses, 0, sizeof(keyclauses));
  foreach(lc, clauses)
  {
    Expr     *clause = (Expr *) lfirst(lc);
    int     i;

    /* Look through RestrictInfo, if any */
    if (IsA(clause, RestrictInfo))
      clause = ((RestrictInfo *) clause)->clause;

    /* Constant-false-or-null is contradictory */
    if (IsA(clause, Const) &&
      (((Const *) clause)->constisnull ||
       !DatumGetBool(((Const *) clause)->constvalue)))
    {
      context->contradictory = true;
      return NIL;
    }

    /* Get the BoolExpr's out of the way. */
    if (IsA(clause, BoolExpr))
    {
      /*
       * Generate steps for arguments.
       *
       * While steps generated for the arguments themselves will be
       * added to context->steps during recursion and will be evaluated
       * independently, collect their step IDs to be stored in the
       * combine step we'll be creating.
       */
      if (is_orclause(clause))
      {
        List     *arg_stepids = NIL;
        bool    all_args_contradictory = true;
        ListCell   *lc1;

        /*
         * We can share the outer context area with the recursive
         * call, but contradictory had better not be true yet.
         */
        Assert(!context->contradictory);

        /*
         * Get pruning step for each arg.  If we get contradictory for
         * all args, it means the OR expression is false as a whole.
         */
        foreach(lc1, ((BoolExpr *) clause)->args)
        {
          Expr     *arg = lfirst(lc1);
          bool    arg_contradictory;
          List     *argsteps;

          argsteps = gen_partprune_steps_internal(context,
                              list_make1(arg));
          arg_contradictory = context->contradictory;
          /* Keep context->contradictory clear till we're done */
          context->contradictory = false;

          if (arg_contradictory)
          {
            /* Just ignore self-contradictory arguments. */
            continue;
          }
          else
            all_args_contradictory = false;

          if (argsteps != NIL)
          {
            /*
             * gen_partprune_steps_internal() always adds a single
             * combine step when it generates multiple steps, so
             * here we can just pay attention to the last one in
             * the list.  If it just generated one, then the last
             * one in the list is still the one we want.
             */
            PartitionPruneStep *last = llast(argsteps);

            arg_stepids = lappend_int(arg_stepids, last->step_id);
          }
          else
          {
            PartitionPruneStep *orstep;

            /*
             * The arg didn't contain a clause matching this
             * partition key.  We cannot prune using such an arg.
             * To indicate that to the pruning code, we must
             * construct a dummy PartitionPruneStepCombine whose
             * source_stepids is set to an empty List.
             */
            orstep = gen_prune_step_combine(context, NIL,
                            PARTPRUNE_COMBINE_UNION);
            arg_stepids = lappend_int(arg_stepids, orstep->step_id);
          }
        }

        /* If all the OR arms are contradictory, we can stop */
        if (all_args_contradictory)
        {
          context->contradictory = true;
          return NIL;
        }

        if (arg_stepids != NIL)
        {
          PartitionPruneStep *step;

          step = gen_prune_step_combine(context, arg_stepids,
                          PARTPRUNE_COMBINE_UNION);
          result = lappend(result, step);
        }
        continue;
      }
      else if (is_andclause(clause))
      {
        List     *args = ((BoolExpr *) clause)->args;
        List     *argsteps;

        /*
         * args may itself contain clauses of arbitrary type, so just
         * recurse and later combine the component partitions sets
         * using a combine step.
         */
        argsteps = gen_partprune_steps_internal(context, args);

        /* If any AND arm is contradictory, we can stop immediately */
        if (context->contradictory)
          return NIL;

        /*
         * gen_partprune_steps_internal() always adds a single combine
         * step when it generates multiple steps, so here we can just
         * pay attention to the last one in the list.  If it just
         * generated one, then the last one in the list is still the
         * one we want.
         */
        if (argsteps != NIL)
          result = lappend(result, llast(argsteps));

        continue;
      }

      /*
       * Fall-through for a NOT clause, which if it's a Boolean clause,
       * will be handled in match_clause_to_partition_key(). We
       * currently don't perform any pruning for more complex NOT
       * clauses.
       */
    }

    /*
     * See if we can match this clause to any of the partition keys.
     */
    for (i = 0; i < part_scheme->partnatts; i++)
    {
      Expr     *partkey = linitial(context->rel->partexprs[i]);
      bool    clause_is_not_null = false;
      PartClauseInfo *pc = NULL;
      List     *clause_steps = NIL;

      switch (match_clause_to_partition_key(context,
                          clause, partkey, i,
                          &clause_is_not_null,
                          &pc, &clause_steps))
      {
        case PARTCLAUSE_MATCH_CLAUSE:
          Assert(pc != NULL);

          /*
           * Since we only allow strict operators, check for any
           * contradicting IS NULL.
           */
          if (bms_is_member(i, nullkeys))
          {
            context->contradictory = true;
            return NIL;
          }
          generate_opsteps = true;
          keyclauses[i] = lappend(keyclauses[i], pc);
          break;

        case PARTCLAUSE_MATCH_NULLNESS:
          if (!clause_is_not_null)
          {
            /*
             * check for conflicting IS NOT NULL as well as
             * contradicting strict clauses
             */
            if (bms_is_member(i, notnullkeys) ||
              keyclauses[i] != NIL)
            {
              context->contradictory = true;
              return NIL;
            }
            nullkeys = bms_add_member(nullkeys, i);
          }
          else
          {
            /* check for conflicting IS NULL */
            if (bms_is_member(i, nullkeys))
            {
              context->contradictory = true;
              return NIL;
            }
            notnullkeys = bms_add_member(notnullkeys, i);
          }
          break;

        case PARTCLAUSE_MATCH_STEPS:
          Assert(clause_steps != NIL);
          result = list_concat(result, clause_steps);
          break;

        case PARTCLAUSE_MATCH_CONTRADICT:
          /* We've nothing more to do if a contradiction was found. */
          context->contradictory = true;
          return NIL;

        case PARTCLAUSE_NOMATCH:

          /*
           * Clause didn't match this key, but it might match the
           * next one.
           */
          continue;

        case PARTCLAUSE_UNSUPPORTED:
          /* This clause cannot be used for pruning. */
          break;
      }

      /* done; go check the next clause. */
      break;
    }
  }

  /*-----------
   * Now generate some (more) pruning steps.  We have three strategies:
   *
   * 1) Generate pruning steps based on IS NULL clauses:
   *   a) For list partitioning, null partition keys can only be found in
   *      the designated null-accepting partition, so if there are IS NULL
   *      clauses containing partition keys we should generate a pruning
   *      step that gets rid of all partitions but that one.  We can
   *      disregard any OpExpr we may have found.
   *   b) For range partitioning, only the default partition can contain
   *      NULL values, so the same rationale applies.
   *   c) For hash partitioning, we only apply this strategy if we have
   *      IS NULL clauses for all the keys.  Strategy 2 below will take
   *      care of the case where some keys have OpExprs and others have
   *      IS NULL clauses.
   *
   * 2) If not, generate steps based on OpExprs we have (if any).
   *
   * 3) If this doesn't work either, we may be able to generate steps to
   *    prune just the null-accepting partition (if one exists), if we have
   *    IS NOT NULL clauses for all partition keys.
   */
  if (!bms_is_empty(nullkeys) &&
    (part_scheme->strategy == PARTITION_STRATEGY_LIST ||
     part_scheme->strategy == PARTITION_STRATEGY_RANGE ||
     (part_scheme->strategy == PARTITION_STRATEGY_HASH &&
      bms_num_members(nullkeys) == part_scheme->partnatts)))
  {
    PartitionPruneStep *step;

    /* Strategy 1 */
    step = gen_prune_step_op(context, InvalidStrategy,
                 false, NIL, NIL, nullkeys);
    result = lappend(result, step);
  }
  else if (generate_opsteps)
  {
    List     *opsteps;

    /* Strategy 2 */
    opsteps = gen_prune_steps_from_opexps(context, keyclauses, nullkeys);
    result = list_concat(result, opsteps);
  }
  else if (bms_num_members(notnullkeys) == part_scheme->partnatts)
  {
    PartitionPruneStep *step;

    /* Strategy 3 */
    step = gen_prune_step_op(context, InvalidStrategy,
                 false, NIL, NIL, NULL);
    result = lappend(result, step);
  }

  /*
   * Finally, if there are multiple steps, since the 'clauses' are mutually
   * ANDed, add an INTERSECT step to combine the partition sets resulting
   * from them and append it to the result list.
   */
  if (list_length(result) > 1)
  {
    List     *step_ids = NIL;
    PartitionPruneStep *final;

    foreach(lc, result)
    {
      PartitionPruneStep *step = lfirst(lc);

      step_ids = lappend_int(step_ids, step->step_id);
    }

    final = gen_prune_step_combine(context, step_ids,
                     PARTPRUNE_COMBINE_INTERSECT);
    result = lappend(result, final);
  }

  return result;
}

/*
 * gen_prune_step_op
 *    Generate a pruning step for a specific operator
 *
 * The step is assigned a unique step identifier and added to context's 'steps'
 * list.
 */
static PartitionPruneStep *
gen_prune_step_op(GeneratePruningStepsContext *context,
          StrategyNumber opstrategy, bool op_is_ne,
          List *exprs, List *cmpfns,
          Bitmapset *nullkeys)
{
  PartitionPruneStepOp *opstep = makeNode(PartitionPruneStepOp);

  opstep->step.step_id = context->next_step_id++;

  /*
   * For clauses that contain an <> operator, set opstrategy to
   * InvalidStrategy to signal get_matching_list_bounds to do the right
   * thing.
   */
  opstep->opstrategy = op_is_ne ? InvalidStrategy : opstrategy;
  Assert(list_length(exprs) == list_length(cmpfns));
  opstep->exprs = exprs;
  opstep->cmpfns = cmpfns;
  opstep->nullkeys = nullkeys;

  context->steps = lappend(context->steps, opstep);

  return (PartitionPruneStep *) opstep;
}

/*
 * gen_prune_step_combine
 *    Generate a pruning step for a combination of several other steps
 *
 * The step is assigned a unique step identifier and added to context's
 * 'steps' list.
 */
static PartitionPruneStep *
gen_prune_step_combine(GeneratePruningStepsContext *context,
             List *source_stepids,
             PartitionPruneCombineOp combineOp)
{
  PartitionPruneStepCombine *cstep = makeNode(PartitionPruneStepCombine);

  cstep->step.step_id = context->next_step_id++;
  cstep->combineOp = combineOp;
  cstep->source_stepids = source_stepids;

  context->steps = lappend(context->steps, cstep);

  return (PartitionPruneStep *) cstep;
}

/*
 * gen_prune_steps_from_opexps
 *    Generate and return a list of PartitionPruneStepOp that are based on
 *    OpExpr and BooleanTest clauses that have been matched to the partition
 *    key.
 *
 * 'keyclauses' is an array of List pointers, indexed by the partition key's
 * index.  Each List element in the array can contain clauses that match to
 * the corresponding partition key column.  Partition key columns without any
 * matched clauses will have an empty List.
 *
 * Some partitioning strategies allow pruning to still occur when we only have
 * clauses for a prefix of the partition key columns, for example, RANGE
 * partitioning.  Other strategies, such as HASH partitioning, require clauses
 * for all partition key columns.
 *
 * When we return multiple pruning steps here, it's up to the caller to add a
 * relevant "combine" step to combine the returned steps.  This is not done
 * here as callers may wish to include additional pruning steps before
 * combining them all.
 */
static List *
gen_prune_steps_from_opexps(GeneratePruningStepsContext *context,
              List **keyclauses, Bitmapset *nullkeys)
{
  PartitionScheme part_scheme = context->rel->part_scheme;
  List     *opsteps = NIL;
  List     *btree_clauses[BTMaxStrategyNumber + 1],
         *hash_clauses[HTMaxStrategyNumber + 1];
  int     i;
  ListCell   *lc;

  memset(btree_clauses, 0, sizeof(btree_clauses));
  memset(hash_clauses, 0, sizeof(hash_clauses));
  for (i = 0; i < part_scheme->partnatts; i++)
  {
    List     *clauselist = keyclauses[i];
    bool    consider_next_key = true;

    /*
     * For range partitioning, if we have no clauses for the current key,
     * we can't consider any later keys either, so we can stop here.
     */
    if (part_scheme->strategy == PARTITION_STRATEGY_RANGE &&
      clauselist == NIL)
      break;

    /*
     * For hash partitioning, if a column doesn't have the necessary
     * equality clause, there should be an IS NULL clause, otherwise
     * pruning is not possible.
     */
    if (part_scheme->strategy == PARTITION_STRATEGY_HASH &&
      clauselist == NIL && !bms_is_member(i, nullkeys))
      return NIL;

    foreach(lc, clauselist)
    {
      PartClauseInfo *pc = (PartClauseInfo *) lfirst(lc);
      Oid     lefttype,
            righttype;

      /* Look up the operator's btree/hash strategy number. */
      if (pc->op_strategy == InvalidStrategy)
        get_op_opfamily_properties(pc->opno,
                       part_scheme->partopfamily[i],
                       false,
                       &pc->op_strategy,
                       &lefttype,
                       &righttype);

      switch (part_scheme->strategy)
      {
        case PARTITION_STRATEGY_LIST:
        case PARTITION_STRATEGY_RANGE:
          btree_clauses[pc->op_strategy] =
            lappend(btree_clauses[pc->op_strategy], pc);

          /*
           * We can't consider subsequent partition keys if the
           * clause for the current key contains a non-inclusive
           * operator.
           */
          if (pc->op_strategy == BTLessStrategyNumber ||
            pc->op_strategy == BTGreaterStrategyNumber)
            consider_next_key = false;
          break;

        case PARTITION_STRATEGY_HASH:
          if (pc->op_strategy != HTEqualStrategyNumber)
            elog(ERROR, "invalid clause for hash partitioning");
          hash_clauses[pc->op_strategy] =
            lappend(hash_clauses[pc->op_strategy], pc);
          break;

        default:
          elog(ERROR, "invalid partition strategy: %c",
             part_scheme->strategy);
          break;
      }
    }

    /*
     * If we've decided that clauses for subsequent partition keys
     * wouldn't be useful for pruning, don't search any further.
     */
    if (!consider_next_key)
      break;
  }

  /*
   * Now, we have divided clauses according to their operator strategies.
   * Check for each strategy if we can generate pruning step(s) by
   * collecting a list of expressions whose values will constitute a vector
   * that can be used as a lookup key by a partition bound searching
   * function.
   */
  switch (part_scheme->strategy)
  {
    case PARTITION_STRATEGY_LIST:
    case PARTITION_STRATEGY_RANGE:
      {
        List     *eq_clauses = btree_clauses[BTEqualStrategyNumber];
        List     *le_clauses = btree_clauses[BTLessEqualStrategyNumber];
        List     *ge_clauses = btree_clauses[BTGreaterEqualStrategyNumber];
        int     strat;

        /*
         * For each clause under consideration for a given strategy,
         * we collect expressions from clauses for earlier keys, whose
         * operator strategy is inclusive, into a list called
         * 'prefix'. By appending the clause's own expression to the
         * 'prefix', we'll generate one step using the so generated
         * vector and assign the current strategy to it.  Actually,
         * 'prefix' might contain multiple clauses for the same key,
         * in which case, we must generate steps for various
         * combinations of expressions of different keys, which
         * get_steps_using_prefix takes care of for us.
         */
        for (strat = 1; strat <= BTMaxStrategyNumber; strat++)
        {
          foreach(lc, btree_clauses[strat])
          {
            PartClauseInfo *pc = lfirst(lc);
            ListCell   *eq_start;
            ListCell   *le_start;
            ListCell   *ge_start;
            ListCell   *lc1;
            List     *prefix = NIL;
            List     *pc_steps;
            bool    prefix_valid = true;
            bool    pk_has_clauses;
            int     keyno;

            /*
             * If this is a clause for the first partition key,
             * there are no preceding expressions; generate a
             * pruning step without a prefix.
             *
             * Note that we pass NULL for step_nullkeys, because
             * we don't search list/range partition bounds where
             * some keys are NULL.
             */
            if (pc->keyno == 0)
            {
              Assert(pc->op_strategy == strat);
              pc_steps = get_steps_using_prefix(context, strat,
                                pc->op_is_ne,
                                pc->expr,
                                pc->cmpfn,
                                NULL,
                                NIL);
              opsteps = list_concat(opsteps, pc_steps);
              continue;
            }

            eq_start = list_head(eq_clauses);
            le_start = list_head(le_clauses);
            ge_start = list_head(ge_clauses);

            /*
             * We arrange clauses into prefix in ascending order
             * of their partition key numbers.
             */
            for (keyno = 0; keyno < pc->keyno; keyno++)
            {
              pk_has_clauses = false;

              /*
               * Expressions from = clauses can always be in the
               * prefix, provided they're from an earlier key.
               */
              for_each_cell(lc1, eq_clauses, eq_start)
              {
                PartClauseInfo *eqpc = lfirst(lc1);

                if (eqpc->keyno == keyno)
                {
                  prefix = lappend(prefix, eqpc);
                  pk_has_clauses = true;
                }
                else
                {
                  Assert(eqpc->keyno > keyno);
                  break;
                }
              }
              eq_start = lc1;

              /*
               * If we're generating steps for </<= strategy, we
               * can add other <= clauses to the prefix,
               * provided they're from an earlier key.
               */
              if (strat == BTLessStrategyNumber ||
                strat == BTLessEqualStrategyNumber)
              {
                for_each_cell(lc1, le_clauses, le_start)
                {
                  PartClauseInfo *lepc = lfirst(lc1);

                  if (lepc->keyno == keyno)
                  {
                    prefix = lappend(prefix, lepc);
                    pk_has_clauses = true;
                  }
                  else
                  {
                    Assert(lepc->keyno > keyno);
                    break;
                  }
                }
                le_start = lc1;
              }

              /*
               * If we're generating steps for >/>= strategy, we
               * can add other >= clauses to the prefix,
               * provided they're from an earlier key.
               */
              if (strat == BTGreaterStrategyNumber ||
                strat == BTGreaterEqualStrategyNumber)
              {
                for_each_cell(lc1, ge_clauses, ge_start)
                {
                  PartClauseInfo *gepc = lfirst(lc1);

                  if (gepc->keyno == keyno)
                  {
                    prefix = lappend(prefix, gepc);
                    pk_has_clauses = true;
                  }
                  else
                  {
                    Assert(gepc->keyno > keyno);
                    break;
                  }
                }
                ge_start = lc1;
              }

              /*
               * If this key has no clauses, prefix is not valid
               * anymore.
               */
              if (!pk_has_clauses)
              {
                prefix_valid = false;
                break;
              }
            }

            /*
             * If prefix_valid, generate PartitionPruneStepOps.
             * Otherwise, we would not find clauses for a valid
             * subset of the partition keys anymore for the
             * strategy; give up on generating partition pruning
             * steps further for the strategy.
             *
             * As mentioned above, if 'prefix' contains multiple
             * expressions for the same key, the following will
             * generate multiple steps, one for each combination
             * of the expressions for different keys.
             *
             * Note that we pass NULL for step_nullkeys, because
             * we don't search list/range partition bounds where
             * some keys are NULL.
             */
            if (prefix_valid)
            {
              Assert(pc->op_strategy == strat);
              pc_steps = get_steps_using_prefix(context, strat,
                                pc->op_is_ne,
                                pc->expr,
                                pc->cmpfn,
                                NULL,
                                prefix);
              opsteps = list_concat(opsteps, pc_steps);
            }
            else
              break;
          }
        }
        break;
      }

    case PARTITION_STRATEGY_HASH:
      {
        List     *eq_clauses = hash_clauses[HTEqualStrategyNumber];

        /* For hash partitioning, we have just the = strategy. */
        if (eq_clauses != NIL)
        {
          PartClauseInfo *pc;
          List     *pc_steps;
          List     *prefix = NIL;
          int     last_keyno;
          ListCell   *lc1;

          /*
           * Locate the clause for the greatest column.  This may
           * not belong to the last partition key, but it is the
           * clause belonging to the last partition key we found a
           * clause for above.
           */
          pc = llast(eq_clauses);

          /*
           * There might be multiple clauses which matched to that
           * partition key; find the first such clause.  While at
           * it, add all the clauses before that one to 'prefix'.
           */
          last_keyno = pc->keyno;
          foreach(lc, eq_clauses)
          {
            pc = lfirst(lc);
            if (pc->keyno == last_keyno)
              break;
            prefix = lappend(prefix, pc);
          }

          /*
           * For each clause for the "last" column, after appending
           * the clause's own expression to the 'prefix', we'll
           * generate one step using the so generated vector and
           * assign = as its strategy.  Actually, 'prefix' might
           * contain multiple clauses for the same key, in which
           * case, we must generate steps for various combinations
           * of expressions of different keys, which
           * get_steps_using_prefix will take care of for us.
           */
          for_each_cell(lc1, eq_clauses, lc)
          {
            pc = lfirst(lc1);

            /*
             * Note that we pass nullkeys for step_nullkeys,
             * because we need to tell hash partition bound search
             * function which of the keys we found IS NULL clauses
             * for.
             */
            Assert(pc->op_strategy == HTEqualStrategyNumber);
            pc_steps =
              get_steps_using_prefix(context,
                           HTEqualStrategyNumber,
                           false,
                           pc->expr,
                           pc->cmpfn,
                           nullkeys,
                           prefix);
            opsteps = list_concat(opsteps, pc_steps);
          }
        }
        break;
      }

    default:
      elog(ERROR, "invalid partition strategy: %c",
         part_scheme->strategy);
      break;
  }

  return opsteps;
}

/*
 * If the partition key has a collation, then the clause must have the same
 * input collation.  If the partition key is non-collatable, we assume the
 * collation doesn't matter, because while collation wasn't considered when
 * performing partitioning, the clause still may have a collation assigned
 * due to the other input being of a collatable type.
 *
 * See also IndexCollMatchesExprColl.
 */
#define PartCollMatchesExprColl(partcoll, exprcoll) \
  ((partcoll) == InvalidOid || (partcoll) == (exprcoll))

/*
 * match_clause_to_partition_key
 *    Attempt to match the given 'clause' with the specified partition key.
 *
 * Return value is:
 * * PARTCLAUSE_NOMATCH if the clause doesn't match this partition key (but
 *   caller should keep trying, because it might match a subsequent key).
 *   Output arguments: none set.
 *
 * * PARTCLAUSE_MATCH_CLAUSE if there is a match.
 *   Output arguments: *pc is set to a PartClauseInfo constructed for the
 *   matched clause.
 *
 * * PARTCLAUSE_MATCH_NULLNESS if there is a match, and the matched clause was
 *   either a "a IS NULL" or "a IS NOT NULL" clause.
 *   Output arguments: *clause_is_not_null is set to false in the former case
 *   true otherwise.
 *
 * * PARTCLAUSE_MATCH_STEPS if there is a match.
 *   Output arguments: *clause_steps is set to the list of recursively
 *   generated steps for the clause.
 *
 * * PARTCLAUSE_MATCH_CONTRADICT if the clause is self-contradictory, ie
 *   it provably returns FALSE or NULL.
 *   Output arguments: none set.
 *
 * * PARTCLAUSE_UNSUPPORTED if the clause doesn't match this partition key
 *   and couldn't possibly match any other one either, due to its form or
 *   properties (such as containing a volatile function).
 *   Output arguments: none set.
 */
static PartClauseMatchStatus
match_clause_to_partition_key(GeneratePruningStepsContext *context,
                Expr *clause, Expr *partkey, int partkeyidx,
                bool *clause_is_not_null, PartClauseInfo **pc,
                List **clause_steps)
{
  PartClauseMatchStatus boolmatchstatus;
  PartitionScheme part_scheme = context->rel->part_scheme;
  Oid     partopfamily = part_scheme->partopfamily[partkeyidx],
        partcoll = part_scheme->partcollation[partkeyidx];
  Expr     *expr;
  bool    notclause;

  /*
   * Recognize specially shaped clauses that match a Boolean partition key.
   */
  boolmatchstatus = match_boolean_partition_clause(partopfamily, clause,
                           partkey, &expr,
                           &notclause);

  if (boolmatchstatus == PARTCLAUSE_MATCH_CLAUSE)
  {
    PartClauseInfo *partclause;

    /*
     * For bool tests in the form of partkey IS NOT true and IS NOT false,
     * we invert these clauses.  Effectively, "partkey IS NOT true"
     * becomes "partkey IS false OR partkey IS NULL".  We do this by
     * building an OR BoolExpr and forming a clause just like that and
     * punt it off to gen_partprune_steps_internal() to generate pruning
     * steps.
     */
    if (notclause)
    {
      List     *new_clauses;
      List     *or_clause;
      BooleanTest *new_booltest = (BooleanTest *) copyObject(clause);
      NullTest   *nulltest;

      /* We expect 'notclause' to only be set to true for BooleanTests */
      Assert(IsA(clause, BooleanTest));

      /* reverse the bool test */
      if (new_booltest->booltesttype == IS_NOT_TRUE)
        new_booltest->booltesttype = IS_FALSE;
      else if (new_booltest->booltesttype == IS_NOT_FALSE)
        new_booltest->booltesttype = IS_TRUE;
      else
      {
        /*
         * We only expect match_boolean_partition_clause to return
         * PARTCLAUSE_MATCH_CLAUSE for IS_NOT_TRUE and IS_NOT_FALSE.
         */
        Assert(false);
      }

      nulltest = makeNode(NullTest);
      nulltest->arg = copyObject(partkey);
      nulltest->nulltesttype = IS_NULL;
      nulltest->argisrow = false;
      nulltest->location = -1;

      new_clauses = list_make2(new_booltest, nulltest);
      or_clause = list_make1(makeBoolExpr(OR_EXPR, new_clauses, -1));

      /* Finally, generate steps */
      *clause_steps = gen_partprune_steps_internal(context, or_clause);

      if (context->contradictory)
        return PARTCLAUSE_MATCH_CONTRADICT; /* shouldn't happen */
      else if (*clause_steps == NIL)
        return PARTCLAUSE_UNSUPPORTED; /* step generation failed */
      return PARTCLAUSE_MATCH_STEPS;
    }

    partclause = (PartClauseInfo *) palloc(sizeof(PartClauseInfo));
    partclause->keyno = partkeyidx;
    /* Do pruning with the Boolean equality operator. */
    partclause->opno = BooleanEqualOperator;
    partclause->op_is_ne = false;
    partclause->expr = expr;
    /* We know that expr is of Boolean type. */
    partclause->cmpfn = part_scheme->partsupfunc[partkeyidx].fn_oid;
    partclause->op_strategy = InvalidStrategy;

    *pc = partclause;

    return PARTCLAUSE_MATCH_CLAUSE;
  }
  else if (boolmatchstatus == PARTCLAUSE_MATCH_NULLNESS)
  {
    /*
     * Handle IS UNKNOWN and IS NOT UNKNOWN.  These just logically
     * translate to IS NULL and IS NOT NULL.
     */
    *clause_is_not_null = notclause;
    return PARTCLAUSE_MATCH_NULLNESS;
  }
  else if (IsA(clause, OpExpr) &&
       list_length(((OpExpr *) clause)->args) == 2)
  {
    OpExpr     *opclause = (OpExpr *) clause;
    Expr     *leftop,
           *rightop;
    Oid     opno,
          op_lefttype,
          op_righttype,
          negator = InvalidOid;
    Oid     cmpfn;
    int     op_strategy;
    bool    is_opne_listp = false;
    PartClauseInfo *partclause;

    leftop = (Expr *) get_leftop(clause);
    if (IsA(leftop, RelabelType))
      leftop = ((RelabelType *) leftop)->arg;
    rightop = (Expr *) get_rightop(clause);
    if (IsA(rightop, RelabelType))
      rightop = ((RelabelType *) rightop)->arg;
    opno = opclause->opno;

    /* check if the clause matches this partition key */
    if (equal(leftop, partkey))
      expr = rightop;
    else if (equal(rightop, partkey))
    {
      /*
       * It's only useful if we can commute the operator to put the
       * partkey on the left.  If we can't, the clause can be deemed
       * UNSUPPORTED.  Even if its leftop matches some later partkey, we
       * now know it has Vars on the right, so it's no use.
       */
      opno = get_commutator(opno);
      if (!OidIsValid(opno))
        return PARTCLAUSE_UNSUPPORTED;
      expr = leftop;
    }
    else
      /* clause does not match this partition key, but perhaps next. */
      return PARTCLAUSE_NOMATCH;

    /*
     * Partition key match also requires collation match.  There may be
     * multiple partkeys with the same expression but different
     * collations, so failure is NOMATCH.
     */
    if (!PartCollMatchesExprColl(partcoll, opclause->inputcollid))
      return PARTCLAUSE_NOMATCH;

    /*
     * See if the operator is relevant to the partitioning opfamily.
     *
     * Normally we only care about operators that are listed as being part
     * of the partitioning operator family.  But there is one exception:
     * the not-equals operators are not listed in any operator family
     * whatsoever, but their negators (equality) are.  We can use one of
     * those if we find it, but only for list partitioning.
     *
     * Note: we report NOMATCH on failure if the negator isn't the
     * equality operator for the partkey's opfamily as other partkeys may
     * have the same expression but different opfamily.  That's unlikely,
     * but not much more so than duplicate expressions with different
     * collations.
     */
    if (op_in_opfamily(opno, partopfamily))
    {
      get_op_opfamily_properties(opno, partopfamily, false,
                     &op_strategy, &op_lefttype,
                     &op_righttype);
    }
    else
    {
      /* not supported for anything apart from LIST partitioned tables */
      if (part_scheme->strategy != PARTITION_STRATEGY_LIST)
        return PARTCLAUSE_UNSUPPORTED;

      /* See if the negator is equality */
      negator = get_negator(opno);
      if (OidIsValid(negator) && op_in_opfamily(negator, partopfamily))
      {
        get_op_opfamily_properties(negator, partopfamily, false,
                       &op_strategy, &op_lefttype,
                       &op_righttype);
        if (op_strategy == BTEqualStrategyNumber)
          is_opne_listp = true; /* bingo */
      }

      /* Nope, it's not <> either. */
      if (!is_opne_listp)
        return PARTCLAUSE_NOMATCH;
    }

    /*
     * Only allow strict operators.  This will guarantee nulls are
     * filtered.  (This test is likely useless, since btree and hash
     * comparison operators are generally strict.)
     */
    if (!op_strict(opno))
      return PARTCLAUSE_UNSUPPORTED;

    /*
     * OK, we have a match to the partition key and a suitable operator.
     * Examine the other argument to see if it's usable for pruning.
     *
     * In most of these cases, we can return UNSUPPORTED because the same
     * failure would occur no matter which partkey it's matched to.  (In
     * particular, now that we've successfully matched one side of the
     * opclause to a partkey, there is no chance that matching the other
     * side to another partkey will produce a usable result, since that'd
     * mean there are Vars on both sides.)
     *
     * Also, if we reject an argument for a target-dependent reason, set
     * appropriate fields of *context to report that.  We postpone these
     * tests until after matching the partkey and the operator, so as to
     * reduce the odds of setting the context fields for clauses that do
     * not end up contributing to pruning steps.
     *
     * First, check for non-Const argument.  (We assume that any immutable
     * subexpression will have been folded to a Const already.)
     */
    if (!IsA(expr, Const))
    {
      Bitmapset  *paramids;

      /*
       * When pruning in the planner, we only support pruning using
       * comparisons to constants.  We cannot prune on the basis of
       * anything that's not immutable.  (Note that has_mutable_arg and
       * has_exec_param do not get set for this target value.)
       */
      if (context->target == PARTTARGET_PLANNER)
        return PARTCLAUSE_UNSUPPORTED;

      /*
       * We can never prune using an expression that contains Vars.
       */
      if (contain_var_clause((Node *) expr))
        return PARTCLAUSE_UNSUPPORTED;

      /*
       * And we must reject anything containing a volatile function.
       * Stable functions are OK though.
       */
      if (contain_volatile_functions((Node *) expr))
        return PARTCLAUSE_UNSUPPORTED;

      /*
       * See if there are any exec Params.  If so, we can only use this
       * expression during per-scan pruning.
       */
      paramids = pull_exec_paramids(expr);
      if (!bms_is_empty(paramids))
      {
        context->has_exec_param = true;
        if (context->target != PARTTARGET_EXEC)
          return PARTCLAUSE_UNSUPPORTED;
      }
      else
      {
        /* It's potentially usable, but mutable */
        context->has_mutable_arg = true;
      }
    }

    /*
     * Check whether the comparison operator itself is immutable.  (We
     * assume anything that's in a btree or hash opclass is at least
     * stable, but we need to check for immutability.)
     */
    if (op_volatile(opno) != PROVOLATILE_IMMUTABLE)
    {
      context->has_mutable_op = true;

      /*
       * When pruning in the planner, we cannot prune with mutable
       * operators.
       */
      if (context->target == PARTTARGET_PLANNER)
        return PARTCLAUSE_UNSUPPORTED;
    }

    /*
     * Now find the procedure to use, based on the types.  If the clause's
     * other argument is of the same type as the partitioning opclass's
     * declared input type, we can use the procedure cached in
     * PartitionKey.  If not, search for a cross-type one in the same
     * opfamily; if one doesn't exist, report no match.
     */
    if (op_righttype == part_scheme->partopcintype[partkeyidx])
      cmpfn = part_scheme->partsupfunc[partkeyidx].fn_oid;
    else
    {
      switch (part_scheme->strategy)
      {
          /*
           * For range and list partitioning, we need the ordering
           * procedure with lefttype being the partition key's type,
           * and righttype the clause's operator's right type.
           */
        case PARTITION_STRATEGY_LIST:
        case PARTITION_STRATEGY_RANGE:
          cmpfn =
            get_opfamily_proc(part_scheme->partopfamily[partkeyidx],
                      part_scheme->partopcintype[partkeyidx],
                      op_righttype, BTORDER_PROC);
          break;

          /*
           * For hash partitioning, we need the hashing procedure
           * for the clause's type.
           */
        case PARTITION_STRATEGY_HASH:
          cmpfn =
            get_opfamily_proc(part_scheme->partopfamily[partkeyidx],
                      op_righttype, op_righttype,
                      HASHEXTENDED_PROC);
          break;

        default:
          elog(ERROR, "invalid partition strategy: %c",
             part_scheme->strategy);
          cmpfn = InvalidOid; /* keep compiler quiet */
          break;
      }

      if (!OidIsValid(cmpfn))
        return PARTCLAUSE_NOMATCH;
    }

    /*
     * Build the clause, passing the negator if applicable.
     */
    partclause = (PartClauseInfo *) palloc(sizeof(PartClauseInfo));
    partclause->keyno = partkeyidx;
    if (is_opne_listp)
    {
      Assert(OidIsValid(negator));
      partclause->opno = negator;
      partclause->op_is_ne = true;
      partclause->op_strategy = InvalidStrategy;
    }
    else
    {
      partclause->opno = opno;
      partclause->op_is_ne = false;
      partclause->op_strategy = op_strategy;
    }
    partclause->expr = expr;
    partclause->cmpfn = cmpfn;

    *pc = partclause;

    return PARTCLAUSE_MATCH_CLAUSE;
  }
  else if (IsA(clause, ScalarArrayOpExpr))
  {
    ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) clause;
    Oid     saop_op = saop->opno;
    Oid     saop_coll = saop->inputcollid;
    Expr     *leftop = (Expr *) linitial(saop->args),
           *rightop = (Expr *) lsecond(saop->args);
    List     *elem_exprs,
           *elem_clauses;
    ListCell   *lc1;

    if (IsA(leftop, RelabelType))
      leftop = ((RelabelType *) leftop)->arg;

    /* check if the LHS matches this partition key */
    if (!equal(leftop, partkey) ||
      !PartCollMatchesExprColl(partcoll, saop->inputcollid))
      return PARTCLAUSE_NOMATCH;

    /*
     * See if the operator is relevant to the partitioning opfamily.
     *
     * In case of NOT IN (..), we get a '<>', which we handle if list
     * partitioning is in use and we're able to confirm that it's negator
     * is a btree equality operator belonging to the partitioning operator
     * family.  As above, report NOMATCH for non-matching operator.
     */
    if (!op_in_opfamily(saop_op, partopfamily))
    {
      Oid     negator;

      if (part_scheme->strategy != PARTITION_STRATEGY_LIST)
        return PARTCLAUSE_NOMATCH;

      negator = get_negator(saop_op);
      if (OidIsValid(negator) && op_in_opfamily(negator, partopfamily))
      {
        int     strategy;
        Oid     lefttype,
              righttype;

        get_op_opfamily_properties(negator, partopfamily,
                       false, &strategy,
                       &lefttype, &righttype);
        if (strategy != BTEqualStrategyNumber)
          return PARTCLAUSE_NOMATCH;
      }
      else
        return PARTCLAUSE_NOMATCH; /* no useful negator */
    }

    /*
     * Only allow strict operators.  This will guarantee nulls are
     * filtered.  (This test is likely useless, since btree and hash
     * comparison operators are generally strict.)
     */
    if (!op_strict(saop_op))
      return PARTCLAUSE_UNSUPPORTED;

    /*
     * OK, we have a match to the partition key and a suitable operator.
     * Examine the array argument to see if it's usable for pruning.  This
     * is identical to the logic for a plain OpExpr.
     */
    if (!IsA(rightop, Const))
    {
      Bitmapset  *paramids;

      /*
       * When pruning in the planner, we only support pruning using
       * comparisons to constants.  We cannot prune on the basis of
       * anything that's not immutable.  (Note that has_mutable_arg and
       * has_exec_param do not get set for this target value.)
       */
      if (context->target == PARTTARGET_PLANNER)
        return PARTCLAUSE_UNSUPPORTED;

      /*
       * We can never prune using an expression that contains Vars.
       */
      if (contain_var_clause((Node *) rightop))
        return PARTCLAUSE_UNSUPPORTED;

      /*
       * And we must reject anything containing a volatile function.
       * Stable functions are OK though.
       */
      if (contain_volatile_functions((Node *) rightop))
        return PARTCLAUSE_UNSUPPORTED;

      /*
       * See if there are any exec Params.  If so, we can only use this
       * expression during per-scan pruning.
       */
      paramids = pull_exec_paramids(rightop);
      if (!bms_is_empty(paramids))
      {
        context->has_exec_param = true;
        if (context->target != PARTTARGET_EXEC)
          return PARTCLAUSE_UNSUPPORTED;
      }
      else
      {
        /* It's potentially usable, but mutable */
        context->has_mutable_arg = true;
      }
    }

    /*
     * Check whether the comparison operator itself is immutable.  (We
     * assume anything that's in a btree or hash opclass is at least
     * stable, but we need to check for immutability.)
     */
    if (op_volatile(saop_op) != PROVOLATILE_IMMUTABLE)
    {
      context->has_mutable_op = true;

      /*
       * When pruning in the planner, we cannot prune with mutable
       * operators.
       */
      if (context->target == PARTTARGET_PLANNER)
        return PARTCLAUSE_UNSUPPORTED;
    }

    /*
     * Examine the contents of the array argument.
     */
    elem_exprs = NIL;
    if (IsA(rightop, Const))
    {
      /*
       * For a constant array, convert the elements to a list of Const
       * nodes, one for each array element (excepting nulls).
       */
      Const    *arr = (Const *) rightop;
      ArrayType  *arrval;
      int16   elemlen;
      bool    elembyval;
      char    elemalign;
      Datum    *elem_values;
      bool     *elem_nulls;
      int     num_elems,
            i;

      /* If the array itself is null, the saop returns null */
      if (arr->constisnull)
        return PARTCLAUSE_MATCH_CONTRADICT;

      arrval = DatumGetArrayTypeP(arr->constvalue);
      get_typlenbyvalalign(ARR_ELEMTYPE(arrval),
                 &elemlen, &elembyval, &elemalign);
      deconstruct_array(arrval,
                ARR_ELEMTYPE(arrval),
                elemlen, elembyval, elemalign,
                &elem_values, &elem_nulls,
                &num_elems);
      for (i = 0; i < num_elems; i++)
      {
        Const    *elem_expr;

        /*
         * A null array element must lead to a null comparison result,
         * since saop_op is known strict.  We can ignore it in the
         * useOr case, but otherwise it implies self-contradiction.
         */
        if (elem_nulls[i])
        {
          if (saop->useOr)
            continue;
          return PARTCLAUSE_MATCH_CONTRADICT;
        }

        elem_expr = makeConst(ARR_ELEMTYPE(arrval), -1,
                    arr->constcollid, elemlen,
                    elem_values[i], false, elembyval);
        elem_exprs = lappend(elem_exprs, elem_expr);
      }
    }
    else if (IsA(rightop, ArrayExpr))
    {
      ArrayExpr  *arrexpr = castNode(ArrayExpr, rightop);

      /*
       * For a nested ArrayExpr, we don't know how to get the actual
       * scalar values out into a flat list, so we give up doing
       * anything with this ScalarArrayOpExpr.
       */
      if (arrexpr->multidims)
        return PARTCLAUSE_UNSUPPORTED;

      /*
       * Otherwise, we can just use the list of element values.
       */
      elem_exprs = arrexpr->elements;
    }
    else
    {
      /* Give up on any other clause types. */
      return PARTCLAUSE_UNSUPPORTED;
    }

    /*
     * Now generate a list of clauses, one for each array element, of the
     * form leftop saop_op elem_expr
     */
    elem_clauses = NIL;
    foreach(lc1, elem_exprs)
    {
      Expr     *elem_clause;

      elem_clause = make_opclause(saop_op, BOOLOID, false,
                    leftop, lfirst(lc1),
                    InvalidOid, saop_coll);
      elem_clauses = lappend(elem_clauses, elem_clause);
    }

    /*
     * If we have an ANY clause and multiple elements, now turn the list
     * of clauses into an OR expression.
     */
    if (saop->useOr && list_length(elem_clauses) > 1)
      elem_clauses = list_make1(makeBoolExpr(OR_EXPR, elem_clauses, -1));

    /* Finally, generate steps */
    *clause_steps = gen_partprune_steps_internal(context, elem_clauses);
    if (context->contradictory)
      return PARTCLAUSE_MATCH_CONTRADICT;
    else if (*clause_steps == NIL)
      return PARTCLAUSE_UNSUPPORTED; /* step generation failed */
    return PARTCLAUSE_MATCH_STEPS;
  }
  else if (IsA(clause, NullTest))
  {
    NullTest   *nulltest = (NullTest *) clause;
    Expr     *arg = nulltest->arg;

    if (IsA(arg, RelabelType))
      arg = ((RelabelType *) arg)->arg;

    /* Does arg match with this partition key column? */
    if (!equal(arg, partkey))
      return PARTCLAUSE_NOMATCH;

    *clause_is_not_null = (nulltest->nulltesttype == IS_NOT_NULL);

    return PARTCLAUSE_MATCH_NULLNESS;
  }

  /*
   * If we get here then the return value depends on the result of the
   * match_boolean_partition_clause call above.  If the call returned
   * PARTCLAUSE_UNSUPPORTED then we're either not dealing with a bool qual
   * or the bool qual is not suitable for pruning.  Since the qual didn't
   * match up to any of the other qual types supported here, then trying to
   * match it against any other partition key is a waste of time, so just
   * return PARTCLAUSE_UNSUPPORTED.  If the qual just couldn't be matched to
   * this partition key, then it may match another, so return
   * PARTCLAUSE_NOMATCH.  The only other value that
   * match_boolean_partition_clause can return is PARTCLAUSE_MATCH_CLAUSE,
   * and since that value was already dealt with above, then we can just
   * return boolmatchstatus.
   */
  return boolmatchstatus;
}

/*
 * get_steps_using_prefix
 *    Generate a list of PartitionPruneStepOps based on the given input.
 *
 * 'step_lastexpr' and 'step_lastcmpfn' are the Expr and comparison function
 * belonging to the final partition key that we have a clause for.  'prefix'
 * is a list of PartClauseInfos for partition key numbers prior to the given
 * 'step_lastexpr' and 'step_lastcmpfn'.  'prefix' may contain multiple
 * PartClauseInfos belonging to a single partition key.  We will generate a
 * PartitionPruneStepOp for each combination of the given PartClauseInfos
 * using, at most, one PartClauseInfo per partition key.
 *
 * For LIST and RANGE partitioned tables, callers must ensure that
 * step_nullkeys is NULL, and that prefix contains at least one clause for
 * each of the partition keys prior to the key that 'step_lastexpr' and
 * 'step_lastcmpfn' belong to.
 *
 * For HASH partitioned tables, callers must ensure that 'prefix' contains at
 * least one clause for each of the partition keys apart from the final key
 * (the expr and comparison function for the final key are in 'step_lastexpr'
 * and 'step_lastcmpfn').  A bit set in step_nullkeys can substitute clauses
 * in the 'prefix' list for any given key.  If a bit is set in 'step_nullkeys'
 * for a given key, then there must be no PartClauseInfo for that key in the
 * 'prefix' list.
 *
 * For each of the above cases, callers must ensure that PartClauseInfos in
 * 'prefix' are sorted in ascending order of keyno.
 */
static List *
get_steps_using_prefix(GeneratePruningStepsContext *context,
             StrategyNumber step_opstrategy,
             bool step_op_is_ne,
             Expr *step_lastexpr,
             Oid step_lastcmpfn,
             Bitmapset *step_nullkeys,
             List *prefix)
{
  /* step_nullkeys must be empty for RANGE and LIST partitioned tables */
  Assert(step_nullkeys == NULL ||
       context->rel->part_scheme->strategy == PARTITION_STRATEGY_HASH);

  /*
   * No recursive processing is required when 'prefix' is an empty list.
   * This occurs when there is only 1 partition key column.
   */
  if (prefix == NIL)
  {
    PartitionPruneStep *step;

    step = gen_prune_step_op(context,
                 step_opstrategy,
                 step_op_is_ne,
                 list_make1(step_lastexpr),
                 list_make1_oid(step_lastcmpfn),
                 step_nullkeys);
    return list_make1(step);
  }

  /* Recurse to generate steps for every combination of clauses. */
  return get_steps_using_prefix_recurse(context,
                      step_opstrategy,
                      step_op_is_ne,
                      step_lastexpr,
                      step_lastcmpfn,
                      step_nullkeys,
                      prefix,
                      list_head(prefix),
                      NIL, NIL);
}

/*
 * get_steps_using_prefix_recurse
 *    Generate and return a list of PartitionPruneStepOps using the 'prefix'
 *    list of PartClauseInfos starting at the 'start' cell.
 *
 * When 'prefix' contains multiple PartClauseInfos for a single partition key
 * we create a PartitionPruneStepOp for each combination of duplicated
 * PartClauseInfos.  The returned list will contain a PartitionPruneStepOp
 * for each unique combination of input PartClauseInfos containing at most one
 * PartClauseInfo per partition key.
 *
 * 'prefix' is the input list of PartClauseInfos sorted by keyno.
 * 'start' marks the cell that searching the 'prefix' list should start from.
 * 'step_exprs' and 'step_cmpfns' each contains the expressions and cmpfns
 * we've generated so far from the clauses for the previous part keys.
 */
static List *
get_steps_using_prefix_recurse(GeneratePruningStepsContext *context,
                 StrategyNumber step_opstrategy,
                 bool step_op_is_ne,
                 Expr *step_lastexpr,
                 Oid step_lastcmpfn,
                 Bitmapset *step_nullkeys,
                 List *prefix,
                 ListCell *start,
                 List *step_exprs,
                 List *step_cmpfns)
{
  List     *result = NIL;
  ListCell   *lc;
  int     cur_keyno;
  int     final_keyno;

  /* Actually, recursion would be limited by PARTITION_MAX_KEYS. */
  check_stack_depth();

  Assert(start != NULL);
  cur_keyno = ((PartClauseInfo *) lfirst(start))->keyno;
  final_keyno = ((PartClauseInfo *) llast(prefix))->keyno;

  /* Check if we need to recurse. */
  if (cur_keyno < final_keyno)
  {
    PartClauseInfo *pc;
    ListCell   *next_start;

    /*
     * Find the first PartClauseInfo belonging to the next partition key,
     * the next recursive call must start iteration of the prefix list
     * from that point.
     */
    for_each_cell(lc, prefix, start)
    {
      pc = lfirst(lc);

      if (pc->keyno > cur_keyno)
        break;
    }

    /* record where to start iterating in the next recursive call */
    next_start = lc;

    /*
     * For each PartClauseInfo with keyno set to cur_keyno, add its expr
     * and cmpfn to step_exprs and step_cmpfns, respectively, and recurse
     * using 'next_start' as the starting point in the 'prefix' list.
     */
    for_each_cell(lc, prefix, start)
    {
      List     *moresteps;
      List     *step_exprs1,
             *step_cmpfns1;

      pc = lfirst(lc);
      if (pc->keyno == cur_keyno)
      {
        /* Leave the original step_exprs unmodified. */
        step_exprs1 = list_copy(step_exprs);
        step_exprs1 = lappend(step_exprs1, pc->expr);

        /* Leave the original step_cmpfns unmodified. */
        step_cmpfns1 = list_copy(step_cmpfns);
        step_cmpfns1 = lappend_oid(step_cmpfns1, pc->cmpfn);
      }
      else
      {
        /* check the 'prefix' list is sorted correctly */
        Assert(pc->keyno > cur_keyno);
        break;
      }

      moresteps = get_steps_using_prefix_recurse(context,
                             step_opstrategy,
                             step_op_is_ne,
                             step_lastexpr,
                             step_lastcmpfn,
                             step_nullkeys,
                             prefix,
                             next_start,
                             step_exprs1,
                             step_cmpfns1);
      result = list_concat(result, moresteps);

      list_free(step_exprs1);
      list_free(step_cmpfns1);
    }
  }
  else
  {
    /*
     * End the current recursion cycle and start generating steps, one for
     * each clause with cur_keyno, which is all clauses from here onward
     * till the end of the list.  Note that for hash partitioning,
     * step_nullkeys is allowed to be non-empty, in which case step_exprs
     * would only contain expressions for the partition keys that are not
     * specified in step_nullkeys.
     */
    Assert(list_length(step_exprs) == cur_keyno ||
         !bms_is_empty(step_nullkeys));

    /*
     * Note also that for hash partitioning, each partition key should
     * have either equality clauses or an IS NULL clause, so if a
     * partition key doesn't have an expression, it would be specified in
     * step_nullkeys.
     */
    Assert(context->rel->part_scheme->strategy
         != PARTITION_STRATEGY_HASH ||
         list_length(step_exprs) + 2 + bms_num_members(step_nullkeys) ==
         context->rel->part_scheme->partnatts);
    for_each_cell(lc, prefix, start)
    {
      PartClauseInfo *pc = lfirst(lc);
      PartitionPruneStep *step;
      List     *step_exprs1,
             *step_cmpfns1;

      Assert(pc->keyno == cur_keyno);

      /* Leave the original step_exprs unmodified. */
      step_exprs1 = list_copy(step_exprs);
      step_exprs1 = lappend(step_exprs1, pc->expr);
      step_exprs1 = lappend(step_exprs1, step_lastexpr);

      /* Leave the original step_cmpfns unmodified. */
      step_cmpfns1 = list_copy(step_cmpfns);
      step_cmpfns1 = lappend_oid(step_cmpfns1, pc->cmpfn);
      step_cmpfns1 = lappend_oid(step_cmpfns1, step_lastcmpfn);

      step = gen_prune_step_op(context,
                   step_opstrategy, step_op_is_ne,
                   step_exprs1, step_cmpfns1,
                   step_nullkeys);
      result = lappend(result, step);
    }
  }

  return result;
}

/*
 * get_matching_hash_bounds
 *    Determine offset of the hash bound matching the specified values,
 *    considering that all the non-null values come from clauses containing
 *    a compatible hash equality operator and any keys that are null come
 *    from an IS NULL clause.
 *
 * Generally this function will return a single matching bound offset,
 * although if a partition has not been setup for a given modulus then we may
 * return no matches.  If the number of clauses found don't cover the entire
 * partition key, then we'll need to return all offsets.
 *
 * 'opstrategy' if non-zero must be HTEqualStrategyNumber.
 *
 * 'values' contains Datums indexed by the partition key to use for pruning.
 *
 * 'nvalues', the number of Datums in the 'values' array.
 *
 * 'partsupfunc' contains partition hashing functions that can produce correct
 * hash for the type of the values contained in 'values'.
 *
 * 'nullkeys' is the set of partition keys that are null.
 */
static PruneStepResult *
get_matching_hash_bounds(PartitionPruneContext *context,
             StrategyNumber opstrategy, Datum *values, int nvalues,
             FmgrInfo *partsupfunc, Bitmapset *nullkeys)
{
  PruneStepResult *result = (PruneStepResult *) palloc0(sizeof(PruneStepResult));
  PartitionBoundInfo boundinfo = context->boundinfo;
  int      *partindices = boundinfo->indexes;
  int     partnatts = context->partnatts;
  bool    isnull[PARTITION_MAX_KEYS];
  int     i;
  uint64    rowHash;
  int     greatest_modulus;
  Oid      *partcollation = context->partcollation;

  Assert(context->strategy == PARTITION_STRATEGY_HASH);

  /*
   * For hash partitioning we can only perform pruning based on equality
   * clauses to the partition key or IS NULL clauses.  We also can only
   * prune if we got values for all keys.
   */
  if (nvalues + bms_num_members(nullkeys) == partnatts)
  {
    /*
     * If there are any values, they must have come from clauses
     * containing an equality operator compatible with hash partitioning.
     */
    Assert(opstrategy == HTEqualStrategyNumber || nvalues == 0);

    for (i = 0; i < partnatts; i++)
      isnull[i] = bms_is_member(i, nullkeys);

    rowHash = compute_partition_hash_value(partnatts, partsupfunc, partcollation,
                         values, isnull);

    greatest_modulus = boundinfo->nindexes;
    if (partindices[rowHash % greatest_modulus] >= 0)
      result->bound_offsets =
        bms_make_singleton(rowHash % greatest_modulus);
  }
  else
  {
    /* Report all valid offsets into the boundinfo->indexes array. */
    result->bound_offsets = bms_add_range(NULL, 0,
                        boundinfo->nindexes - 1);
  }

  /*
   * There is neither a special hash null partition or the default hash
   * partition.
   */
  result->scan_null = result->scan_default = false;

  return result;
}

/*
 * get_matching_list_bounds
 *    Determine the offsets of list bounds matching the specified value,
 *    according to the semantics of the given operator strategy
 *
 * scan_default will be set in the returned struct, if the default partition
 * needs to be scanned, provided one exists at all.  scan_null will be set if
 * the special null-accepting partition needs to be scanned.
 *
 * 'opstrategy' if non-zero must be a btree strategy number.
 *
 * 'value' contains the value to use for pruning.
 *
 * 'nvalues', if non-zero, should be exactly 1, because of list partitioning.
 *
 * 'partsupfunc' contains the list partitioning comparison function to be used
 * to perform partition_list_bsearch
 *
 * 'nullkeys' is the set of partition keys that are null.
 */
static PruneStepResult *
get_matching_list_bounds(PartitionPruneContext *context,
             StrategyNumber opstrategy, Datum value, int nvalues,
             FmgrInfo *partsupfunc, Bitmapset *nullkeys)
{
  PruneStepResult *result = (PruneStepResult *) palloc0(sizeof(PruneStepResult));
  PartitionBoundInfo boundinfo = context->boundinfo;
  int     off,
        minoff,
        maxoff;
  bool    is_equal;
  bool    inclusive = false;
  Oid      *partcollation = context->partcollation;

  Assert(context->strategy == PARTITION_STRATEGY_LIST);
  Assert(context->partnatts == 1);

  result->scan_null = result->scan_default = false;

  if (!bms_is_empty(nullkeys))
  {
    /*
     * Nulls may exist in only one partition - the partition whose
     * accepted set of values includes null or the default partition if
     * the former doesn't exist.
     */
    if (partition_bound_accepts_nulls(boundinfo))
      result->scan_null = true;
    else
      result->scan_default = partition_bound_has_default(boundinfo);
    return result;
  }

  /*
   * If there are no datums to compare keys with, but there are partitions,
   * just return the default partition if one exists.
   */
  if (boundinfo->ndatums == 0)
  {
    result->scan_default = partition_bound_has_default(boundinfo);
    return result;
  }

  minoff = 0;
  maxoff = boundinfo->ndatums - 1;

  /*
   * If there are no values to compare with the datums in boundinfo, it
   * means the caller asked for partitions for all non-null datums.  Add
   * indexes of *all* partitions, including the default if any.
   */
  if (nvalues == 0)
  {
    Assert(boundinfo->ndatums > 0);
    result->bound_offsets = bms_add_range(NULL, 0,
                        boundinfo->ndatums - 1);
    result->scan_default = partition_bound_has_default(boundinfo);
    return result;
  }

  /* Special case handling of values coming from a <> operator clause. */
  if (opstrategy == InvalidStrategy)
  {
    /*
     * First match to all bounds.  We'll remove any matching datums below.
     */
    Assert(boundinfo->ndatums > 0);
    result->bound_offsets = bms_add_range(NULL, 0,
                        boundinfo->ndatums - 1);

    off = partition_list_bsearch(partsupfunc, partcollation, boundinfo,
                   value, &is_equal);
    if (off >= 0 && is_equal)
    {

      /* We have a match. Remove from the result. */
      Assert(boundinfo->indexes[off] >= 0);
      result->bound_offsets = bms_del_member(result->bound_offsets,
                           off);
    }

    /* Always include the default partition if any. */
    result->scan_default = partition_bound_has_default(boundinfo);

    return result;
  }

  /*
   * With range queries, always include the default list partition, because
   * list partitions divide the key space in a discontinuous manner, not all
   * values in the given range will have a partition assigned.  This may not
   * technically be true for some data types (e.g. integer types), however,
   * we currently lack any sort of infrastructure to provide us with proofs
   * that would allow us to do anything smarter here.
   */
  if (opstrategy != BTEqualStrategyNumber)
    result->scan_default = partition_bound_has_default(boundinfo);

  switch (opstrategy)
  {
    case BTEqualStrategyNumber:
      off = partition_list_bsearch(partsupfunc,
                     partcollation,
                     boundinfo, value,
                     &is_equal);
      if (off >= 0 && is_equal)
      {
        Assert(boundinfo->indexes[off] >= 0);
        result->bound_offsets = bms_make_singleton(off);
      }
      else
        result->scan_default = partition_bound_has_default(boundinfo);
      return result;

    case BTGreaterEqualStrategyNumber:
      inclusive = true;
      /* fall through */
    case BTGreaterStrategyNumber:
      off = partition_list_bsearch(partsupfunc,
                     partcollation,
                     boundinfo, value,
                     &is_equal);
      if (off >= 0)
      {
        /* We don't want the matched datum to be in the result. */
        if (!is_equal || !inclusive)
          off++;
      }
      else
      {
        /*
         * This case means all partition bounds are greater, which in
         * turn means that all partitions satisfy this key.
         */
        off = 0;
      }

      /*
       * off is greater than the numbers of datums we have partitions
       * for.  The only possible partition that could contain a match is
       * the default partition, but we must've set context->scan_default
       * above anyway if one exists.
       */
      if (off > boundinfo->ndatums - 1)
        return result;

      minoff = off;
      break;

    case BTLessEqualStrategyNumber:
      inclusive = true;
      /* fall through */
    case BTLessStrategyNumber:
      off = partition_list_bsearch(partsupfunc,
                     partcollation,
                     boundinfo, value,
                     &is_equal);
      if (off >= 0 && is_equal && !inclusive)
        off--;

      /*
       * off is smaller than the datums of all non-default partitions.
       * The only possible partition that could contain a match is the
       * default partition, but we must've set context->scan_default
       * above anyway if one exists.
       */
      if (off < 0)
        return result;

      maxoff = off;
      break;

    default:
      elog(ERROR, "invalid strategy number %d", opstrategy);
      break;
  }

  Assert(minoff >= 0 && maxoff >= 0);
  result->bound_offsets = bms_add_range(NULL, minoff, maxoff);
  return result;
}


/*
 * get_matching_range_bounds
 *    Determine the offsets of range bounds matching the specified values,
 *    according to the semantics of the given operator strategy
 *
 * Each datum whose offset is in result is to be treated as the upper bound of
 * the partition that will contain the desired values.
 *
 * scan_default is set in the returned struct if a default partition exists
 * and we're absolutely certain that it needs to be scanned.  We do *not* set
 * it just because values match portions of the key space uncovered by
 * partitions other than default (space which we normally assume to belong to
 * the default partition): the final set of bounds obtained after combining
 * multiple pruning steps might exclude it, so we infer its inclusion
 * elsewhere.
 *
 * 'opstrategy' must be a btree strategy number.
 *
 * 'values' contains Datums indexed by the partition key to use for pruning.
 *
 * 'nvalues', number of Datums in 'values' array. Must be <= context->partnatts.
 *
 * 'partsupfunc' contains the range partitioning comparison functions to be
 * used to perform partition_range_datum_bsearch or partition_rbound_datum_cmp
 * using.
 *
 * 'nullkeys' is the set of partition keys that are null.
 */
static PruneStepResult *
get_matching_range_bounds(PartitionPruneContext *context,
              StrategyNumber opstrategy, Datum *values, int nvalues,
              FmgrInfo *partsupfunc, Bitmapset *nullkeys)
{
  PruneStepResult *result = (PruneStepResult *) palloc0(sizeof(PruneStepResult));
  PartitionBoundInfo boundinfo = context->boundinfo;
  Oid      *partcollation = context->partcollation;
  int     partnatts = context->partnatts;
  int      *partindices = boundinfo->indexes;
  int     off,
        minoff,
        maxoff;
  bool    is_equal;
  bool    inclusive = false;

  Assert(context->strategy == PARTITION_STRATEGY_RANGE);
  Assert(nvalues <= partnatts);

  result->scan_null = result->scan_default = false;

  /*
   * If there are no datums to compare keys with, or if we got an IS NULL
   * clause just return the default partition, if it exists.
   */
  if (boundinfo->ndatums == 0 || !bms_is_empty(nullkeys))
  {
    result->scan_default = partition_bound_has_default(boundinfo);
    return result;
  }

  minoff = 0;
  maxoff = boundinfo->ndatums;

  /*
   * If there are no values to compare with the datums in boundinfo, it
   * means the caller asked for partitions for all non-null datums.  Add
   * indexes of *all* partitions, including the default partition if one
   * exists.
   */
  if (nvalues == 0)
  {
    /* ignore key space not covered by any partitions */
    if (partindices[minoff] < 0)
      minoff++;
    if (partindices[maxoff] < 0)
      maxoff--;

    result->scan_default = partition_bound_has_default(boundinfo);
    Assert(partindices[minoff] >= 0 &&
         partindices[maxoff] >= 0);
    result->bound_offsets = bms_add_range(NULL, minoff, maxoff);

    return result;
  }

  /*
   * If the query does not constrain all key columns, we'll need to scan the
   * default partition, if any.
   */
  if (nvalues < partnatts)
    result->scan_default = partition_bound_has_default(boundinfo);

  switch (opstrategy)
  {
    case BTEqualStrategyNumber:
      /* Look for the smallest bound that is = lookup value. */
      off = partition_range_datum_bsearch(partsupfunc,
                        partcollation,
                        boundinfo,
                        nvalues, values,
                        &is_equal);

      if (off >= 0 && is_equal)
      {
        if (nvalues == partnatts)
        {
          /* There can only be zero or one matching partition. */
          result->bound_offsets = bms_make_singleton(off + 1);
          return result;
        }
        else
        {
          int     saved_off = off;

          /*
           * Since the lookup value contains only a prefix of keys,
           * we must find other bounds that may also match the
           * prefix.  partition_range_datum_bsearch() returns the
           * offset of one of them, find others by checking adjacent
           * bounds.
           */

          /*
           * First find greatest bound that's smaller than the
           * lookup value.
           */
          while (off >= 1)
          {
            int32   cmpval;

            cmpval =
              partition_rbound_datum_cmp(partsupfunc,
                             partcollation,
                             boundinfo->datums[off - 1],
                             boundinfo->kind[off - 1],
                             values, nvalues);
            if (cmpval != 0)
              break;
            off--;
          }

          Assert(0 ==
               partition_rbound_datum_cmp(partsupfunc,
                            partcollation,
                            boundinfo->datums[off],
                            boundinfo->kind[off],
                            values, nvalues));

          /*
           * We can treat 'off' as the offset of the smallest bound
           * to be included in the result, if we know it is the
           * upper bound of the partition in which the lookup value
           * could possibly exist.  One case it couldn't is if the
           * bound, or precisely the matched portion of its prefix,
           * is not inclusive.
           */
          if (boundinfo->kind[off][nvalues] ==
            PARTITION_RANGE_DATUM_MINVALUE)
            off++;

          minoff = off;

          /*
           * Now find smallest bound that's greater than the lookup
           * value.
           */
          off = saved_off;
          while (off < boundinfo->ndatums - 1)
          {
            int32   cmpval;

            cmpval = partition_rbound_datum_cmp(partsupfunc,
                              partcollation,
                              boundinfo->datums[off + 1],
                              boundinfo->kind[off + 1],
                              values, nvalues);
            if (cmpval != 0)
              break;
            off++;
          }

          Assert(0 ==
               partition_rbound_datum_cmp(partsupfunc,
                            partcollation,
                            boundinfo->datums[off],
                            boundinfo->kind[off],
                            values, nvalues));

          /*
           * off + 1, then would be the offset of the greatest bound
           * to be included in the result.
           */
          maxoff = off + 1;
        }

        Assert(minoff >= 0 && maxoff >= 0);
        result->bound_offsets = bms_add_range(NULL, minoff, maxoff);
      }
      else
      {
        /*
         * The lookup value falls in the range between some bounds in
         * boundinfo.  'off' would be the offset of the greatest bound
         * that is <= lookup value, so add off + 1 to the result
         * instead as the offset of the upper bound of the only
         * partition that may contain the lookup value.  If 'off' is
         * -1 indicating that all bounds are greater, then we simply
         * end up adding the first bound's offset, that is, 0.
         */
        result->bound_offsets = bms_make_singleton(off + 1);
      }

      return result;

    case BTGreaterEqualStrategyNumber:
      inclusive = true;
      /* fall through */
    case BTGreaterStrategyNumber:

      /*
       * Look for the smallest bound that is > or >= lookup value and
       * set minoff to its offset.
       */
      off = partition_range_datum_bsearch(partsupfunc,
                        partcollation,
                        boundinfo,
                        nvalues, values,
                        &is_equal);
      if (off < 0)
      {
        /*
         * All bounds are greater than the lookup value, so include
         * all of them in the result.
         */
        minoff = 0;
      }
      else
      {
        if (is_equal && nvalues < partnatts)
        {
          /*
           * Since the lookup value contains only a prefix of keys,
           * we must find other bounds that may also match the
           * prefix.  partition_range_datum_bsearch() returns the
           * offset of one of them, find others by checking adjacent
           * bounds.
           *
           * Based on whether the lookup values are inclusive or
           * not, we must either include the indexes of all such
           * bounds in the result (that is, set minoff to the index
           * of smallest such bound) or find the smallest one that's
           * greater than the lookup values and set minoff to that.
           */
          while (off >= 1 && off < boundinfo->ndatums - 1)
          {
            int32   cmpval;
            int     nextoff;

            nextoff = inclusive ? off - 1 : off + 1;
            cmpval =
              partition_rbound_datum_cmp(partsupfunc,
                             partcollation,
                             boundinfo->datums[nextoff],
                             boundinfo->kind[nextoff],
                             values, nvalues);
            if (cmpval != 0)
              break;

            off = nextoff;
          }

          Assert(0 ==
               partition_rbound_datum_cmp(partsupfunc,
                            partcollation,
                            boundinfo->datums[off],
                            boundinfo->kind[off],
                            values, nvalues));

          minoff = inclusive ? off : off + 1;
        }
        else
        {

          /*
           * lookup value falls in the range between some bounds in
           * boundinfo.  off would be the offset of the greatest
           * bound that is <= lookup value, so add off + 1 to the
           * result instead as the offset of the upper bound of the
           * smallest partition that may contain the lookup value.
           */
          minoff = off + 1;
        }
      }
      break;

    case BTLessEqualStrategyNumber:
      inclusive = true;
      /* fall through */
    case BTLessStrategyNumber:

      /*
       * Look for the greatest bound that is < or <= lookup value and
       * set maxoff to its offset.
       */
      off = partition_range_datum_bsearch(partsupfunc,
                        partcollation,
                        boundinfo,
                        nvalues, values,
                        &is_equal);
      if (off >= 0)
      {
        /*
         * See the comment above.
         */
        if (is_equal && nvalues < partnatts)
        {
          while (off >= 1 && off < boundinfo->ndatums - 1)
          {
            int32   cmpval;
            int     nextoff;

            nextoff = inclusive ? off + 1 : off - 1;
            cmpval = partition_rbound_datum_cmp(partsupfunc,
                              partcollation,
                              boundinfo->datums[nextoff],
                              boundinfo->kind[nextoff],
                              values, nvalues);
            if (cmpval != 0)
              break;

            off = nextoff;
          }

          Assert(0 ==
               partition_rbound_datum_cmp(partsupfunc,
                            partcollation,
                            boundinfo->datums[off],
                            boundinfo->kind[off],
                            values, nvalues));

          maxoff = inclusive ? off + 1 : off;
        }

        /*
         * The lookup value falls in the range between some bounds in
         * boundinfo.  'off' would be the offset of the greatest bound
         * that is <= lookup value, so add off + 1 to the result
         * instead as the offset of the upper bound of the greatest
         * partition that may contain lookup value.  If the lookup
         * value had exactly matched the bound, but it isn't
         * inclusive, no need add the adjacent partition.
         */
        else if (!is_equal || inclusive)
          maxoff = off + 1;
        else
          maxoff = off;
      }
      else
      {
        /*
         * 'off' is -1 indicating that all bounds are greater, so just
         * set the first bound's offset as maxoff.
         */
        maxoff = off + 1;
      }
      break;

    default:
      elog(ERROR, "invalid strategy number %d", opstrategy);
      break;
  }

  Assert(minoff >= 0 && minoff <= boundinfo->ndatums);
  Assert(maxoff >= 0 && maxoff <= boundinfo->ndatums);

  /*
   * If the smallest partition to return has MINVALUE (negative infinity) as
   * its lower bound, increment it to point to the next finite bound
   * (supposedly its upper bound), so that we don't inadvertently end up
   * scanning the default partition.
   */
  if (minoff < boundinfo->ndatums && partindices[minoff] < 0)
  {
    int     lastkey = nvalues - 1;

    if (boundinfo->kind[minoff][lastkey] ==
      PARTITION_RANGE_DATUM_MINVALUE)
    {
      minoff++;
      Assert(boundinfo->indexes[minoff] >= 0);
    }
  }

  /*
   * If the previous greatest partition has MAXVALUE (positive infinity) as
   * its upper bound (something only possible to do with multi-column range
   * partitioning), we scan switch to it as the greatest partition to
   * return.  Again, so that we don't inadvertently end up scanning the
   * default partition.
   */
  if (maxoff >= 1 && partindices[maxoff] < 0)
  {
    int     lastkey = nvalues - 1;

    if (boundinfo->kind[maxoff - 1][lastkey] ==
      PARTITION_RANGE_DATUM_MAXVALUE)
    {
      maxoff--;
      Assert(boundinfo->indexes[maxoff] >= 0);
    }
  }

  Assert(minoff >= 0 && maxoff >= 0);
  if (minoff <= maxoff)
    result->bound_offsets = bms_add_range(NULL, minoff, maxoff);

  return result;
}

/*
 * pull_exec_paramids
 *    Returns a Bitmapset containing the paramids of all Params with
 *    paramkind = PARAM_EXEC in 'expr'.
 */
static Bitmapset *
pull_exec_paramids(Expr *expr)
{
  Bitmapset  *result = NULL;

  (void) pull_exec_paramids_walker((Node *) expr, &result);

  return result;
}

static bool
pull_exec_paramids_walker(Node *node, Bitmapset **context)
{
  if (node == NULL)
    return false;
  if (IsA(node, Param))
  {
    Param    *param = (Param *) node;

    if (param->paramkind == PARAM_EXEC)
      *context = bms_add_member(*context, param->paramid);
    return false;
  }
  return expression_tree_walker(node, pull_exec_paramids_walker, context);
}

/*
 * get_partkey_exec_paramids
 *    Loop through given pruning steps and find out which exec Params
 *    are used.
 *
 * Returns a Bitmapset of Param IDs.
 */
static Bitmapset *
get_partkey_exec_paramids(List *steps)
{
  Bitmapset  *execparamids = NULL;
  ListCell   *lc;

  foreach(lc, steps)
  {
    PartitionPruneStepOp *step = (PartitionPruneStepOp *) lfirst(lc);
    ListCell   *lc2;

    if (!IsA(step, PartitionPruneStepOp))
      continue;

    foreach(lc2, step->exprs)
    {
      Expr     *expr = lfirst(lc2);

      /* We can be quick for plain Consts */
      if (!IsA(expr, Const))
        execparamids = bms_join(execparamids,
                    pull_exec_paramids(expr));
    }
  }

  return execparamids;
}

/*
 * perform_pruning_base_step
 *    Determines the indexes of datums that satisfy conditions specified in
 *    'opstep'.
 *
 * Result also contains whether special null-accepting and/or default
 * partition need to be scanned.
 */
static PruneStepResult *
perform_pruning_base_step(PartitionPruneContext *context,
              PartitionPruneStepOp *opstep)
{
  ListCell   *lc1,
         *lc2;
  int     keyno,
        nvalues;
  Datum   values[PARTITION_MAX_KEYS];
  FmgrInfo   *partsupfunc;
  int     stateidx;

  /*
   * There better be the same number of expressions and compare functions.
   */
  Assert(list_length(opstep->exprs) == list_length(opstep->cmpfns));

  nvalues = 0;
  lc1 = list_head(opstep->exprs);
  lc2 = list_head(opstep->cmpfns);

  /*
   * Generate the partition lookup key that will be used by one of the
   * get_matching_*_bounds functions called below.
   */
  for (keyno = 0; keyno < context->partnatts; keyno++)
  {
    /*
     * For hash partitioning, it is possible that values of some keys are
     * not provided in operator clauses, but instead the planner found
     * that they appeared in a IS NULL clause.
     */
    if (bms_is_member(keyno, opstep->nullkeys))
      continue;

    /*
     * For range partitioning, we must only perform pruning with values
     * for either all partition keys or a prefix thereof.
     */
    if (keyno > nvalues && context->strategy == PARTITION_STRATEGY_RANGE)
      break;

    if (lc1 != NULL)
    {
      Expr     *expr;
      Datum   datum;
      bool    isnull;
      Oid     cmpfn;

      expr = lfirst(lc1);
      stateidx = PruneCxtStateIdx(context->partnatts,
                    opstep->step.step_id, keyno);
      partkey_datum_from_expr(context, expr, stateidx,
                  &datum, &isnull);

      /*
       * Since we only allow strict operators in pruning steps, any
       * null-valued comparison value must cause the comparison to fail,
       * so that no partitions could match.
       */
      if (isnull)
      {
        PruneStepResult *result;

        result = (PruneStepResult *) palloc(sizeof(PruneStepResult));
        result->bound_offsets = NULL;
        result->scan_default = false;
        result->scan_null = false;

        return result;
      }

      /* Set up the stepcmpfuncs entry, unless we already did */
      cmpfn = lfirst_oid(lc2);
      Assert(OidIsValid(cmpfn));
      if (cmpfn != context->stepcmpfuncs[stateidx].fn_oid)
      {
        /*
         * If the needed support function is the same one cached in
         * the relation's partition key, copy the cached FmgrInfo.
         * Otherwise (i.e., when we have a cross-type comparison), an
         * actual lookup is required.
         */
        if (cmpfn == context->partsupfunc[keyno].fn_oid)
          fmgr_info_copy(&context->stepcmpfuncs[stateidx],
                   &context->partsupfunc[keyno],
                   context->ppccontext);
        else
          fmgr_info_cxt(cmpfn, &context->stepcmpfuncs[stateidx],
                  context->ppccontext);
      }

      values[keyno] = datum;
      nvalues++;

      lc1 = lnext(opstep->exprs, lc1);
      lc2 = lnext(opstep->cmpfns, lc2);
    }
  }

  /*
   * Point partsupfunc to the entry for the 0th key of this step; the
   * additional support functions, if any, follow consecutively.
   */
  stateidx = PruneCxtStateIdx(context->partnatts, opstep->step.step_id, 0);
  partsupfunc = &context->stepcmpfuncs[stateidx];

  switch (context->strategy)
  {
    case PARTITION_STRATEGY_HASH:
      return get_matching_hash_bounds(context,
                      opstep->opstrategy,
                      values, nvalues,
                      partsupfunc,
                      opstep->nullkeys);

    case PARTITION_STRATEGY_LIST:
      return get_matching_list_bounds(context,
                      opstep->opstrategy,
                      values[0], nvalues,
                      &partsupfunc[0],
                      opstep->nullkeys);

    case PARTITION_STRATEGY_RANGE:
      return get_matching_range_bounds(context,
                       opstep->opstrategy,
                       values, nvalues,
                       partsupfunc,
                       opstep->nullkeys);

    default:
      elog(ERROR, "unexpected partition strategy: %d",
         (int) context->strategy);
      break;
  }

  return NULL;
}

/*
 * perform_pruning_combine_step
 *    Determines the indexes of datums obtained by combining those given
 *    by the steps identified by cstep->source_stepids using the specified
 *    combination method
 *
 * Since cstep may refer to the result of earlier steps, we also receive
 * step_results here.
 */
static PruneStepResult *
perform_pruning_combine_step(PartitionPruneContext *context,
               PartitionPruneStepCombine *cstep,
               PruneStepResult **step_results)
{
  PruneStepResult *result = (PruneStepResult *) palloc0(sizeof(PruneStepResult));
  bool    firststep;
  ListCell   *lc1;

  /*
   * A combine step without any source steps is an indication to not perform
   * any partition pruning.  Return all datum indexes in that case.
   */
  if (cstep->source_stepids == NIL)
  {
    PartitionBoundInfo boundinfo = context->boundinfo;

    result->bound_offsets =
      bms_add_range(NULL, 0, boundinfo->nindexes - 1);
    result->scan_default = partition_bound_has_default(boundinfo);
    result->scan_null = partition_bound_accepts_nulls(boundinfo);
    return result;
  }

  switch (cstep->combineOp)
  {
    case PARTPRUNE_COMBINE_UNION:
      foreach(lc1, cstep->source_stepids)
      {
        int     step_id = lfirst_int(lc1);
        PruneStepResult *step_result;

        /*
         * step_results[step_id] must contain a valid result, which is
         * confirmed by the fact that cstep's step_id is greater than
         * step_id and the fact that results of the individual steps
         * are evaluated in sequence of their step_ids.
         */
        if (step_id >= cstep->step.step_id)
          elog(ERROR, "invalid pruning combine step argument");
        step_result = step_results[step_id];
        Assert(step_result != NULL);

        /* Record any additional datum indexes from this step */
        result->bound_offsets = bms_add_members(result->bound_offsets,
                            step_result->bound_offsets);

        /* Update whether to scan null and default partitions. */
        if (!result->scan_null)
          result->scan_null = step_result->scan_null;
        if (!result->scan_default)
          result->scan_default = step_result->scan_default;
      }
      break;

    case PARTPRUNE_COMBINE_INTERSECT:
      firststep = true;
      foreach(lc1, cstep->source_stepids)
      {
        int     step_id = lfirst_int(lc1);
        PruneStepResult *step_result;

        if (step_id >= cstep->step.step_id)
          elog(ERROR, "invalid pruning combine step argument");
        step_result = step_results[step_id];
        Assert(step_result != NULL);

        if (firststep)
        {
          /* Copy step's result the first time. */
          result->bound_offsets =
            bms_copy(step_result->bound_offsets);
          result->scan_null = step_result->scan_null;
          result->scan_default = step_result->scan_default;
          firststep = false;
        }
        else
        {
          /* Record datum indexes common to both steps */
          result->bound_offsets =
            bms_int_members(result->bound_offsets,
                    step_result->bound_offsets);

          /* Update whether to scan null and default partitions. */
          if (result->scan_null)
            result->scan_null = step_result->scan_null;
          if (result->scan_default)
            result->scan_default = step_result->scan_default;
        }
      }
      break;
  }

  return result;
}

/*
 * match_boolean_partition_clause
 *
 * If we're able to match the clause to the partition key as specially-shaped
 * boolean clause, set *outconst to a Const containing a true, false or NULL
 * value, set *notclause according to if the clause was in the "not" form,
 * i.e. "IS NOT TRUE", "IS NOT FALSE" or "IS NOT UNKNOWN" and return
 * PARTCLAUSE_MATCH_CLAUSE for "IS [NOT] (TRUE|FALSE)" clauses and
 * PARTCLAUSE_MATCH_NULLNESS for "IS [NOT] UNKNOWN" clauses.  Otherwise,
 * return PARTCLAUSE_UNSUPPORTED if the clause cannot be used for partition
 * pruning, and PARTCLAUSE_NOMATCH for supported clauses that do not match this
 * 'partkey'.
 */
static PartClauseMatchStatus
match_boolean_partition_clause(Oid partopfamily, Expr *clause, Expr *partkey,
                 Expr **outconst, bool *notclause)
{
  Expr     *leftop;

  *outconst = NULL;
  *notclause = false;

  /*
   * Partitioning currently can only use built-in AMs, so checking for
   * built-in boolean opfamilies is good enough.
   */
  if (!IsBuiltinBooleanOpfamily(partopfamily))
    return PARTCLAUSE_UNSUPPORTED;

  if (IsA(clause, BooleanTest))
  {
    BooleanTest *btest = (BooleanTest *) clause;

    leftop = btest->arg;
    if (IsA(leftop, RelabelType))
      leftop = ((RelabelType *) leftop)->arg;

    if (equal(leftop, partkey))
    {
      switch (btest->booltesttype)
      {
        case IS_NOT_TRUE:
          *notclause = true;
          /* fall through */
        case IS_TRUE:
          *outconst = (Expr *) makeBoolConst(true, false);
          return PARTCLAUSE_MATCH_CLAUSE;
        case IS_NOT_FALSE:
          *notclause = true;
          /* fall through */
        case IS_FALSE:
          *outconst = (Expr *) makeBoolConst(false, false);
          return PARTCLAUSE_MATCH_CLAUSE;
        case IS_NOT_UNKNOWN:
          *notclause = true;
          /* fall through */
        case IS_UNKNOWN:
          return PARTCLAUSE_MATCH_NULLNESS;
        default:
          return PARTCLAUSE_UNSUPPORTED;
      }
    }
    /* does not match partition key */
    return PARTCLAUSE_NOMATCH;
  }
  else
  {
    bool    is_not_clause = is_notclause(clause);

    leftop = is_not_clause ? get_notclausearg(clause) : clause;

    if (IsA(leftop, RelabelType))
      leftop = ((RelabelType *) leftop)->arg;

    /* Compare to the partition key, and make up a clause ... */
    if (equal(leftop, partkey))
      *outconst = (Expr *) makeBoolConst(!is_not_clause, false);
    else if (equal(negate_clause((Node *) leftop), partkey))
      *outconst = (Expr *) makeBoolConst(is_not_clause, false);
    else
      return PARTCLAUSE_NOMATCH;

    return PARTCLAUSE_MATCH_CLAUSE;
  }
}

/*
 * partkey_datum_from_expr
 *    Evaluate expression for potential partition pruning
 *
 * Evaluate 'expr'; set *value and *isnull to the resulting Datum and nullflag.
 *
 * If expr isn't a Const, its ExprState is in stateidx of the context
 * exprstate array.
 *
 * Note that the evaluated result may be in the per-tuple memory context of
 * context->exprcontext, and we may have leaked other memory there too.
 * This memory must be recovered by resetting that ExprContext after
 * we're done with the pruning operation (see execPartition.c).
 */
static void
partkey_datum_from_expr(PartitionPruneContext *context,
            Expr *expr, int stateidx,
            Datum *value, bool *isnull)
{
  if (IsA(expr, Const))
  {
    /* We can always determine the value of a constant */
    Const    *con = (Const *) expr;

    *value = con->constvalue;
    *isnull = con->constisnull;
  }
  else
  {
    ExprState  *exprstate;
    ExprContext *ectx;

    /*
     * We should never see a non-Const in a step unless the caller has
     * passed a valid ExprContext.
     */
    Assert(context->exprcontext != NULL);

    exprstate = context->exprstates[stateidx];
    ectx = context->exprcontext;
    *value = ExecEvalExprSwitchContext(exprstate, ectx, isnull);
  }
}

Coverage Report

Created: 2025-08-12 06:43