setrefs.c

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/*-------------------------------------------------------------------------
 *
 * setrefs.c
 *    Post-processing of a completed plan tree: fix references to subplan
 *    vars, compute regproc values for operators, etc
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/optimizer/plan/setrefs.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "access/transam.h"
#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/optimizer.h"
#include "optimizer/pathnode.h"
#include "optimizer/planmain.h"
#include "optimizer/planner.h"
#include "optimizer/subselect.h"
#include "optimizer/tlist.h"
#include "parser/parse_relation.h"
#include "rewrite/rewriteManip.h"
#include "tcop/utility.h"
#include "utils/syscache.h"
 
 
typedef enum
{
    NRM_EQUAL,                  /* expect exact match of nullingrels */
    NRM_SUBSET,                 /* actual Var may have a subset of input */
    NRM_SUPERSET,               /* actual Var may have a superset of input */
} NullingRelsMatch;
 
typedef struct
{
    int         varno;          /* RT index of Var */
    AttrNumber  varattno;       /* attr number of Var */
    AttrNumber  resno;          /* TLE position of Var */
    Bitmapset  *varnullingrels; /* Var's varnullingrels */
} tlist_vinfo;
 
typedef struct
{
    List       *tlist;          /* underlying target list */
    int         num_vars;       /* number of plain Var tlist entries */
    bool        has_ph_vars;    /* are there PlaceHolderVar entries? */
    bool        has_non_vars;   /* are there other entries? */
    tlist_vinfo vars[FLEXIBLE_ARRAY_MEMBER];    /* has num_vars entries */
} indexed_tlist;
 
typedef struct
{
    PlannerInfo *root;
    int         rtoffset;
    double      num_exec;
} fix_scan_expr_context;
 
typedef struct
{
    PlannerInfo *root;
    indexed_tlist *outer_itlist;
    indexed_tlist *inner_itlist;
    Index       acceptable_rel;
    int         rtoffset;
    NullingRelsMatch nrm_match;
    double      num_exec;
} fix_join_expr_context;
 
typedef struct
{
    PlannerInfo *root;
    indexed_tlist *subplan_itlist;
    int         newvarno;
    int         rtoffset;
    NullingRelsMatch nrm_match;
    double      num_exec;
} fix_upper_expr_context;
 
typedef struct
{
    PlannerInfo *root;
    indexed_tlist *subplan_itlist;
    int         newvarno;
} fix_windowagg_cond_context;
 
/* Context info for flatten_rtes_walker() */
typedef struct
{
    PlannerGlobal *glob;
    Query      *query;
} flatten_rtes_walker_context;
 
/*
 * Selecting the best alternative in an AlternativeSubPlan expression requires
 * estimating how many times that expression will be evaluated.  For an
 * expression in a plan node's targetlist, the plan's estimated number of
 * output rows is clearly what to use, but for an expression in a qual it's
 * far less clear.  Since AlternativeSubPlans aren't heavily used, we don't
 * want to expend a lot of cycles making such estimates.  What we use is twice
 * the number of output rows.  That's not entirely unfounded: we know that
 * clause_selectivity() would fall back to a default selectivity estimate
 * of 0.5 for any SubPlan, so if the qual containing the SubPlan is the last
 * to be applied (which it likely would be, thanks to order_qual_clauses()),
 * this matches what we could have estimated in a far more laborious fashion.
 * Obviously there are many other scenarios, but it's probably not worth the
 * trouble to try to improve on this estimate, especially not when we don't
 * have a better estimate for the selectivity of the SubPlan qual itself.
 */
#define NUM_EXEC_TLIST(parentplan)  ((parentplan)->plan_rows)
#define NUM_EXEC_QUAL(parentplan)   ((parentplan)->plan_rows * 2.0)
 
/*
 * Check if a Const node is a regclass value.  We accept plain OID too,
 * since a regclass Const will get folded to that type if it's an argument
 * to oideq or similar operators.  (This might result in some extraneous
 * values in a plan's list of relation dependencies, but the worst result
 * would be occasional useless replans.)
 */
#define ISREGCLASSCONST(con) \
    (((con)->consttype == REGCLASSOID || (con)->consttype == OIDOID) && \
     !(con)->constisnull)
 
#define fix_scan_list(root, lst, rtoffset, num_exec) \
    ((List *) fix_scan_expr(root, (Node *) (lst), rtoffset, num_exec))
 
static void add_rtes_to_flat_rtable(PlannerInfo *root, bool recursing);
static void flatten_unplanned_rtes(PlannerGlobal *glob, RangeTblEntry *rte);
static bool flatten_rtes_walker(Node *node, flatten_rtes_walker_context *cxt);
static void add_rte_to_flat_rtable(PlannerGlobal *glob, List *rteperminfos,
                                   RangeTblEntry *rte);
static Plan *set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset);
static Plan *set_indexonlyscan_references(PlannerInfo *root,
                                          IndexOnlyScan *plan,
                                          int rtoffset);
static Plan *set_subqueryscan_references(PlannerInfo *root,
                                         SubqueryScan *plan,
                                         int rtoffset);
static Plan *clean_up_removed_plan_level(Plan *parent, Plan *child);
static void set_foreignscan_references(PlannerInfo *root,
                                       ForeignScan *fscan,
                                       int rtoffset);
static void set_customscan_references(PlannerInfo *root,
                                      CustomScan *cscan,
                                      int rtoffset);
static Plan *set_append_references(PlannerInfo *root,
                                   Append *aplan,
                                   int rtoffset);
static Plan *set_mergeappend_references(PlannerInfo *root,
                                        MergeAppend *mplan,
                                        int rtoffset);
static void set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset);
static Relids offset_relid_set(Relids relids, int rtoffset);
static Node *fix_scan_expr(PlannerInfo *root, Node *node,
                           int rtoffset, double num_exec);
static Node *fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context);
static bool fix_scan_expr_walker(Node *node, fix_scan_expr_context *context);
static void set_join_references(PlannerInfo *root, Join *join, int rtoffset);
static void set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset);
static void set_param_references(PlannerInfo *root, Plan *plan);
static Node *convert_combining_aggrefs(Node *node, void *context);
static void set_dummy_tlist_references(Plan *plan, int rtoffset);
static indexed_tlist *build_tlist_index(List *tlist);
static Var *search_indexed_tlist_for_var(Var *var,
                                         indexed_tlist *itlist,
                                         int newvarno,
                                         int rtoffset,
                                         NullingRelsMatch nrm_match);
static Var *search_indexed_tlist_for_phv(PlaceHolderVar *phv,
                                         indexed_tlist *itlist,
                                         int newvarno,
                                         NullingRelsMatch nrm_match);
static Var *search_indexed_tlist_for_non_var(Expr *node,
                                             indexed_tlist *itlist,
                                             int newvarno);
static Var *search_indexed_tlist_for_sortgroupref(Expr *node,
                                                  Index sortgroupref,
                                                  indexed_tlist *itlist,
                                                  int newvarno);
static List *fix_join_expr(PlannerInfo *root,
                           List *clauses,
                           indexed_tlist *outer_itlist,
                           indexed_tlist *inner_itlist,
                           Index acceptable_rel,
                           int rtoffset,
                           NullingRelsMatch nrm_match,
                           double num_exec);
static Node *fix_join_expr_mutator(Node *node,
                                   fix_join_expr_context *context);
static Node *fix_upper_expr(PlannerInfo *root,
                            Node *node,
                            indexed_tlist *subplan_itlist,
                            int newvarno,
                            int rtoffset,
                            NullingRelsMatch nrm_match,
                            double num_exec);
static Node *fix_upper_expr_mutator(Node *node,
                                    fix_upper_expr_context *context);
static List *set_returning_clause_references(PlannerInfo *root,
                                             List *rlist,
                                             Plan *topplan,
                                             Index resultRelation,
                                             int rtoffset);
static List *set_windowagg_runcondition_references(PlannerInfo *root,
                                                   List *runcondition,
                                                   Plan *plan);
 
 
/*****************************************************************************
 *
 *      SUBPLAN REFERENCES
 *
 *****************************************************************************/
 
/*
 * set_plan_references
 *
 * This is the final processing pass of the planner/optimizer.  The plan
 * tree is complete; we just have to adjust some representational details
 * for the convenience of the executor:
 *
 * 1. We flatten the various subquery rangetables into a single list, and
 * zero out RangeTblEntry fields that are not useful to the executor.
 *
 * 2. We adjust Vars in scan nodes to be consistent with the flat rangetable.
 *
 * 3. We adjust Vars in upper plan nodes to refer to the outputs of their
 * subplans.
 *
 * 4. Aggrefs in Agg plan nodes need to be adjusted in some cases involving
 * partial aggregation or minmax aggregate optimization.
 *
 * 5. PARAM_MULTIEXPR Params are replaced by regular PARAM_EXEC Params,
 * now that we have finished planning all MULTIEXPR subplans.
 *
 * 6. AlternativeSubPlan expressions are replaced by just one of their
 * alternatives, using an estimate of how many times they'll be executed.
 *
 * 7. We compute regproc OIDs for operators (ie, we look up the function
 * that implements each op).
 *
 * 8. We create lists of specific objects that the plan depends on.
 * This will be used by plancache.c to drive invalidation of cached plans.
 * Relation dependencies are represented by OIDs, and everything else by
 * PlanInvalItems (this distinction is motivated by the shared-inval APIs).
 * Currently, relations, user-defined functions, and domains are the only
 * types of objects that are explicitly tracked this way.
 *
 * 9. We assign every plan node in the tree a unique ID.
 *
 * We also perform one final optimization step, which is to delete
 * SubqueryScan, Append, and MergeAppend plan nodes that aren't doing
 * anything useful.  The reason for doing this last is that
 * it can't readily be done before set_plan_references, because it would
 * break set_upper_references: the Vars in the child plan's top tlist
 * wouldn't match up with the Vars in the outer plan tree.  A SubqueryScan
 * serves a necessary function as a buffer between outer query and subquery
 * variable numbering ... but after we've flattened the rangetable this is
 * no longer a problem, since then there's only one rtindex namespace.
 * Likewise, Append and MergeAppend buffer between the parent and child vars
 * of an appendrel, but we don't need to worry about that once we've done
 * set_plan_references.
 *
 * set_plan_references recursively traverses the whole plan tree.
 *
 * The return value is normally the same Plan node passed in, but can be
 * different when the passed-in Plan is a node we decide isn't needed.
 *
 * The flattened rangetable entries are appended to root->glob->finalrtable.
 * Also, rowmarks entries are appended to root->glob->finalrowmarks, and the
 * RT indexes of ModifyTable result relations to root->glob->resultRelations,
 * and flattened AppendRelInfos are appended to root->glob->appendRelations.
 * Plan dependencies are appended to root->glob->relationOids (for relations)
 * and root->glob->invalItems (for everything else).
 *
 * Notice that we modify Plan nodes in-place, but use expression_tree_mutator
 * to process targetlist and qual expressions.  We can assume that the Plan
 * nodes were just built by the planner and are not multiply referenced, but
 * it's not so safe to assume that for expression tree nodes.
 */
Plan *
set_plan_references(PlannerInfo *root, Plan *plan)
{
    Plan       *result;
    PlannerGlobal *glob = root->glob;
    int         rtoffset = list_length(glob->finalrtable);
    ListCell   *lc;
 
    /*
     * Add all the query's RTEs to the flattened rangetable.  The live ones
     * will have their rangetable indexes increased by rtoffset.  (Additional
     * RTEs, not referenced by the Plan tree, might get added after those.)
     */
    add_rtes_to_flat_rtable(root, false);
 
    /*
     * Adjust RT indexes of PlanRowMarks and add to final rowmarks list
     */
    foreach(lc, root->rowMarks)
    {
        PlanRowMark *rc = lfirst_node(PlanRowMark, lc);
        PlanRowMark *newrc;
 
        /* sanity check on existing row marks */
        Assert(root->simple_rel_array[rc->rti] != NULL &&
               root->simple_rte_array[rc->rti] != NULL);
 
        /* flat copy is enough since all fields are scalars */
        newrc = (PlanRowMark *) palloc(sizeof(PlanRowMark));
        memcpy(newrc, rc, sizeof(PlanRowMark));
 
        /* adjust indexes ... but *not* the rowmarkId */
        newrc->rti += rtoffset;
        newrc->prti += rtoffset;
 
        glob->finalrowmarks = lappend(glob->finalrowmarks, newrc);
    }
 
    /*
     * Adjust RT indexes of AppendRelInfos and add to final appendrels list.
     * We assume the AppendRelInfos were built during planning and don't need
     * to be copied.
     */
    foreach(lc, root->append_rel_list)
    {
        AppendRelInfo *appinfo = lfirst_node(AppendRelInfo, lc);
 
        /* adjust RT indexes */
        appinfo->parent_relid += rtoffset;
        appinfo->child_relid += rtoffset;
 
        /*
         * Rather than adjust the translated_vars entries, just drop 'em.
         * Neither the executor nor EXPLAIN currently need that data.
         */
        appinfo->translated_vars = NIL;
 
        glob->appendRelations = lappend(glob->appendRelations, appinfo);
    }
 
    /* If needed, create workspace for processing AlternativeSubPlans */
    if (root->hasAlternativeSubPlans)
    {
        root->isAltSubplan = (bool *)
            palloc0(list_length(glob->subplans) * sizeof(bool));
        root->isUsedSubplan = (bool *)
            palloc0(list_length(glob->subplans) * sizeof(bool));
    }
 
    /* Now fix the Plan tree */
    result = set_plan_refs(root, plan, rtoffset);
 
    /*
     * If we have AlternativeSubPlans, it is likely that we now have some
     * unreferenced subplans in glob->subplans.  To avoid expending cycles on
     * those subplans later, get rid of them by setting those list entries to
     * NULL.  (Note: we can't do this immediately upon processing an
     * AlternativeSubPlan, because there may be multiple copies of the
     * AlternativeSubPlan, and they can get resolved differently.)
     */
    if (root->hasAlternativeSubPlans)
    {
        foreach(lc, glob->subplans)
        {
            int         ndx = foreach_current_index(lc);
 
            /*
             * If it was used by some AlternativeSubPlan in this query level,
             * but wasn't selected as best by any AlternativeSubPlan, then we
             * don't need it.  Do not touch subplans that aren't parts of
             * AlternativeSubPlans.
             */
            if (root->isAltSubplan[ndx] && !root->isUsedSubplan[ndx])
                lfirst(lc) = NULL;
        }
    }
 
    return result;
}
 
/*
 * Extract RangeTblEntries from the plan's rangetable, and add to flat rtable
 *
 * This can recurse into subquery plans; "recursing" is true if so.
 *
 * This also seems like a good place to add the query's RTEPermissionInfos to
 * the flat rteperminfos.
 */
static void
add_rtes_to_flat_rtable(PlannerInfo *root, bool recursing)
{
    PlannerGlobal *glob = root->glob;
    Index       rti;
    ListCell   *lc;
 
    /*
     * Add the query's own RTEs to the flattened rangetable.
     *
     * At top level, we must add all RTEs so that their indexes in the
     * flattened rangetable match up with their original indexes.  When
     * recursing, we only care about extracting relation RTEs (and subquery
     * RTEs that were once relation RTEs).
     */
    foreach(lc, root->parse->rtable)
    {
        RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
 
        if (!recursing || rte->rtekind == RTE_RELATION ||
            (rte->rtekind == RTE_SUBQUERY && OidIsValid(rte->relid)))
            add_rte_to_flat_rtable(glob, root->parse->rteperminfos, rte);
    }
 
    /*
     * If there are any dead subqueries, they are not referenced in the Plan
     * tree, so we must add RTEs contained in them to the flattened rtable
     * separately.  (If we failed to do this, the executor would not perform
     * expected permission checks for tables mentioned in such subqueries.)
     *
     * Note: this pass over the rangetable can't be combined with the previous
     * one, because that would mess up the numbering of the live RTEs in the
     * flattened rangetable.
     */
    rti = 1;
    foreach(lc, root->parse->rtable)
    {
        RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
 
        /*
         * We should ignore inheritance-parent RTEs: their contents have been
         * pulled up into our rangetable already.  Also ignore any subquery
         * RTEs without matching RelOptInfos, as they likewise have been
         * pulled up.
         */
        if (rte->rtekind == RTE_SUBQUERY && !rte->inh &&
            rti < root->simple_rel_array_size)
        {
            RelOptInfo *rel = root->simple_rel_array[rti];
 
            if (rel != NULL)
            {
                Assert(rel->relid == rti);  /* sanity check on array */
 
                /*
                 * The subquery might never have been planned at all, if it
                 * was excluded on the basis of self-contradictory constraints
                 * in our query level.  In this case apply
                 * flatten_unplanned_rtes.
                 *
                 * If it was planned but the result rel is dummy, we assume
                 * that it has been omitted from our plan tree (see
                 * set_subquery_pathlist), and recurse to pull up its RTEs.
                 *
                 * Otherwise, it should be represented by a SubqueryScan node
                 * somewhere in our plan tree, and we'll pull up its RTEs when
                 * we process that plan node.
                 *
                 * However, if we're recursing, then we should pull up RTEs
                 * whether the subquery is dummy or not, because we've found
                 * that some upper query level is treating this one as dummy,
                 * and so we won't scan this level's plan tree at all.
                 */
                if (rel->subroot == NULL)
                    flatten_unplanned_rtes(glob, rte);
                else if (recursing ||
                         IS_DUMMY_REL(fetch_upper_rel(rel->subroot,
                                                      UPPERREL_FINAL, NULL)))
                    add_rtes_to_flat_rtable(rel->subroot, true);
            }
        }
        rti++;
    }
}
 
/*
 * Extract RangeTblEntries from a subquery that was never planned at all
 */
 
static void
flatten_unplanned_rtes(PlannerGlobal *glob, RangeTblEntry *rte)
{
    flatten_rtes_walker_context cxt = {glob, rte->subquery};
 
    /* Use query_tree_walker to find all RTEs in the parse tree */
    (void) query_tree_walker(rte->subquery,
                             flatten_rtes_walker,
                             &cxt,
                             QTW_EXAMINE_RTES_BEFORE);
}
 
static bool
flatten_rtes_walker(Node *node, flatten_rtes_walker_context *cxt)
{
    if (node == NULL)
        return false;
    if (IsA(node, RangeTblEntry))
    {
        RangeTblEntry *rte = (RangeTblEntry *) node;
 
        /* As above, we need only save relation RTEs and former relations */
        if (rte->rtekind == RTE_RELATION ||
            (rte->rtekind == RTE_SUBQUERY && OidIsValid(rte->relid)))
            add_rte_to_flat_rtable(cxt->glob, cxt->query->rteperminfos, rte);
        return false;
    }
    if (IsA(node, Query))
    {
        /*
         * Recurse into subselects.  Must update cxt->query to this query so
         * that the rtable and rteperminfos correspond with each other.
         */
        Query      *save_query = cxt->query;
        bool        result;
 
        cxt->query = (Query *) node;
        result = query_tree_walker((Query *) node,
                                   flatten_rtes_walker,
                                   cxt,
                                   QTW_EXAMINE_RTES_BEFORE);
        cxt->query = save_query;
        return result;
    }
    return expression_tree_walker(node, flatten_rtes_walker, cxt);
}
 
/*
 * Add (a copy of) the given RTE to the final rangetable and also the
 * corresponding RTEPermissionInfo, if any, to final rteperminfos.
 *
 * In the flat rangetable, we zero out substructure pointers that are not
 * needed by the executor; this reduces the storage space and copying cost
 * for cached plans.  We keep only the ctename, alias, eref Alias fields,
 * which are needed by EXPLAIN, and perminfoindex which is needed by the
 * executor to fetch the RTE's RTEPermissionInfo.
 */
static void
add_rte_to_flat_rtable(PlannerGlobal *glob, List *rteperminfos,
                       RangeTblEntry *rte)
{
    RangeTblEntry *newrte;
 
    /* flat copy to duplicate all the scalar fields */
    newrte = (RangeTblEntry *) palloc(sizeof(RangeTblEntry));
    memcpy(newrte, rte, sizeof(RangeTblEntry));
 
    /* zap unneeded sub-structure */
    newrte->tablesample = NULL;
    newrte->subquery = NULL;
    newrte->joinaliasvars = NIL;
    newrte->joinleftcols = NIL;
    newrte->joinrightcols = NIL;
    newrte->join_using_alias = NULL;
    newrte->functions = NIL;
    newrte->tablefunc = NULL;
    newrte->values_lists = NIL;
    newrte->coltypes = NIL;
    newrte->coltypmods = NIL;
    newrte->colcollations = NIL;
    newrte->groupexprs = NIL;
    newrte->securityQuals = NIL;
 
    glob->finalrtable = lappend(glob->finalrtable, newrte);
 
    /*
     * If it's a plain relation RTE (or a subquery that was once a view
     * reference), add the relation OID to relationOids.  Also add its new RT
     * index to the set of relations to be potentially accessed during
     * execution.
     *
     * We do this even though the RTE might be unreferenced in the plan tree;
     * this would correspond to cases such as views that were expanded, child
     * tables that were eliminated by constraint exclusion, etc. Schema
     * invalidation on such a rel must still force rebuilding of the plan.
     *
     * Note we don't bother to avoid making duplicate list entries.  We could,
     * but it would probably cost more cycles than it would save.
     */
    if (newrte->rtekind == RTE_RELATION ||
        (newrte->rtekind == RTE_SUBQUERY && OidIsValid(newrte->relid)))
    {
        glob->relationOids = lappend_oid(glob->relationOids, newrte->relid);
        glob->allRelids = bms_add_member(glob->allRelids,
                                         list_length(glob->finalrtable));
    }
 
    /*
     * Add a copy of the RTEPermissionInfo, if any, corresponding to this RTE
     * to the flattened global list.
     */
    if (rte->perminfoindex > 0)
    {
        RTEPermissionInfo *perminfo;
        RTEPermissionInfo *newperminfo;
 
        /* Get the existing one from this query's rteperminfos. */
        perminfo = getRTEPermissionInfo(rteperminfos, newrte);
 
        /*
         * Add a new one to finalrteperminfos and copy the contents of the
         * existing one into it.  Note that addRTEPermissionInfo() also
         * updates newrte->perminfoindex to point to newperminfo in
         * finalrteperminfos.
         */
        newrte->perminfoindex = 0;  /* expected by addRTEPermissionInfo() */
        newperminfo = addRTEPermissionInfo(&glob->finalrteperminfos, newrte);
        memcpy(newperminfo, perminfo, sizeof(RTEPermissionInfo));
    }
}
 
/*
 * set_plan_refs: recurse through the Plan nodes of a single subquery level
 */
static Plan *
set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
{
    ListCell   *l;
 
    if (plan == NULL)
        return NULL;
 
    /* Assign this node a unique ID. */
    plan->plan_node_id = root->glob->lastPlanNodeId++;
 
    /*
     * Plan-type-specific fixes
     */
    switch (nodeTag(plan))
    {
        case T_SeqScan:
            {
                SeqScan    *splan = (SeqScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                splan->scan.plan.targetlist =
                    fix_scan_list(root, splan->scan.plan.targetlist,
                                  rtoffset, NUM_EXEC_TLIST(plan));
                splan->scan.plan.qual =
                    fix_scan_list(root, splan->scan.plan.qual,
                                  rtoffset, NUM_EXEC_QUAL(plan));
            }
            break;
        case T_SampleScan:
            {
                SampleScan *splan = (SampleScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                splan->scan.plan.targetlist =
                    fix_scan_list(root, splan->scan.plan.targetlist,
                                  rtoffset, NUM_EXEC_TLIST(plan));
                splan->scan.plan.qual =
                    fix_scan_list(root, splan->scan.plan.qual,
                                  rtoffset, NUM_EXEC_QUAL(plan));
                splan->tablesample = (TableSampleClause *)
                    fix_scan_expr(root, (Node *) splan->tablesample,
                                  rtoffset, 1);
            }
            break;
        case T_IndexScan:
            {
                IndexScan  *splan = (IndexScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                splan->scan.plan.targetlist =
                    fix_scan_list(root, splan->scan.plan.targetlist,
                                  rtoffset, NUM_EXEC_TLIST(plan));
                splan->scan.plan.qual =
                    fix_scan_list(root, splan->scan.plan.qual,
                                  rtoffset, NUM_EXEC_QUAL(plan));
                splan->indexqual =
                    fix_scan_list(root, splan->indexqual,
                                  rtoffset, 1);
                splan->indexqualorig =
                    fix_scan_list(root, splan->indexqualorig,
                                  rtoffset, NUM_EXEC_QUAL(plan));
                splan->indexorderby =
                    fix_scan_list(root, splan->indexorderby,
                                  rtoffset, 1);
                splan->indexorderbyorig =
                    fix_scan_list(root, splan->indexorderbyorig,
                                  rtoffset, NUM_EXEC_QUAL(plan));
            }
            break;
        case T_IndexOnlyScan:
            {
                IndexOnlyScan *splan = (IndexOnlyScan *) plan;
 
                return set_indexonlyscan_references(root, splan, rtoffset);
            }
            break;
        case T_BitmapIndexScan:
            {
                BitmapIndexScan *splan = (BitmapIndexScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                /* no need to fix targetlist and qual */
                Assert(splan->scan.plan.targetlist == NIL);
                Assert(splan->scan.plan.qual == NIL);
                splan->indexqual =
                    fix_scan_list(root, splan->indexqual, rtoffset, 1);
                splan->indexqualorig =
                    fix_scan_list(root, splan->indexqualorig,
                                  rtoffset, NUM_EXEC_QUAL(plan));
            }
            break;
        case T_BitmapHeapScan:
            {
                BitmapHeapScan *splan = (BitmapHeapScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                splan->scan.plan.targetlist =
                    fix_scan_list(root, splan->scan.plan.targetlist,
                                  rtoffset, NUM_EXEC_TLIST(plan));
                splan->scan.plan.qual =
                    fix_scan_list(root, splan->scan.plan.qual,
                                  rtoffset, NUM_EXEC_QUAL(plan));
                splan->bitmapqualorig =
                    fix_scan_list(root, splan->bitmapqualorig,
                                  rtoffset, NUM_EXEC_QUAL(plan));
            }
            break;
        case T_TidScan:
            {
                TidScan    *splan = (TidScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                splan->scan.plan.targetlist =
                    fix_scan_list(root, splan->scan.plan.targetlist,
                                  rtoffset, NUM_EXEC_TLIST(plan));
                splan->scan.plan.qual =
                    fix_scan_list(root, splan->scan.plan.qual,
                                  rtoffset, NUM_EXEC_QUAL(plan));
                splan->tidquals =
                    fix_scan_list(root, splan->tidquals,
                                  rtoffset, 1);
            }
            break;
        case T_TidRangeScan:
            {
                TidRangeScan *splan = (TidRangeScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                splan->scan.plan.targetlist =
                    fix_scan_list(root, splan->scan.plan.targetlist,
                                  rtoffset, NUM_EXEC_TLIST(plan));
                splan->scan.plan.qual =
                    fix_scan_list(root, splan->scan.plan.qual,
                                  rtoffset, NUM_EXEC_QUAL(plan));
                splan->tidrangequals =
                    fix_scan_list(root, splan->tidrangequals,
                                  rtoffset, 1);
            }
            break;
        case T_SubqueryScan:
            /* Needs special treatment, see comments below */
            return set_subqueryscan_references(root,
                                               (SubqueryScan *) plan,
                                               rtoffset);
        case T_FunctionScan:
            {
                FunctionScan *splan = (FunctionScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                splan->scan.plan.targetlist =
                    fix_scan_list(root, splan->scan.plan.targetlist,
                                  rtoffset, NUM_EXEC_TLIST(plan));
                splan->scan.plan.qual =
                    fix_scan_list(root, splan->scan.plan.qual,
                                  rtoffset, NUM_EXEC_QUAL(plan));
                splan->functions =
                    fix_scan_list(root, splan->functions, rtoffset, 1);
            }
            break;
        case T_TableFuncScan:
            {
                TableFuncScan *splan = (TableFuncScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                splan->scan.plan.targetlist =
                    fix_scan_list(root, splan->scan.plan.targetlist,
                                  rtoffset, NUM_EXEC_TLIST(plan));
                splan->scan.plan.qual =
                    fix_scan_list(root, splan->scan.plan.qual,
                                  rtoffset, NUM_EXEC_QUAL(plan));
                splan->tablefunc = (TableFunc *)
                    fix_scan_expr(root, (Node *) splan->tablefunc,
                                  rtoffset, 1);
            }
            break;
        case T_ValuesScan:
            {
                ValuesScan *splan = (ValuesScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                splan->scan.plan.targetlist =
                    fix_scan_list(root, splan->scan.plan.targetlist,
                                  rtoffset, NUM_EXEC_TLIST(plan));
                splan->scan.plan.qual =
                    fix_scan_list(root, splan->scan.plan.qual,
                                  rtoffset, NUM_EXEC_QUAL(plan));
                splan->values_lists =
                    fix_scan_list(root, splan->values_lists,
                                  rtoffset, 1);
            }
            break;
        case T_CteScan:
            {
                CteScan    *splan = (CteScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                splan->scan.plan.targetlist =
                    fix_scan_list(root, splan->scan.plan.targetlist,
                                  rtoffset, NUM_EXEC_TLIST(plan));
                splan->scan.plan.qual =
                    fix_scan_list(root, splan->scan.plan.qual,
                                  rtoffset, NUM_EXEC_QUAL(plan));
            }
            break;
        case T_NamedTuplestoreScan:
            {
                NamedTuplestoreScan *splan = (NamedTuplestoreScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                splan->scan.plan.targetlist =
                    fix_scan_list(root, splan->scan.plan.targetlist,
                                  rtoffset, NUM_EXEC_TLIST(plan));
                splan->scan.plan.qual =
                    fix_scan_list(root, splan->scan.plan.qual,
                                  rtoffset, NUM_EXEC_QUAL(plan));
            }
            break;
        case T_WorkTableScan:
            {
                WorkTableScan *splan = (WorkTableScan *) plan;
 
                splan->scan.scanrelid += rtoffset;
                splan->scan.plan.targetlist =
                    fix_scan_list(root, splan->scan.plan.targetlist,
                                  rtoffset, NUM_EXEC_TLIST(plan));
                splan->scan.plan.qual =
                    fix_scan_list(root, splan->scan.plan.qual,
                                  rtoffset, NUM_EXEC_QUAL(plan));
            }
            break;
        case T_ForeignScan:
            set_foreignscan_references(root, (ForeignScan *) plan, rtoffset);
            break;
        case T_CustomScan:
            set_customscan_references(root, (CustomScan *) plan, rtoffset);
            break;
 
        case T_NestLoop:
        case T_MergeJoin:
        case T_HashJoin:
            set_join_references(root, (Join *) plan, rtoffset);
            break;
 
        case T_Gather:
        case T_GatherMerge:
            {
                set_upper_references(root, plan, rtoffset);
                set_param_references(root, plan);
            }
            break;
 
        case T_Hash:
            set_hash_references(root, plan, rtoffset);
            break;
 
        case T_Memoize:
            {
                Memoize    *mplan = (Memoize *) plan;
 
                /*
                 * Memoize does not evaluate its targetlist.  It just uses the
                 * same targetlist from its outer subnode.
                 */
                set_dummy_tlist_references(plan, rtoffset);
 
                mplan->param_exprs = fix_scan_list(root, mplan->param_exprs,
                                                   rtoffset,
                                                   NUM_EXEC_TLIST(plan));
                break;
            }
 
        case T_Material:
        case T_Sort:
        case T_IncrementalSort:
        case T_Unique:
        case T_SetOp:
 
            /*
             * These plan types don't actually bother to evaluate their
             * targetlists, because they just return their unmodified input
             * tuples.  Even though the targetlist won't be used by the
             * executor, we fix it up for possible use by EXPLAIN (not to
             * mention ease of debugging --- wrong varnos are very confusing).
             */
            set_dummy_tlist_references(plan, rtoffset);
 
            /*
             * Since these plan types don't check quals either, we should not
             * find any qual expression attached to them.
             */
            Assert(plan->qual == NIL);
            break;
        case T_LockRows:
            {
                LockRows   *splan = (LockRows *) plan;
 
                /*
                 * Like the plan types above, LockRows doesn't evaluate its
                 * tlist or quals.  But we have to fix up the RT indexes in
                 * its rowmarks.
                 */
                set_dummy_tlist_references(plan, rtoffset);
                Assert(splan->plan.qual == NIL);
 
                foreach(l, splan->rowMarks)
                {
                    PlanRowMark *rc = (PlanRowMark *) lfirst(l);
 
                    rc->rti += rtoffset;
                    rc->prti += rtoffset;
                }
            }
            break;
        case T_Limit:
            {
                Limit      *splan = (Limit *) plan;
 
                /*
                 * Like the plan types above, Limit doesn't evaluate its tlist
                 * or quals.  It does have live expressions for limit/offset,
                 * however; and those cannot contain subplan variable refs, so
                 * fix_scan_expr works for them.
                 */
                set_dummy_tlist_references(plan, rtoffset);
                Assert(splan->plan.qual == NIL);
 
                splan->limitOffset =
                    fix_scan_expr(root, splan->limitOffset, rtoffset, 1);
                splan->limitCount =
                    fix_scan_expr(root, splan->limitCount, rtoffset, 1);
            }
            break;
        case T_Agg:
            {
                Agg        *agg = (Agg *) plan;
 
                /*
                 * If this node is combining partial-aggregation results, we
                 * must convert its Aggrefs to contain references to the
                 * partial-aggregate subexpressions that will be available
                 * from the child plan node.
                 */
                if (DO_AGGSPLIT_COMBINE(agg->aggsplit))
                {
                    plan->targetlist = (List *)
                        convert_combining_aggrefs((Node *) plan->targetlist,
                                                  NULL);
                    plan->qual = (List *)
                        convert_combining_aggrefs((Node *) plan->qual,
                                                  NULL);
                }
 
                set_upper_references(root, plan, rtoffset);
            }
            break;
        case T_Group:
            set_upper_references(root, plan, rtoffset);
            break;
        case T_WindowAgg:
            {
                WindowAgg  *wplan = (WindowAgg *) plan;
 
                /*
                 * Adjust the WindowAgg's run conditions by swapping the
                 * WindowFuncs references out to instead reference the Var in
                 * the scan slot so that when the executor evaluates the
                 * runCondition, it receives the WindowFunc's value from the
                 * slot that the result has just been stored into rather than
                 * evaluating the WindowFunc all over again.
                 */
                wplan->runCondition = set_windowagg_runcondition_references(root,
                                                                            wplan->runCondition,
                                                                            (Plan *) wplan);
 
                set_upper_references(root, plan, rtoffset);
 
                /*
                 * Like Limit node limit/offset expressions, WindowAgg has
                 * frame offset expressions, which cannot contain subplan
                 * variable refs, so fix_scan_expr works for them.
                 */
                wplan->startOffset =
                    fix_scan_expr(root, wplan->startOffset, rtoffset, 1);
                wplan->endOffset =
                    fix_scan_expr(root, wplan->endOffset, rtoffset, 1);
                wplan->runCondition = fix_scan_list(root,
                                                    wplan->runCondition,
                                                    rtoffset,
                                                    NUM_EXEC_TLIST(plan));
                wplan->runConditionOrig = fix_scan_list(root,
                                                        wplan->runConditionOrig,
                                                        rtoffset,
                                                        NUM_EXEC_TLIST(plan));
            }
            break;
        case T_Result:
            {
                Result     *splan = (Result *) plan;
 
                /*
                 * Result may or may not have a subplan; if not, it's more
                 * like a scan node than an upper node.
                 */
                if (splan->plan.lefttree != NULL)
                    set_upper_references(root, plan, rtoffset);
                else
                {
                    /*
                     * The tlist of a childless Result could contain
                     * unresolved ROWID_VAR Vars, in case it's representing a
                     * target relation which is completely empty because of
                     * constraint exclusion.  Replace any such Vars by null
                     * constants, as though they'd been resolved for a leaf
                     * scan node that doesn't support them.  We could have
                     * fix_scan_expr do this, but since the case is only
                     * expected to occur here, it seems safer to special-case
                     * it here and keep the assertions that ROWID_VARs
                     * shouldn't be seen by fix_scan_expr.
                     *
                     * We also must handle the case where set operations have
                     * been short-circuited resulting in a dummy Result node.
                     * prepunion.c uses varno==0 for the set op targetlist.
                     * See generate_setop_tlist() and generate_setop_tlist().
                     * Here we rewrite these to use varno==1, which is the
                     * varno of the first set-op child.  Without this, EXPLAIN
                     * will have trouble displaying targetlists of dummy set
                     * operations.
                     */
                    foreach(l, splan->plan.targetlist)
                    {
                        TargetEntry *tle = (TargetEntry *) lfirst(l);
                        Var        *var = (Var *) tle->expr;
 
                        if (var && IsA(var, Var))
                        {
                            if (var->varno == ROWID_VAR)
                                tle->expr = (Expr *) makeNullConst(var->vartype,
                                                                   var->vartypmod,
                                                                   var->varcollid);
                            else if (var->varno == 0)
                                tle->expr = (Expr *) makeVar(1,
                                                             var->varattno,
                                                             var->vartype,
                                                             var->vartypmod,
                                                             var->varcollid,
                                                             var->varlevelsup);
                        }
                    }
 
                    splan->plan.targetlist =
                        fix_scan_list(root, splan->plan.targetlist,
                                      rtoffset, NUM_EXEC_TLIST(plan));
                    splan->plan.qual =
                        fix_scan_list(root, splan->plan.qual,
                                      rtoffset, NUM_EXEC_QUAL(plan));
                }
                /* resconstantqual can't contain any subplan variable refs */
                splan->resconstantqual =
                    fix_scan_expr(root, splan->resconstantqual, rtoffset, 1);
                /* adjust the relids set */
                splan->relids = offset_relid_set(splan->relids, rtoffset);
            }
            break;
        case T_ProjectSet:
            set_upper_references(root, plan, rtoffset);
            break;
        case T_ModifyTable:
            {
                ModifyTable *splan = (ModifyTable *) plan;
                Plan       *subplan = outerPlan(splan);
 
                Assert(splan->plan.targetlist == NIL);
                Assert(splan->plan.qual == NIL);
 
                splan->withCheckOptionLists =
                    fix_scan_list(root, splan->withCheckOptionLists,
                                  rtoffset, 1);
 
                if (splan->returningLists)
                {
                    List       *newRL = NIL;
                    ListCell   *lcrl,
                               *lcrr;
 
                    /*
                     * Pass each per-resultrel returningList through
                     * set_returning_clause_references().
                     */
                    Assert(list_length(splan->returningLists) == list_length(splan->resultRelations));
                    forboth(lcrl, splan->returningLists,
                            lcrr, splan->resultRelations)
                    {
                        List       *rlist = (List *) lfirst(lcrl);
                        Index       resultrel = lfirst_int(lcrr);
 
                        rlist = set_returning_clause_references(root,
                                                                rlist,
                                                                subplan,
                                                                resultrel,
                                                                rtoffset);
                        newRL = lappend(newRL, rlist);
                    }
                    splan->returningLists = newRL;
 
                    /*
                     * Set up the visible plan targetlist as being the same as
                     * the first RETURNING list.  This is mostly for the use
                     * of EXPLAIN; the executor won't execute that targetlist,
                     * although it does use it to prepare the node's result
                     * tuple slot.  We postpone this step until here so that
                     * we don't have to do set_returning_clause_references()
                     * twice on identical targetlists.
                     */
                    splan->plan.targetlist = copyObject(linitial(newRL));
                }
 
                /*
                 * We treat ModifyTable with ON CONFLICT as a form of 'pseudo
                 * join', where the inner side is the EXCLUDED tuple.
                 * Therefore use fix_join_expr to setup the relevant variables
                 * to INNER_VAR. We explicitly don't create any OUTER_VARs as
                 * those are already used by RETURNING and it seems better to
                 * be non-conflicting.
                 */
                if (splan->onConflictSet)
                {
                    indexed_tlist *itlist;
 
                    itlist = build_tlist_index(splan->exclRelTlist);
 
                    splan->onConflictSet =
                        fix_join_expr(root, splan->onConflictSet,
                                      NULL, itlist,
                                      linitial_int(splan->resultRelations),
                                      rtoffset, NRM_EQUAL, NUM_EXEC_QUAL(plan));
 
                    splan->onConflictWhere = (Node *)
                        fix_join_expr(root, (List *) splan->onConflictWhere,
                                      NULL, itlist,
                                      linitial_int(splan->resultRelations),
                                      rtoffset, NRM_EQUAL, NUM_EXEC_QUAL(plan));
 
                    pfree(itlist);
 
                    splan->exclRelTlist =
                        fix_scan_list(root, splan->exclRelTlist, rtoffset, 1);
                }
 
                /*
                 * The MERGE statement produces the target rows by performing
                 * a right join between the target relation and the source
                 * relation (which could be a plain relation or a subquery).
                 * The INSERT and UPDATE actions of the MERGE statement
                 * require access to the columns from the source relation. We
                 * arrange things so that the source relation attributes are
                 * available as INNER_VAR and the target relation attributes
                 * are available from the scan tuple.
                 */
                if (splan->mergeActionLists != NIL)
                {
                    List       *newMJC = NIL;
                    ListCell   *lca,
                               *lcj,
                               *lcr;
 
                    /*
                     * Fix the targetList of individual action nodes so that
                     * the so-called "source relation" Vars are referenced as
                     * INNER_VAR.  Note that for this to work correctly during
                     * execution, the ecxt_innertuple must be set to the tuple
                     * obtained by executing the subplan, which is what
                     * constitutes the "source relation".
                     *
                     * We leave the Vars from the result relation (i.e. the
                     * target relation) unchanged i.e. those Vars would be
                     * picked from the scan slot. So during execution, we must
                     * ensure that ecxt_scantuple is setup correctly to refer
                     * to the tuple from the target relation.
                     */
                    indexed_tlist *itlist;
 
                    itlist = build_tlist_index(subplan->targetlist);
 
                    forthree(lca, splan->mergeActionLists,
                             lcj, splan->mergeJoinConditions,
                             lcr, splan->resultRelations)
                    {
                        List       *mergeActionList = lfirst(lca);
                        Node       *mergeJoinCondition = lfirst(lcj);
                        Index       resultrel = lfirst_int(lcr);
 
                        foreach(l, mergeActionList)
                        {
                            MergeAction *action = (MergeAction *) lfirst(l);
 
                            /* Fix targetList of each action. */
                            action->targetList = fix_join_expr(root,
                                                               action->targetList,
                                                               NULL, itlist,
                                                               resultrel,
                                                               rtoffset,
                                                               NRM_EQUAL,
                                                               NUM_EXEC_TLIST(plan));
 
                            /* Fix quals too. */
                            action->qual = (Node *) fix_join_expr(root,
                                                                  (List *) action->qual,
                                                                  NULL, itlist,
                                                                  resultrel,
                                                                  rtoffset,
                                                                  NRM_EQUAL,
                                                                  NUM_EXEC_QUAL(plan));
                        }
 
                        /* Fix join condition too. */
                        mergeJoinCondition = (Node *)
                            fix_join_expr(root,
                                          (List *) mergeJoinCondition,
                                          NULL, itlist,
                                          resultrel,
                                          rtoffset,
                                          NRM_EQUAL,
                                          NUM_EXEC_QUAL(plan));
                        newMJC = lappend(newMJC, mergeJoinCondition);
                    }
                    splan->mergeJoinConditions = newMJC;
                }
 
                splan->nominalRelation += rtoffset;
                if (splan->rootRelation)
                    splan->rootRelation += rtoffset;
                splan->exclRelRTI += rtoffset;
 
                foreach(l, splan->resultRelations)
                {
                    lfirst_int(l) += rtoffset;
                }
                foreach(l, splan->rowMarks)
                {
                    PlanRowMark *rc = (PlanRowMark *) lfirst(l);
 
                    rc->rti += rtoffset;
                    rc->prti += rtoffset;
                }
 
                /*
                 * Append this ModifyTable node's final result relation RT
                 * index(es) to the global list for the plan.
                 */
                root->glob->resultRelations =
                    list_concat(root->glob->resultRelations,
                                splan->resultRelations);
                if (splan->rootRelation)
                {
                    root->glob->resultRelations =
                        lappend_int(root->glob->resultRelations,
                                    splan->rootRelation);
                }
            }
            break;
        case T_Append:
            /* Needs special treatment, see comments below */
            return set_append_references(root,
                                         (Append *) plan,
                                         rtoffset);
        case T_MergeAppend:
            /* Needs special treatment, see comments below */
            return set_mergeappend_references(root,
                                              (MergeAppend *) plan,
                                              rtoffset);
        case T_RecursiveUnion:
            /* This doesn't evaluate targetlist or check quals either */
            set_dummy_tlist_references(plan, rtoffset);
            Assert(plan->qual == NIL);
            break;
        case T_BitmapAnd:
            {
                BitmapAnd  *splan = (BitmapAnd *) plan;
 
                /* BitmapAnd works like Append, but has no tlist */
                Assert(splan->plan.targetlist == NIL);
                Assert(splan->plan.qual == NIL);
                foreach(l, splan->bitmapplans)
                {
                    lfirst(l) = set_plan_refs(root,
                                              (Plan *) lfirst(l),
                                              rtoffset);
                }
            }
            break;
        case T_BitmapOr:
            {
                BitmapOr   *splan = (BitmapOr *) plan;
 
                /* BitmapOr works like Append, but has no tlist */
                Assert(splan->plan.targetlist == NIL);
                Assert(splan->plan.qual == NIL);
                foreach(l, splan->bitmapplans)
                {
                    lfirst(l) = set_plan_refs(root,
                                              (Plan *) lfirst(l),
                                              rtoffset);
                }
            }
            break;
        default:
            elog(ERROR, "unrecognized node type: %d",
                 (int) nodeTag(plan));
            break;
    }
 
    /*
     * Now recurse into child plans, if any
     *
     * NOTE: it is essential that we recurse into child plans AFTER we set
     * subplan references in this plan's tlist and quals.  If we did the
     * reference-adjustments bottom-up, then we would fail to match this
     * plan's var nodes against the already-modified nodes of the children.
     */
    plan->lefttree = set_plan_refs(root, plan->lefttree, rtoffset);
    plan->righttree = set_plan_refs(root, plan->righttree, rtoffset);
 
    return plan;
}
 
/*
 * set_indexonlyscan_references
 *      Do set_plan_references processing on an IndexOnlyScan
 *
 * This is unlike the handling of a plain IndexScan because we have to
 * convert Vars referencing the heap into Vars referencing the index.
 * We can use the fix_upper_expr machinery for that, by working from a
 * targetlist describing the index columns.
 */
static Plan *
set_indexonlyscan_references(PlannerInfo *root,
                             IndexOnlyScan *plan,
                             int rtoffset)
{
    indexed_tlist *index_itlist;
    List       *stripped_indextlist;
    ListCell   *lc;
 
    /*
     * Vars in the plan node's targetlist, qual, and recheckqual must only
     * reference columns that the index AM can actually return.  To ensure
     * this, remove non-returnable columns (which are marked as resjunk) from
     * the indexed tlist.  We can just drop them because the indexed_tlist
     * machinery pays attention to TLE resnos, not physical list position.
     */
    stripped_indextlist = NIL;
    foreach(lc, plan->indextlist)
    {
        TargetEntry *indextle = (TargetEntry *) lfirst(lc);
 
        if (!indextle->resjunk)
            stripped_indextlist = lappend(stripped_indextlist, indextle);
    }
 
    index_itlist = build_tlist_index(stripped_indextlist);
 
    plan->scan.scanrelid += rtoffset;
    plan->scan.plan.targetlist = (List *)
        fix_upper_expr(root,
                       (Node *) plan->scan.plan.targetlist,
                       index_itlist,
                       INDEX_VAR,
                       rtoffset,
                       NRM_EQUAL,
                       NUM_EXEC_TLIST((Plan *) plan));
    plan->scan.plan.qual = (List *)
        fix_upper_expr(root,
                       (Node *) plan->scan.plan.qual,
                       index_itlist,
                       INDEX_VAR,
                       rtoffset,
                       NRM_EQUAL,
                       NUM_EXEC_QUAL((Plan *) plan));
    plan->recheckqual = (List *)
        fix_upper_expr(root,
                       (Node *) plan->recheckqual,
                       index_itlist,
                       INDEX_VAR,
                       rtoffset,
                       NRM_EQUAL,
                       NUM_EXEC_QUAL((Plan *) plan));
    /* indexqual is already transformed to reference index columns */
    plan->indexqual = fix_scan_list(root, plan->indexqual,
                                    rtoffset, 1);
    /* indexorderby is already transformed to reference index columns */
    plan->indexorderby = fix_scan_list(root, plan->indexorderby,
                                       rtoffset, 1);
    /* indextlist must NOT be transformed to reference index columns */
    plan->indextlist = fix_scan_list(root, plan->indextlist,
                                     rtoffset, NUM_EXEC_TLIST((Plan *) plan));
 
    pfree(index_itlist);
 
    return (Plan *) plan;
}
 
/*
 * set_subqueryscan_references
 *      Do set_plan_references processing on a SubqueryScan
 *
 * We try to strip out the SubqueryScan entirely; if we can't, we have
 * to do the normal processing on it.
 */
static Plan *
set_subqueryscan_references(PlannerInfo *root,
                            SubqueryScan *plan,
                            int rtoffset)
{
    RelOptInfo *rel;
    Plan       *result;
 
    /* Need to look up the subquery's RelOptInfo, since we need its subroot */
    rel = find_base_rel(root, plan->scan.scanrelid);
 
    /* Recursively process the subplan */
    plan->subplan = set_plan_references(rel->subroot, plan->subplan);
 
    if (trivial_subqueryscan(plan))
    {
        /*
         * We can omit the SubqueryScan node and just pull up the subplan.
         */
        result = clean_up_removed_plan_level((Plan *) plan, plan->subplan);
    }
    else
    {
        /*
         * Keep the SubqueryScan node.  We have to do the processing that
         * set_plan_references would otherwise have done on it.  Notice we do
         * not do set_upper_references() here, because a SubqueryScan will
         * always have been created with correct references to its subplan's
         * outputs to begin with.
         */
        plan->scan.scanrelid += rtoffset;
        plan->scan.plan.targetlist =
            fix_scan_list(root, plan->scan.plan.targetlist,
                          rtoffset, NUM_EXEC_TLIST((Plan *) plan));
        plan->scan.plan.qual =
            fix_scan_list(root, plan->scan.plan.qual,
                          rtoffset, NUM_EXEC_QUAL((Plan *) plan));
 
        result = (Plan *) plan;
    }
 
    return result;
}
 
/*
 * trivial_subqueryscan
 *      Detect whether a SubqueryScan can be deleted from the plan tree.
 *
 * We can delete it if it has no qual to check and the targetlist just
 * regurgitates the output of the child plan.
 *
 * This can be called from mark_async_capable_plan(), a helper function for
 * create_append_plan(), before set_subqueryscan_references(), to determine
 * triviality of a SubqueryScan that is a child of an Append node.  So we
 * cache the result in the SubqueryScan node to avoid repeated computation.
 *
 * Note: when called from mark_async_capable_plan(), we determine the result
 * before running finalize_plan() on the SubqueryScan node (if needed) and
 * set_plan_references() on the subplan tree, but this would be safe, because
 * 1) finalize_plan() doesn't modify the tlist or quals for the SubqueryScan
 *    node (or that for any plan node in the subplan tree), and
 * 2) set_plan_references() modifies the tlist for every plan node in the
 *    subplan tree, but keeps const/resjunk columns as const/resjunk ones and
 *    preserves the length and order of the tlist, and
 * 3) set_plan_references() might delete the topmost plan node like an Append
 *    or MergeAppend from the subplan tree and pull up the child plan node,
 *    but in that case, the tlist for the child plan node exactly matches the
 *    parent.
 */
bool
trivial_subqueryscan(SubqueryScan *plan)
{
    int         attrno;
    ListCell   *lp,
               *lc;
 
    /* We might have detected this already; in which case reuse the result */
    if (plan->scanstatus == SUBQUERY_SCAN_TRIVIAL)
        return true;
    if (plan->scanstatus == SUBQUERY_SCAN_NONTRIVIAL)
        return false;
    Assert(plan->scanstatus == SUBQUERY_SCAN_UNKNOWN);
    /* Initially, mark the SubqueryScan as non-deletable from the plan tree */
    plan->scanstatus = SUBQUERY_SCAN_NONTRIVIAL;
 
    if (plan->scan.plan.qual != NIL)
        return false;
 
    if (list_length(plan->scan.plan.targetlist) !=
        list_length(plan->subplan->targetlist))
        return false;           /* tlists not same length */
 
    attrno = 1;
    forboth(lp, plan->scan.plan.targetlist, lc, plan->subplan->targetlist)
    {
        TargetEntry *ptle = (TargetEntry *) lfirst(lp);
        TargetEntry *ctle = (TargetEntry *) lfirst(lc);
 
        if (ptle->resjunk != ctle->resjunk)
            return false;       /* tlist doesn't match junk status */
 
        /*
         * We accept either a Var referencing the corresponding element of the
         * subplan tlist, or a Const equaling the subplan element. See
         * generate_setop_tlist() for motivation.
         */
        if (ptle->expr && IsA(ptle->expr, Var))
        {
            Var        *var = (Var *) ptle->expr;
 
            Assert(var->varno == plan->scan.scanrelid);
            Assert(var->varlevelsup == 0);
            if (var->varattno != attrno)
                return false;   /* out of order */
        }
        else if (ptle->expr && IsA(ptle->expr, Const))
        {
            if (!equal(ptle->expr, ctle->expr))
                return false;
        }
        else
            return false;
 
        attrno++;
    }
 
    /* Re-mark the SubqueryScan as deletable from the plan tree */
    plan->scanstatus = SUBQUERY_SCAN_TRIVIAL;
 
    return true;
}
 
/*
 * clean_up_removed_plan_level
 *      Do necessary cleanup when we strip out a SubqueryScan, Append, etc
 *
 * We are dropping the "parent" plan in favor of returning just its "child".
 * A few small tweaks are needed.
 */
static Plan *
clean_up_removed_plan_level(Plan *parent, Plan *child)
{
    /*
     * We have to be sure we don't lose any initplans, so move any that were
     * attached to the parent plan to the child.  If any are parallel-unsafe,
     * the child is no longer parallel-safe.  As a cosmetic matter, also add
     * the initplans' run costs to the child's costs.
     */
    if (parent->initPlan)
    {
        Cost        initplan_cost;
        bool        unsafe_initplans;
 
        SS_compute_initplan_cost(parent->initPlan,
                                 &initplan_cost, &unsafe_initplans);
        child->startup_cost += initplan_cost;
        child->total_cost += initplan_cost;
        if (unsafe_initplans)
            child->parallel_safe = false;
 
        /*
         * Attach plans this way so that parent's initplans are processed
         * before any pre-existing initplans of the child.  Probably doesn't
         * matter, but let's preserve the ordering just in case.
         */
        child->initPlan = list_concat(parent->initPlan,
                                      child->initPlan);
    }
 
    /*
     * We also have to transfer the parent's column labeling info into the
     * child, else columns sent to client will be improperly labeled if this
     * is the topmost plan level.  resjunk and so on may be important too.
     */
    apply_tlist_labeling(child->targetlist, parent->targetlist);
 
    return child;
}
 
/*
 * set_foreignscan_references
 *     Do set_plan_references processing on a ForeignScan
 */
static void
set_foreignscan_references(PlannerInfo *root,
                           ForeignScan *fscan,
                           int rtoffset)
{
    /* Adjust scanrelid if it's valid */
    if (fscan->scan.scanrelid > 0)
        fscan->scan.scanrelid += rtoffset;
 
    if (fscan->fdw_scan_tlist != NIL || fscan->scan.scanrelid == 0)
    {
        /*
         * Adjust tlist, qual, fdw_exprs, fdw_recheck_quals to reference
         * foreign scan tuple
         */
        indexed_tlist *itlist = build_tlist_index(fscan->fdw_scan_tlist);
 
        fscan->scan.plan.targetlist = (List *)
            fix_upper_expr(root,
                           (Node *) fscan->scan.plan.targetlist,
                           itlist,
                           INDEX_VAR,
                           rtoffset,
                           NRM_EQUAL,
                           NUM_EXEC_TLIST((Plan *) fscan));
        fscan->scan.plan.qual = (List *)
            fix_upper_expr(root,
                           (Node *) fscan->scan.plan.qual,
                           itlist,
                           INDEX_VAR,
                           rtoffset,
                           NRM_EQUAL,
                           NUM_EXEC_QUAL((Plan *) fscan));
        fscan->fdw_exprs = (List *)
            fix_upper_expr(root,
                           (Node *) fscan->fdw_exprs,
                           itlist,
                           INDEX_VAR,
                           rtoffset,
                           NRM_EQUAL,
                           NUM_EXEC_QUAL((Plan *) fscan));
        fscan->fdw_recheck_quals = (List *)
            fix_upper_expr(root,
                           (Node *) fscan->fdw_recheck_quals,
                           itlist,
                           INDEX_VAR,
                           rtoffset,
                           NRM_EQUAL,
                           NUM_EXEC_QUAL((Plan *) fscan));
        pfree(itlist);
        /* fdw_scan_tlist itself just needs fix_scan_list() adjustments */
        fscan->fdw_scan_tlist =
            fix_scan_list(root, fscan->fdw_scan_tlist,
                          rtoffset, NUM_EXEC_TLIST((Plan *) fscan));
    }
    else
    {
        /*
         * Adjust tlist, qual, fdw_exprs, fdw_recheck_quals in the standard
         * way
         */
        fscan->scan.plan.targetlist =
            fix_scan_list(root, fscan->scan.plan.targetlist,
                          rtoffset, NUM_EXEC_TLIST((Plan *) fscan));
        fscan->scan.plan.qual =
            fix_scan_list(root, fscan->scan.plan.qual,
                          rtoffset, NUM_EXEC_QUAL((Plan *) fscan));
        fscan->fdw_exprs =
            fix_scan_list(root, fscan->fdw_exprs,
                          rtoffset, NUM_EXEC_QUAL((Plan *) fscan));
        fscan->fdw_recheck_quals =
            fix_scan_list(root, fscan->fdw_recheck_quals,
                          rtoffset, NUM_EXEC_QUAL((Plan *) fscan));
    }
 
    fscan->fs_relids = offset_relid_set(fscan->fs_relids, rtoffset);
    fscan->fs_base_relids = offset_relid_set(fscan->fs_base_relids, rtoffset);
 
    /* Adjust resultRelation if it's valid */
    if (fscan->resultRelation > 0)
        fscan->resultRelation += rtoffset;
}
 
/*
 * set_customscan_references
 *     Do set_plan_references processing on a CustomScan
 */
static void
set_customscan_references(PlannerInfo *root,
                          CustomScan *cscan,
                          int rtoffset)
{
    ListCell   *lc;
 
    /* Adjust scanrelid if it's valid */
    if (cscan->scan.scanrelid > 0)
        cscan->scan.scanrelid += rtoffset;
 
    if (cscan->custom_scan_tlist != NIL || cscan->scan.scanrelid == 0)
    {
        /* Adjust tlist, qual, custom_exprs to reference custom scan tuple */
        indexed_tlist *itlist = build_tlist_index(cscan->custom_scan_tlist);
 
        cscan->scan.plan.targetlist = (List *)
            fix_upper_expr(root,
                           (Node *) cscan->scan.plan.targetlist,
                           itlist,
                           INDEX_VAR,
                           rtoffset,
                           NRM_EQUAL,
                           NUM_EXEC_TLIST((Plan *) cscan));
        cscan->scan.plan.qual = (List *)
            fix_upper_expr(root,
                           (Node *) cscan->scan.plan.qual,
                           itlist,
                           INDEX_VAR,
                           rtoffset,
                           NRM_EQUAL,
                           NUM_EXEC_QUAL((Plan *) cscan));
        cscan->custom_exprs = (List *)
            fix_upper_expr(root,
                           (Node *) cscan->custom_exprs,
                           itlist,
                           INDEX_VAR,
                           rtoffset,
                           NRM_EQUAL,
                           NUM_EXEC_QUAL((Plan *) cscan));
        pfree(itlist);
        /* custom_scan_tlist itself just needs fix_scan_list() adjustments */
        cscan->custom_scan_tlist =
            fix_scan_list(root, cscan->custom_scan_tlist,
                          rtoffset, NUM_EXEC_TLIST((Plan *) cscan));
    }
    else
    {
        /* Adjust tlist, qual, custom_exprs in the standard way */
        cscan->scan.plan.targetlist =
            fix_scan_list(root, cscan->scan.plan.targetlist,
                          rtoffset, NUM_EXEC_TLIST((Plan *) cscan));
        cscan->scan.plan.qual =
            fix_scan_list(root, cscan->scan.plan.qual,
                          rtoffset, NUM_EXEC_QUAL((Plan *) cscan));
        cscan->custom_exprs =
            fix_scan_list(root, cscan->custom_exprs,
                          rtoffset, NUM_EXEC_QUAL((Plan *) cscan));
    }
 
    /* Adjust child plan-nodes recursively, if needed */
    foreach(lc, cscan->custom_plans)
    {
        lfirst(lc) = set_plan_refs(root, (Plan *) lfirst(lc), rtoffset);
    }
 
    cscan->custom_relids = offset_relid_set(cscan->custom_relids, rtoffset);
}
 
/*
 * register_partpruneinfo
 *      Subroutine for set_append_references and set_mergeappend_references
 *
 * Add the PartitionPruneInfo from root->partPruneInfos at the given index
 * into PlannerGlobal->partPruneInfos and return its index there.
 *
 * Also update the RT indexes present in PartitionedRelPruneInfos to add the
 * offset.
 *
 * Finally, if there are initial pruning steps, add the RT indexes of the
 * leaf partitions to the set of relations that are prunable at execution
 * startup time.
 */
static int
register_partpruneinfo(PlannerInfo *root, int part_prune_index, int rtoffset)
{
    PlannerGlobal *glob = root->glob;
    PartitionPruneInfo *pinfo;
    ListCell   *l;
 
    Assert(part_prune_index >= 0 &&
           part_prune_index < list_length(root->partPruneInfos));
    pinfo = list_nth_node(PartitionPruneInfo, root->partPruneInfos,
                          part_prune_index);
 
    pinfo->relids = offset_relid_set(pinfo->relids, rtoffset);
    foreach(l, pinfo->prune_infos)
    {
        List       *prune_infos = lfirst(l);
        ListCell   *l2;
 
        foreach(l2, prune_infos)
        {
            PartitionedRelPruneInfo *prelinfo = lfirst(l2);
            int         i;
 
            prelinfo->rtindex += rtoffset;
            prelinfo->initial_pruning_steps =
                fix_scan_list(root, prelinfo->initial_pruning_steps,
                              rtoffset, 1);
            prelinfo->exec_pruning_steps =
                fix_scan_list(root, prelinfo->exec_pruning_steps,
                              rtoffset, 1);
 
            for (i = 0; i < prelinfo->nparts; i++)
            {
                /*
                 * Non-leaf partitions and partitions that do not have a
                 * subplan are not included in this map as mentioned in
                 * make_partitionedrel_pruneinfo().
                 */
                if (prelinfo->leafpart_rti_map[i])
                {
                    prelinfo->leafpart_rti_map[i] += rtoffset;
                    if (prelinfo->initial_pruning_steps)
                        glob->prunableRelids = bms_add_member(glob->prunableRelids,
                                                              prelinfo->leafpart_rti_map[i]);
                }
            }
        }
    }
 
    glob->partPruneInfos = lappend(glob->partPruneInfos, pinfo);
 
    return list_length(glob->partPruneInfos) - 1;
}
 
/*
 * set_append_references
 *      Do set_plan_references processing on an Append
 *
 * We try to strip out the Append entirely; if we can't, we have
 * to do the normal processing on it.
 */
static Plan *
set_append_references(PlannerInfo *root,
                      Append *aplan,
                      int rtoffset)
{
    ListCell   *l;
 
    /*
     * Append, like Sort et al, doesn't actually evaluate its targetlist or
     * check quals.  If it's got exactly one child plan, then it's not doing
     * anything useful at all, and we can strip it out.
     */
    Assert(aplan->plan.qual == NIL);
 
    /* First, we gotta recurse on the children */
    foreach(l, aplan->appendplans)
    {
        lfirst(l) = set_plan_refs(root, (Plan *) lfirst(l), rtoffset);
    }
 
    /*
     * See if it's safe to get rid of the Append entirely.  For this to be
     * safe, there must be only one child plan and that child plan's parallel
     * awareness must match the Append's.  The reason for the latter is that
     * if the Append is parallel aware and the child is not, then the calling
     * plan may execute the non-parallel aware child multiple times.  (If you
     * change these rules, update create_append_path to match.)
     */
    if (list_length(aplan->appendplans) == 1)
    {
        Plan       *p = (Plan *) linitial(aplan->appendplans);
 
        if (p->parallel_aware == aplan->plan.parallel_aware)
            return clean_up_removed_plan_level((Plan *) aplan, p);
    }
 
    /*
     * Otherwise, clean up the Append as needed.  It's okay to do this after
     * recursing to the children, because set_dummy_tlist_references doesn't
     * look at those.
     */
    set_dummy_tlist_references((Plan *) aplan, rtoffset);
 
    aplan->apprelids = offset_relid_set(aplan->apprelids, rtoffset);
 
    /*
     * Add PartitionPruneInfo, if any, to PlannerGlobal and update the index.
     * Also update the RT indexes present in it to add the offset.
     */
    if (aplan->part_prune_index >= 0)
        aplan->part_prune_index =
            register_partpruneinfo(root, aplan->part_prune_index, rtoffset);
 
    /* We don't need to recurse to lefttree or righttree ... */
    Assert(aplan->plan.lefttree == NULL);
    Assert(aplan->plan.righttree == NULL);
 
    return (Plan *) aplan;
}
 
/*
 * set_mergeappend_references
 *      Do set_plan_references processing on a MergeAppend
 *
 * We try to strip out the MergeAppend entirely; if we can't, we have
 * to do the normal processing on it.
 */
static Plan *
set_mergeappend_references(PlannerInfo *root,
                           MergeAppend *mplan,
                           int rtoffset)
{
    ListCell   *l;
 
    /*
     * MergeAppend, like Sort et al, doesn't actually evaluate its targetlist
     * or check quals.  If it's got exactly one child plan, then it's not
     * doing anything useful at all, and we can strip it out.
     */
    Assert(mplan->plan.qual == NIL);
 
    /* First, we gotta recurse on the children */
    foreach(l, mplan->mergeplans)
    {
        lfirst(l) = set_plan_refs(root, (Plan *) lfirst(l), rtoffset);
    }
 
    /*
     * See if it's safe to get rid of the MergeAppend entirely.  For this to
     * be safe, there must be only one child plan and that child plan's
     * parallel awareness must match the MergeAppend's.  The reason for the
     * latter is that if the MergeAppend is parallel aware and the child is
     * not, then the calling plan may execute the non-parallel aware child
     * multiple times.  (If you change these rules, update
     * create_merge_append_path to match.)
     */
    if (list_length(mplan->mergeplans) == 1)
    {
        Plan       *p = (Plan *) linitial(mplan->mergeplans);
 
        if (p->parallel_aware == mplan->plan.parallel_aware)
            return clean_up_removed_plan_level((Plan *) mplan, p);
    }
 
    /*
     * Otherwise, clean up the MergeAppend as needed.  It's okay to do this
     * after recursing to the children, because set_dummy_tlist_references
     * doesn't look at those.
     */
    set_dummy_tlist_references((Plan *) mplan, rtoffset);
 
    mplan->apprelids = offset_relid_set(mplan->apprelids, rtoffset);
 
    /*
     * Add PartitionPruneInfo, if any, to PlannerGlobal and update the index.
     * Also update the RT indexes present in it to add the offset.
     */
    if (mplan->part_prune_index >= 0)
        mplan->part_prune_index =
            register_partpruneinfo(root, mplan->part_prune_index, rtoffset);
 
    /* We don't need to recurse to lefttree or righttree ... */
    Assert(mplan->plan.lefttree == NULL);
    Assert(mplan->plan.righttree == NULL);
 
    return (Plan *) mplan;
}
 
/*
 * set_hash_references
 *     Do set_plan_references processing on a Hash node
 */
static void
set_hash_references(PlannerInfo *root, Plan *plan, int rtoffset)
{
    Hash       *hplan = (Hash *) plan;
    Plan       *outer_plan = plan->lefttree;
    indexed_tlist *outer_itlist;
 
    /*
     * Hash's hashkeys are used when feeding tuples into the hashtable,
     * therefore have them reference Hash's outer plan (which itself is the
     * inner plan of the HashJoin).
     */
    outer_itlist = build_tlist_index(outer_plan->targetlist);
    hplan->hashkeys = (List *)
        fix_upper_expr(root,
                       (Node *) hplan->hashkeys,
                       outer_itlist,
                       OUTER_VAR,
                       rtoffset,
                       NRM_EQUAL,
                       NUM_EXEC_QUAL(plan));
 
    /* Hash doesn't project */
    set_dummy_tlist_references(plan, rtoffset);
 
    /* Hash nodes don't have their own quals */
    Assert(plan->qual == NIL);
}
 
/*
 * offset_relid_set
 *      Apply rtoffset to the members of a Relids set.
 */
static Relids
offset_relid_set(Relids relids, int rtoffset)
{
    Relids      result = NULL;
    int         rtindex;
 
    /* If there's no offset to apply, we needn't recompute the value */
    if (rtoffset == 0)
        return relids;
    rtindex = -1;
    while ((rtindex = bms_next_member(relids, rtindex)) >= 0)
        result = bms_add_member(result, rtindex + rtoffset);
    return result;
}
 
/*
 * copyVar
 *      Copy a Var node.
 *
 * fix_scan_expr and friends do this enough times that it's worth having
 * a bespoke routine instead of using the generic copyObject() function.
 */
static inline Var *
copyVar(Var *var)
{
    Var        *newvar = (Var *) palloc(sizeof(Var));
 
    *newvar = *var;
    return newvar;
}
 
/*
 * fix_expr_common
 *      Do generic set_plan_references processing on an expression node
 *
 * This is code that is common to all variants of expression-fixing.
 * We must look up operator opcode info for OpExpr and related nodes,
 * add OIDs from regclass Const nodes into root->glob->relationOids, and
 * add PlanInvalItems for user-defined functions into root->glob->invalItems.
 * We also fill in column index lists for GROUPING() expressions.
 *
 * We assume it's okay to update opcode info in-place.  So this could possibly
 * scribble on the planner's input data structures, but it's OK.
 */
static void
fix_expr_common(PlannerInfo *root, Node *node)
{
    /* We assume callers won't call us on a NULL pointer */
    if (IsA(node, Aggref))
    {
        record_plan_function_dependency(root,
                                        ((Aggref *) node)->aggfnoid);
    }
    else if (IsA(node, WindowFunc))
    {
        record_plan_function_dependency(root,
                                        ((WindowFunc *) node)->winfnoid);
    }
    else if (IsA(node, FuncExpr))
    {
        record_plan_function_dependency(root,
                                        ((FuncExpr *) node)->funcid);
    }
    else if (IsA(node, OpExpr))
    {
        set_opfuncid((OpExpr *) node);
        record_plan_function_dependency(root,
                                        ((OpExpr *) node)->opfuncid);
    }
    else if (IsA(node, DistinctExpr))
    {
        set_opfuncid((OpExpr *) node);  /* rely on struct equivalence */
        record_plan_function_dependency(root,
                                        ((DistinctExpr *) node)->opfuncid);
    }
    else if (IsA(node, NullIfExpr))
    {
        set_opfuncid((OpExpr *) node);  /* rely on struct equivalence */
        record_plan_function_dependency(root,
                                        ((NullIfExpr *) node)->opfuncid);
    }
    else if (IsA(node, ScalarArrayOpExpr))
    {
        ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) node;
 
        set_sa_opfuncid(saop);
        record_plan_function_dependency(root, saop->opfuncid);
 
        if (OidIsValid(saop->hashfuncid))
            record_plan_function_dependency(root, saop->hashfuncid);
 
        if (OidIsValid(saop->negfuncid))
            record_plan_function_dependency(root, saop->negfuncid);
    }
    else if (IsA(node, Const))
    {
        Const      *con = (Const *) node;
 
        /* Check for regclass reference */
        if (ISREGCLASSCONST(con))
            root->glob->relationOids =
                lappend_oid(root->glob->relationOids,
                            DatumGetObjectId(con->constvalue));
    }
    else if (IsA(node, GroupingFunc))
    {
        GroupingFunc *g = (GroupingFunc *) node;
        AttrNumber *grouping_map = root->grouping_map;
 
        /* If there are no grouping sets, we don't need this. */
 
        Assert(grouping_map || g->cols == NIL);
 
        if (grouping_map)
        {
            ListCell   *lc;
            List       *cols = NIL;
 
            foreach(lc, g->refs)
            {
                cols = lappend_int(cols, grouping_map[lfirst_int(lc)]);
            }
 
            Assert(!g->cols || equal(cols, g->cols));
 
            if (!g->cols)
                g->cols = cols;
        }
    }
}
 
/*
 * fix_param_node
 *      Do set_plan_references processing on a Param
 *
 * If it's a PARAM_MULTIEXPR, replace it with the appropriate Param from
 * root->multiexpr_params; otherwise no change is needed.
 * Just for paranoia's sake, we make a copy of the node in either case.
 */
static Node *
fix_param_node(PlannerInfo *root, Param *p)
{
    if (p->paramkind == PARAM_MULTIEXPR)
    {
        int         subqueryid = p->paramid >> 16;
        int         colno = p->paramid & 0xFFFF;
        List       *params;
 
        if (subqueryid <= 0 ||
            subqueryid > list_length(root->multiexpr_params))
            elog(ERROR, "unexpected PARAM_MULTIEXPR ID: %d", p->paramid);
        params = (List *) list_nth(root->multiexpr_params, subqueryid - 1);
        if (colno <= 0 || colno > list_length(params))
            elog(ERROR, "unexpected PARAM_MULTIEXPR ID: %d", p->paramid);
        return copyObject(list_nth(params, colno - 1));
    }
    return (Node *) copyObject(p);
}
 
/*
 * fix_alternative_subplan
 *      Do set_plan_references processing on an AlternativeSubPlan
 *
 * Choose one of the alternative implementations and return just that one,
 * discarding the rest of the AlternativeSubPlan structure.
 * Note: caller must still recurse into the result!
 *
 * We don't make any attempt to fix up cost estimates in the parent plan
 * node or higher-level nodes.
 */
static Node *
fix_alternative_subplan(PlannerInfo *root, AlternativeSubPlan *asplan,
                        double num_exec)
{
    SubPlan    *bestplan = NULL;
    Cost        bestcost = 0;
    ListCell   *lc;
 
    /*
     * Compute the estimated cost of each subplan assuming num_exec
     * executions, and keep the cheapest one.  In event of exact equality of
     * estimates, we prefer the later plan; this is a bit arbitrary, but in
     * current usage it biases us to break ties against fast-start subplans.
     */
    Assert(asplan->subplans != NIL);
 
    foreach(lc, asplan->subplans)
    {
        SubPlan    *curplan = (SubPlan *) lfirst(lc);
        Cost        curcost;
 
        curcost = curplan->startup_cost + num_exec * curplan->per_call_cost;
        if (bestplan == NULL || curcost <= bestcost)
        {
            bestplan = curplan;
            bestcost = curcost;
        }
 
        /* Also mark all subplans that are in AlternativeSubPlans */
        root->isAltSubplan[curplan->plan_id - 1] = true;
    }
 
    /* Mark the subplan we selected */
    root->isUsedSubplan[bestplan->plan_id - 1] = true;
 
    return (Node *) bestplan;
}
 
/*
 * fix_scan_expr
 *      Do set_plan_references processing on a scan-level expression
 *
 * This consists of incrementing all Vars' varnos by rtoffset,
 * replacing PARAM_MULTIEXPR Params, expanding PlaceHolderVars,
 * replacing Aggref nodes that should be replaced by initplan output Params,
 * choosing the best implementation for AlternativeSubPlans,
 * looking up operator opcode info for OpExpr and related nodes,
 * and adding OIDs from regclass Const nodes into root->glob->relationOids.
 *
 * 'node': the expression to be modified
 * 'rtoffset': how much to increment varnos by
 * 'num_exec': estimated number of executions of expression
 *
 * The expression tree is either copied-and-modified, or modified in-place
 * if that seems safe.
 */
static Node *
fix_scan_expr(PlannerInfo *root, Node *node, int rtoffset, double num_exec)
{
    fix_scan_expr_context context;
 
    context.root = root;
    context.rtoffset = rtoffset;
    context.num_exec = num_exec;
 
    if (rtoffset != 0 ||
        root->multiexpr_params != NIL ||
        root->glob->lastPHId != 0 ||
        root->minmax_aggs != NIL ||
        root->hasAlternativeSubPlans)
    {
        return fix_scan_expr_mutator(node, &context);
    }
    else
    {
        /*
         * If rtoffset == 0, we don't need to change any Vars, and if there
         * are no MULTIEXPR subqueries then we don't need to replace
         * PARAM_MULTIEXPR Params, and if there are no placeholders anywhere
         * we won't need to remove them, and if there are no minmax Aggrefs we
         * won't need to replace them, and if there are no AlternativeSubPlans
         * we won't need to remove them.  Then it's OK to just scribble on the
         * input node tree instead of copying (since the only change, filling
         * in any unset opfuncid fields, is harmless).  This saves just enough
         * cycles to be noticeable on trivial queries.
         */
        (void) fix_scan_expr_walker(node, &context);
        return node;
    }
}
 
static Node *
fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context)
{
    if (node == NULL)
        return NULL;
    if (IsA(node, Var))
    {
        Var        *var = copyVar((Var *) node);
 
        Assert(var->varlevelsup == 0);
 
        /*
         * We should not see Vars marked INNER_VAR, OUTER_VAR, or ROWID_VAR.
         * But an indexqual expression could contain INDEX_VAR Vars.
         */
        Assert(var->varno != INNER_VAR);
        Assert(var->varno != OUTER_VAR);
        Assert(var->varno != ROWID_VAR);
        if (!IS_SPECIAL_VARNO(var->varno))
            var->varno += context->rtoffset;
        if (var->varnosyn > 0)
            var->varnosyn += context->rtoffset;
        return (Node *) var;
    }
    if (IsA(node, Param))
        return fix_param_node(context->root, (Param *) node);
    if (IsA(node, Aggref))
    {
        Aggref     *aggref = (Aggref *) node;
        Param      *aggparam;
 
        /* See if the Aggref should be replaced by a Param */
        aggparam = find_minmax_agg_replacement_param(context->root, aggref);
        if (aggparam != NULL)
        {
            /* Make a copy of the Param for paranoia's sake */
            return (Node *) copyObject(aggparam);
        }
        /* If no match, just fall through to process it normally */
    }
    if (IsA(node, CurrentOfExpr))
    {
        CurrentOfExpr *cexpr = (CurrentOfExpr *) copyObject(node);
 
        Assert(!IS_SPECIAL_VARNO(cexpr->cvarno));
        cexpr->cvarno += context->rtoffset;
        return (Node *) cexpr;
    }
    if (IsA(node, PlaceHolderVar))
    {
        /* At scan level, we should always just evaluate the contained expr */
        PlaceHolderVar *phv = (PlaceHolderVar *) node;
 
        /* XXX can we assert something about phnullingrels? */
        return fix_scan_expr_mutator((Node *) phv->phexpr, context);
    }
    if (IsA(node, AlternativeSubPlan))
        return fix_scan_expr_mutator(fix_alternative_subplan(context->root,
                                                             (AlternativeSubPlan *) node,
                                                             context->num_exec),
                                     context);
    fix_expr_common(context->root, node);
    return expression_tree_mutator(node, fix_scan_expr_mutator, context);
}
 
static bool
fix_scan_expr_walker(Node *node, fix_scan_expr_context *context)
{
    if (node == NULL)
        return false;
    Assert(!(IsA(node, Var) && ((Var *) node)->varno == ROWID_VAR));
    Assert(!IsA(node, PlaceHolderVar));
    Assert(!IsA(node, AlternativeSubPlan));
    fix_expr_common(context->root, node);
    return expression_tree_walker(node, fix_scan_expr_walker, context);
}
 
/*
 * set_join_references
 *    Modify the target list and quals of a join node to reference its
 *    subplans, by setting the varnos to OUTER_VAR or INNER_VAR and setting
 *    attno values to the result domain number of either the corresponding
 *    outer or inner join tuple item.  Also perform opcode lookup for these
 *    expressions, and add regclass OIDs to root->glob->relationOids.
 */
static void
set_join_references(PlannerInfo *root, Join *join, int rtoffset)
{
    Plan       *outer_plan = join->plan.lefttree;
    Plan       *inner_plan = join->plan.righttree;
    indexed_tlist *outer_itlist;
    indexed_tlist *inner_itlist;
 
    outer_itlist = build_tlist_index(outer_plan->targetlist);
    inner_itlist = build_tlist_index(inner_plan->targetlist);
 
    /*
     * First process the joinquals (including merge or hash clauses).  These
     * are logically below the join so they can always use all values
     * available from the input tlists.  It's okay to also handle
     * NestLoopParams now, because those couldn't refer to nullable
     * subexpressions.
     */
    join->joinqual = fix_join_expr(root,
                                   join->joinqual,
                                   outer_itlist,
                                   inner_itlist,
                                   (Index) 0,
                                   rtoffset,
                                   NRM_EQUAL,
                                   NUM_EXEC_QUAL((Plan *) join));
 
    /* Now do join-type-specific stuff */
    if (IsA(join, NestLoop))
    {
        NestLoop   *nl = (NestLoop *) join;
        ListCell   *lc;
 
        foreach(lc, nl->nestParams)
        {
            NestLoopParam *nlp = (NestLoopParam *) lfirst(lc);
 
            /*
             * Because we don't reparameterize parameterized paths to match
             * the outer-join level at which they are used, Vars seen in the
             * NestLoopParam expression may have nullingrels that are just a
             * subset of those in the Vars actually available from the outer
             * side.  (Lateral references can also cause this, as explained in
             * the comments for identify_current_nestloop_params.)  Not
             * checking this exactly is a bit grotty, but the work needed to
             * make things match up perfectly seems well out of proportion to
             * the value.
             */
            nlp->paramval = (Var *) fix_upper_expr(root,
                                                   (Node *) nlp->paramval,
                                                   outer_itlist,
                                                   OUTER_VAR,
                                                   rtoffset,
                                                   NRM_SUBSET,
                                                   NUM_EXEC_TLIST(outer_plan));
            /* Check we replaced any PlaceHolderVar with simple Var */
            if (!(IsA(nlp->paramval, Var) &&
                  nlp->paramval->varno == OUTER_VAR))
                elog(ERROR, "NestLoopParam was not reduced to a simple Var");
        }
    }
    else if (IsA(join, MergeJoin))
    {
        MergeJoin  *mj = (MergeJoin *) join;
 
        mj->mergeclauses = fix_join_expr(root,
                                         mj->mergeclauses,
                                         outer_itlist,
                                         inner_itlist,
                                         (Index) 0,
                                         rtoffset,
                                         NRM_EQUAL,
                                         NUM_EXEC_QUAL((Plan *) join));
    }
    else if (IsA(join, HashJoin))
    {
        HashJoin   *hj = (HashJoin *) join;
 
        hj->hashclauses = fix_join_expr(root,
                                        hj->hashclauses,
                                        outer_itlist,
                                        inner_itlist,
                                        (Index) 0,
                                        rtoffset,
                                        NRM_EQUAL,
                                        NUM_EXEC_QUAL((Plan *) join));
 
        /*
         * HashJoin's hashkeys are used to look for matching tuples from its
         * outer plan (not the Hash node!) in the hashtable.
         */
        hj->hashkeys = (List *) fix_upper_expr(root,
                                               (Node *) hj->hashkeys,
                                               outer_itlist,
                                               OUTER_VAR,
                                               rtoffset,
                                               NRM_EQUAL,
                                               NUM_EXEC_QUAL((Plan *) join));
    }
 
    /*
     * Now we need to fix up the targetlist and qpqual, which are logically
     * above the join.  This means that, if it's not an inner join, any Vars
     * and PHVs appearing here should have nullingrels that include the
     * effects of the outer join, ie they will have nullingrels equal to the
     * input Vars' nullingrels plus the bit added by the outer join.  We don't
     * currently have enough info available here to identify what that should
     * be, so we just tell fix_join_expr to accept superset nullingrels
     * matches instead of exact ones.
     */
    join->plan.targetlist = fix_join_expr(root,
                                          join->plan.targetlist,
                                          outer_itlist,
                                          inner_itlist,
                                          (Index) 0,
                                          rtoffset,
                                          (join->jointype == JOIN_INNER ? NRM_EQUAL : NRM_SUPERSET),
                                          NUM_EXEC_TLIST((Plan *) join));
    join->plan.qual = fix_join_expr(root,
                                    join->plan.qual,
                                    outer_itlist,
                                    inner_itlist,
                                    (Index) 0,
                                    rtoffset,
                                    (join->jointype == JOIN_INNER ? NRM_EQUAL : NRM_SUPERSET),
                                    NUM_EXEC_QUAL((Plan *) join));
 
    pfree(outer_itlist);
    pfree(inner_itlist);
}
 
/*
 * set_upper_references
 *    Update the targetlist and quals of an upper-level plan node
 *    to refer to the tuples returned by its lefttree subplan.
 *    Also perform opcode lookup for these expressions, and
 *    add regclass OIDs to root->glob->relationOids.
 *
 * This is used for single-input plan types like Agg, Group, Result.
 *
 * In most cases, we have to match up individual Vars in the tlist and
 * qual expressions with elements of the subplan's tlist (which was
 * generated by flattening these selfsame expressions, so it should have all
 * the required variables).  There is an important exception, however:
 * depending on where we are in the plan tree, sort/group columns may have
 * been pushed into the subplan tlist unflattened.  If these values are also
 * needed in the output then we want to reference the subplan tlist element
 * rather than recomputing the expression.
 */
static void
set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset)
{
    Plan       *subplan = plan->lefttree;
    indexed_tlist *subplan_itlist;
    List       *output_targetlist;
    ListCell   *l;
 
    subplan_itlist = build_tlist_index(subplan->targetlist);
 
    /*
     * If it's a grouping node with grouping sets, any Vars and PHVs appearing
     * in the targetlist and quals should have nullingrels that include the
     * effects of the grouping step, ie they will have nullingrels equal to
     * the input Vars/PHVs' nullingrels plus the RT index of the grouping
     * step.  In order to perform exact nullingrels matches, we remove the RT
     * index of the grouping step first.
     */
    if (IsA(plan, Agg) &&
        root->group_rtindex > 0 &&
        ((Agg *) plan)->groupingSets)
    {
        plan->targetlist = (List *)
            remove_nulling_relids((Node *) plan->targetlist,
                                  bms_make_singleton(root->group_rtindex),
                                  NULL);
        plan->qual = (List *)
            remove_nulling_relids((Node *) plan->qual,
                                  bms_make_singleton(root->group_rtindex),
                                  NULL);
    }
 
    output_targetlist = NIL;
    foreach(l, plan->targetlist)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(l);
        Node       *newexpr;
 
        /* If it's a sort/group item, first try to match by sortref */
        if (tle->ressortgroupref != 0)
        {
            newexpr = (Node *)
                search_indexed_tlist_for_sortgroupref(tle->expr,
                                                      tle->ressortgroupref,
                                                      subplan_itlist,
                                                      OUTER_VAR);
            if (!newexpr)
                newexpr = fix_upper_expr(root,
                                         (Node *) tle->expr,
                                         subplan_itlist,
                                         OUTER_VAR,
                                         rtoffset,
                                         NRM_EQUAL,
                                         NUM_EXEC_TLIST(plan));
        }
        else
            newexpr = fix_upper_expr(root,
                                     (Node *) tle->expr,
                                     subplan_itlist,
                                     OUTER_VAR,
                                     rtoffset,
                                     NRM_EQUAL,
                                     NUM_EXEC_TLIST(plan));
        tle = flatCopyTargetEntry(tle);
        tle->expr = (Expr *) newexpr;
        output_targetlist = lappend(output_targetlist, tle);
    }
    plan->targetlist = output_targetlist;
 
    plan->qual = (List *)
        fix_upper_expr(root,
                       (Node *) plan->qual,
                       subplan_itlist,
                       OUTER_VAR,
                       rtoffset,
                       NRM_EQUAL,
                       NUM_EXEC_QUAL(plan));
 
    pfree(subplan_itlist);
}
 
/*
 * set_param_references
 *    Initialize the initParam list in Gather or Gather merge node such that
 *    it contains reference of all the params that needs to be evaluated
 *    before execution of the node.  It contains the initplan params that are
 *    being passed to the plan nodes below it.
 */
static void
set_param_references(PlannerInfo *root, Plan *plan)
{
    Assert(IsA(plan, Gather) || IsA(plan, GatherMerge));
 
    if (plan->lefttree->extParam)
    {
        PlannerInfo *proot;
        Bitmapset  *initSetParam = NULL;
        ListCell   *l;
 
        for (proot = root; proot != NULL; proot = proot->parent_root)
        {
            foreach(l, proot->init_plans)
            {
                SubPlan    *initsubplan = (SubPlan *) lfirst(l);
                ListCell   *l2;
 
                foreach(l2, initsubplan->setParam)
                {
                    initSetParam = bms_add_member(initSetParam, lfirst_int(l2));
                }
            }
        }
 
        /*
         * Remember the list of all external initplan params that are used by
         * the children of Gather or Gather merge node.
         */
        if (IsA(plan, Gather))
            ((Gather *) plan)->initParam =
                bms_intersect(plan->lefttree->extParam, initSetParam);
        else
            ((GatherMerge *) plan)->initParam =
                bms_intersect(plan->lefttree->extParam, initSetParam);
    }
}
 
/*
 * Recursively scan an expression tree and convert Aggrefs to the proper
 * intermediate form for combining aggregates.  This means (1) replacing each
 * one's argument list with a single argument that is the original Aggref
 * modified to show partial aggregation and (2) changing the upper Aggref to
 * show combining aggregation.
 *
 * After this step, set_upper_references will replace the partial Aggrefs
 * with Vars referencing the lower Agg plan node's outputs, so that the final
 * form seen by the executor is a combining Aggref with a Var as input.
 *
 * It's rather messy to postpone this step until setrefs.c; ideally it'd be
 * done in createplan.c.  The difficulty is that once we modify the Aggref
 * expressions, they will no longer be equal() to their original form and
 * so cross-plan-node-level matches will fail.  So this has to happen after
 * the plan node above the Agg has resolved its subplan references.
 */
static Node *
convert_combining_aggrefs(Node *node, void *context)
{
    if (node == NULL)
        return NULL;
    if (IsA(node, Aggref))
    {
        Aggref     *orig_agg = (Aggref *) node;
        Aggref     *child_agg;
        Aggref     *parent_agg;
 
        /* Assert we've not chosen to partial-ize any unsupported cases */
        Assert(orig_agg->aggorder == NIL);
        Assert(orig_agg->aggdistinct == NIL);
 
        /*
         * Since aggregate calls can't be nested, we needn't recurse into the
         * arguments.  But for safety, flat-copy the Aggref node itself rather
         * than modifying it in-place.
         */
        child_agg = makeNode(Aggref);
        memcpy(child_agg, orig_agg, sizeof(Aggref));
 
        /*
         * For the parent Aggref, we want to copy all the fields of the
         * original aggregate *except* the args list, which we'll replace
         * below, and the aggfilter expression, which should be applied only
         * by the child not the parent.  Rather than explicitly knowing about
         * all the other fields here, we can momentarily modify child_agg to
         * provide a suitable source for copyObject.
         */
        child_agg->args = NIL;
        child_agg->aggfilter = NULL;
        parent_agg = copyObject(child_agg);
        child_agg->args = orig_agg->args;
        child_agg->aggfilter = orig_agg->aggfilter;
 
        /*
         * Now, set up child_agg to represent the first phase of partial
         * aggregation.  For now, assume serialization is required.
         */
        mark_partial_aggref(child_agg, AGGSPLIT_INITIAL_SERIAL);
 
        /*
         * And set up parent_agg to represent the second phase.
         */
        parent_agg->args = list_make1(makeTargetEntry((Expr *) child_agg,
                                                      1, NULL, false));
        mark_partial_aggref(parent_agg, AGGSPLIT_FINAL_DESERIAL);
 
        return (Node *) parent_agg;
    }
    return expression_tree_mutator(node, convert_combining_aggrefs, context);
}
 
/*
 * set_dummy_tlist_references
 *    Replace the targetlist of an upper-level plan node with a simple
 *    list of OUTER_VAR references to its child.
 *
 * This is used for plan types like Sort and Append that don't evaluate
 * their targetlists.  Although the executor doesn't care at all what's in
 * the tlist, EXPLAIN needs it to be realistic.
 *
 * Note: we could almost use set_upper_references() here, but it fails for
 * Append for lack of a lefttree subplan.  Single-purpose code is faster
 * anyway.
 */
static void
set_dummy_tlist_references(Plan *plan, int rtoffset)
{
    List       *output_targetlist;
    ListCell   *l;
 
    output_targetlist = NIL;
    foreach(l, plan->targetlist)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(l);
        Var        *oldvar = (Var *) tle->expr;
        Var        *newvar;
 
        /*
         * As in search_indexed_tlist_for_non_var(), we prefer to keep Consts
         * as Consts, not Vars referencing Consts.  Here, there's no speed
         * advantage to be had, but it makes EXPLAIN output look cleaner, and
         * again it avoids confusing the executor.
         */
        if (IsA(oldvar, Const))
        {
            /* just reuse the existing TLE node */
            output_targetlist = lappend(output_targetlist, tle);
            continue;
        }
 
        newvar = makeVar(OUTER_VAR,
                         tle->resno,
                         exprType((Node *) oldvar),
                         exprTypmod((Node *) oldvar),
                         exprCollation((Node *) oldvar),
                         0);
        if (IsA(oldvar, Var) &&
            oldvar->varnosyn > 0)
        {
            newvar->varnosyn = oldvar->varnosyn + rtoffset;
            newvar->varattnosyn = oldvar->varattnosyn;
        }
        else
        {
            newvar->varnosyn = 0;   /* wasn't ever a plain Var */
            newvar->varattnosyn = 0;
        }
 
        tle = flatCopyTargetEntry(tle);
        tle->expr = (Expr *) newvar;
        output_targetlist = lappend(output_targetlist, tle);
    }
    plan->targetlist = output_targetlist;
 
    /* We don't touch plan->qual here */
}
 
 
/*
 * build_tlist_index --- build an index data structure for a child tlist
 *
 * In most cases, subplan tlists will be "flat" tlists with only Vars,
 * so we try to optimize that case by extracting information about Vars
 * in advance.  Matching a parent tlist to a child is still an O(N^2)
 * operation, but at least with a much smaller constant factor than plain
 * tlist_member() searches.
 *
 * The result of this function is an indexed_tlist struct to pass to
 * search_indexed_tlist_for_var() and siblings.
 * When done, the indexed_tlist may be freed with a single pfree().
 */
static indexed_tlist *
build_tlist_index(List *tlist)
{
    indexed_tlist *itlist;
    tlist_vinfo *vinfo;
    ListCell   *l;
 
    /* Create data structure with enough slots for all tlist entries */
    itlist = (indexed_tlist *)
        palloc(offsetof(indexed_tlist, vars) +
               list_length(tlist) * sizeof(tlist_vinfo));
 
    itlist->tlist = tlist;
    itlist->has_ph_vars = false;
    itlist->has_non_vars = false;
 
    /* Find the Vars and fill in the index array */
    vinfo = itlist->vars;
    foreach(l, tlist)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(l);
 
        if (tle->expr && IsA(tle->expr, Var))
        {
            Var        *var = (Var *) tle->expr;
 
            vinfo->varno = var->varno;
            vinfo->varattno = var->varattno;
            vinfo->resno = tle->resno;
            vinfo->varnullingrels = var->varnullingrels;
            vinfo++;
        }
        else if (tle->expr && IsA(tle->expr, PlaceHolderVar))
            itlist->has_ph_vars = true;
        else
            itlist->has_non_vars = true;
    }
 
    itlist->num_vars = (vinfo - itlist->vars);
 
    return itlist;
}
 
/*
 * build_tlist_index_other_vars --- build a restricted tlist index
 *
 * This is like build_tlist_index, but we only index tlist entries that
 * are Vars belonging to some rel other than the one specified.  We will set
 * has_ph_vars (allowing PlaceHolderVars to be matched), but not has_non_vars
 * (so nothing other than Vars and PlaceHolderVars can be matched).
 */
static indexed_tlist *
build_tlist_index_other_vars(List *tlist, int ignore_rel)
{
    indexed_tlist *itlist;
    tlist_vinfo *vinfo;
    ListCell   *l;
 
    /* Create data structure with enough slots for all tlist entries */
    itlist = (indexed_tlist *)
        palloc(offsetof(indexed_tlist, vars) +
               list_length(tlist) * sizeof(tlist_vinfo));
 
    itlist->tlist = tlist;
    itlist->has_ph_vars = false;
    itlist->has_non_vars = false;
 
    /* Find the desired Vars and fill in the index array */
    vinfo = itlist->vars;
    foreach(l, tlist)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(l);
 
        if (tle->expr && IsA(tle->expr, Var))
        {
            Var        *var = (Var *) tle->expr;
 
            if (var->varno != ignore_rel)
            {
                vinfo->varno = var->varno;
                vinfo->varattno = var->varattno;
                vinfo->resno = tle->resno;
                vinfo->varnullingrels = var->varnullingrels;
                vinfo++;
            }
        }
        else if (tle->expr && IsA(tle->expr, PlaceHolderVar))
            itlist->has_ph_vars = true;
    }
 
    itlist->num_vars = (vinfo - itlist->vars);
 
    return itlist;
}
 
/*
 * search_indexed_tlist_for_var --- find a Var in an indexed tlist
 *
 * If a match is found, return a copy of the given Var with suitably
 * modified varno/varattno (to wit, newvarno and the resno of the TLE entry).
 * Also ensure that varnosyn is incremented by rtoffset.
 * If no match, return NULL.
 *
 * We cross-check the varnullingrels of the subplan output Var based on
 * nrm_match.  Most call sites should pass NRM_EQUAL indicating we expect
 * an exact match.  However, there are places where we haven't cleaned
 * things up completely, and we have to settle for allowing subset or
 * superset matches.
 */
static Var *
search_indexed_tlist_for_var(Var *var, indexed_tlist *itlist,
                             int newvarno, int rtoffset,
                             NullingRelsMatch nrm_match)
{
    int         varno = var->varno;
    AttrNumber  varattno = var->varattno;
    tlist_vinfo *vinfo;
    int         i;
 
    vinfo = itlist->vars;
    i = itlist->num_vars;
    while (i-- > 0)
    {
        if (vinfo->varno == varno && vinfo->varattno == varattno)
        {
            /* Found a match */
            Var        *newvar = copyVar(var);
 
            /*
             * Verify that we kept all the nullingrels machinations straight.
             *
             * XXX we skip the check for system columns and whole-row Vars.
             * That's because such Vars might be row identity Vars, which are
             * generated without any varnullingrels.  It'd be hard to do
             * otherwise, since they're normally made very early in planning,
             * when we haven't looked at the jointree yet and don't know which
             * joins might null such Vars.  Doesn't seem worth the expense to
             * make them fully valid.  (While it's slightly annoying that we
             * thereby lose checking for user-written references to such
             * columns, it seems unlikely that a bug in nullingrels logic
             * would affect only system columns.)
             */
            if (!(varattno <= 0 ||
                  (nrm_match == NRM_SUBSET ?
                   bms_is_subset(var->varnullingrels, vinfo->varnullingrels) :
                   nrm_match == NRM_SUPERSET ?
                   bms_is_subset(vinfo->varnullingrels, var->varnullingrels) :
                   bms_equal(vinfo->varnullingrels, var->varnullingrels))))
                elog(ERROR, "wrong varnullingrels %s (expected %s) for Var %d/%d",
                     bmsToString(var->varnullingrels),
                     bmsToString(vinfo->varnullingrels),
                     varno, varattno);
 
            newvar->varno = newvarno;
            newvar->varattno = vinfo->resno;
            if (newvar->varnosyn > 0)
                newvar->varnosyn += rtoffset;
            return newvar;
        }
        vinfo++;
    }
    return NULL;                /* no match */
}
 
/*
 * search_indexed_tlist_for_phv --- find a PlaceHolderVar in an indexed tlist
 *
 * If a match is found, return a Var constructed to reference the tlist item.
 * If no match, return NULL.
 *
 * Cross-check phnullingrels as in search_indexed_tlist_for_var.
 *
 * NOTE: it is a waste of time to call this unless itlist->has_ph_vars.
 */
static Var *
search_indexed_tlist_for_phv(PlaceHolderVar *phv,
                             indexed_tlist *itlist, int newvarno,
                             NullingRelsMatch nrm_match)
{
    ListCell   *lc;
 
    foreach(lc, itlist->tlist)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(lc);
 
        if (tle->expr && IsA(tle->expr, PlaceHolderVar))
        {
            PlaceHolderVar *subphv = (PlaceHolderVar *) tle->expr;
            Var        *newvar;
 
            /*
             * Analogously to search_indexed_tlist_for_var, we match on phid
             * only.  We don't use equal(), partially for speed but mostly
             * because phnullingrels might not be exactly equal.
             */
            if (phv->phid != subphv->phid)
                continue;
 
            /* Verify that we kept all the nullingrels machinations straight */
            if (!(nrm_match == NRM_SUBSET ?
                  bms_is_subset(phv->phnullingrels, subphv->phnullingrels) :
                  nrm_match == NRM_SUPERSET ?
                  bms_is_subset(subphv->phnullingrels, phv->phnullingrels) :
                  bms_equal(subphv->phnullingrels, phv->phnullingrels)))
                elog(ERROR, "wrong phnullingrels %s (expected %s) for PlaceHolderVar %d",
                     bmsToString(phv->phnullingrels),
                     bmsToString(subphv->phnullingrels),
                     phv->phid);
 
            /* Found a matching subplan output expression */
            newvar = makeVarFromTargetEntry(newvarno, tle);
            newvar->varnosyn = 0;   /* wasn't ever a plain Var */
            newvar->varattnosyn = 0;
            return newvar;
        }
    }
    return NULL;                /* no match */
}
 
/*
 * search_indexed_tlist_for_non_var --- find a non-Var/PHV in an indexed tlist
 *
 * If a match is found, return a Var constructed to reference the tlist item.
 * If no match, return NULL.
 *
 * NOTE: it is a waste of time to call this unless itlist->has_non_vars.
 */
static Var *
search_indexed_tlist_for_non_var(Expr *node,
                                 indexed_tlist *itlist, int newvarno)
{
    TargetEntry *tle;
 
    /*
     * If it's a simple Const, replacing it with a Var is silly, even if there
     * happens to be an identical Const below; a Var is more expensive to
     * execute than a Const.  What's more, replacing it could confuse some
     * places in the executor that expect to see simple Consts for, eg,
     * dropped columns.
     */
    if (IsA(node, Const))
        return NULL;
 
    tle = tlist_member(node, itlist->tlist);
    if (tle)
    {
        /* Found a matching subplan output expression */
        Var        *newvar;
 
        newvar = makeVarFromTargetEntry(newvarno, tle);
        newvar->varnosyn = 0;   /* wasn't ever a plain Var */
        newvar->varattnosyn = 0;
        return newvar;
    }
    return NULL;                /* no match */
}
 
/*
 * search_indexed_tlist_for_sortgroupref --- find a sort/group expression
 *
 * If a match is found, return a Var constructed to reference the tlist item.
 * If no match, return NULL.
 *
 * This is needed to ensure that we select the right subplan TLE in cases
 * where there are multiple textually-equal()-but-volatile sort expressions.
 * And it's also faster than search_indexed_tlist_for_non_var.
 */
static Var *
search_indexed_tlist_for_sortgroupref(Expr *node,
                                      Index sortgroupref,
                                      indexed_tlist *itlist,
                                      int newvarno)
{
    ListCell   *lc;
 
    foreach(lc, itlist->tlist)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(lc);
 
        /*
         * Usually the equal() check is redundant, but in setop plans it may
         * not be, since prepunion.c assigns ressortgroupref equal to the
         * column resno without regard to whether that matches the topmost
         * level's sortgrouprefs and without regard to whether any implicit
         * coercions are added in the setop tree.  We might have to clean that
         * up someday; but for now, just ignore any false matches.
         */
        if (tle->ressortgroupref == sortgroupref &&
            equal(node, tle->expr))
        {
            /* Found a matching subplan output expression */
            Var        *newvar;
 
            newvar = makeVarFromTargetEntry(newvarno, tle);
            newvar->varnosyn = 0;   /* wasn't ever a plain Var */
            newvar->varattnosyn = 0;
            return newvar;
        }
    }
    return NULL;                /* no match */
}
 
/*
 * fix_join_expr
 *     Create a new set of targetlist entries or join qual clauses by
 *     changing the varno/varattno values of variables in the clauses
 *     to reference target list values from the outer and inner join
 *     relation target lists.  Also perform opcode lookup and add
 *     regclass OIDs to root->glob->relationOids.
 *
 * This is used in four different scenarios:
 * 1) a normal join clause, where all the Vars in the clause *must* be
 *    replaced by OUTER_VAR or INNER_VAR references.  In this case
 *    acceptable_rel should be zero so that any failure to match a Var will be
 *    reported as an error.
 * 2) RETURNING clauses, which may contain both Vars of the target relation
 *    and Vars of other relations. In this case we want to replace the
 *    other-relation Vars by OUTER_VAR references, while leaving target Vars
 *    alone. Thus inner_itlist = NULL and acceptable_rel = the ID of the
 *    target relation should be passed.
 * 3) ON CONFLICT UPDATE SET/WHERE clauses.  Here references to EXCLUDED are
 *    to be replaced with INNER_VAR references, while leaving target Vars (the
 *    to-be-updated relation) alone. Correspondingly inner_itlist is to be
 *    EXCLUDED elements, outer_itlist = NULL and acceptable_rel the target
 *    relation.
 * 4) MERGE.  In this case, references to the source relation are to be
 *    replaced with INNER_VAR references, leaving Vars of the target
 *    relation (the to-be-modified relation) alone.  So inner_itlist is to be
 *    the source relation elements, outer_itlist = NULL and acceptable_rel
 *    the target relation.
 *
 * 'clauses' is the targetlist or list of join clauses
 * 'outer_itlist' is the indexed target list of the outer join relation,
 *      or NULL
 * 'inner_itlist' is the indexed target list of the inner join relation,
 *      or NULL
 * 'acceptable_rel' is either zero or the rangetable index of a relation
 *      whose Vars may appear in the clause without provoking an error
 * 'rtoffset': how much to increment varnos by
 * 'nrm_match': as for search_indexed_tlist_for_var()
 * 'num_exec': estimated number of executions of expression
 *
 * Returns the new expression tree.  The original clause structure is
 * not modified.
 */
static List *
fix_join_expr(PlannerInfo *root,
              List *clauses,
              indexed_tlist *outer_itlist,
              indexed_tlist *inner_itlist,
              Index acceptable_rel,
              int rtoffset,
              NullingRelsMatch nrm_match,
              double num_exec)
{
    fix_join_expr_context context;
 
    context.root = root;
    context.outer_itlist = outer_itlist;
    context.inner_itlist = inner_itlist;
    context.acceptable_rel = acceptable_rel;
    context.rtoffset = rtoffset;
    context.nrm_match = nrm_match;
    context.num_exec = num_exec;
    return (List *) fix_join_expr_mutator((Node *) clauses, &context);
}
 
static Node *
fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
{
    Var        *newvar;
 
    if (node == NULL)
        return NULL;
    if (IsA(node, Var))
    {
        Var        *var = (Var *) node;
 
        /*
         * Verify that Vars with non-default varreturningtype only appear in
         * the RETURNING list, and refer to the target relation.
         */
        if (var->varreturningtype != VAR_RETURNING_DEFAULT)
        {
            if (context->inner_itlist != NULL ||
                context->outer_itlist == NULL ||
                context->acceptable_rel == 0)
                elog(ERROR, "variable returning old/new found outside RETURNING list");
            if (var->varno != context->acceptable_rel)
                elog(ERROR, "wrong varno %d (expected %d) for variable returning old/new",
                     var->varno, context->acceptable_rel);
        }
 
        /* Look for the var in the input tlists, first in the outer */
        if (context->outer_itlist)
        {
            newvar = search_indexed_tlist_for_var(var,
                                                  context->outer_itlist,
                                                  OUTER_VAR,
                                                  context->rtoffset,
                                                  context->nrm_match);
            if (newvar)
                return (Node *) newvar;
        }
 
        /* then in the inner. */
        if (context->inner_itlist)
        {
            newvar = search_indexed_tlist_for_var(var,
                                                  context->inner_itlist,
                                                  INNER_VAR,
                                                  context->rtoffset,
                                                  context->nrm_match);
            if (newvar)
                return (Node *) newvar;
        }
 
        /* If it's for acceptable_rel, adjust and return it */
        if (var->varno == context->acceptable_rel)
        {
            var = copyVar(var);
            var->varno += context->rtoffset;
            if (var->varnosyn > 0)
                var->varnosyn += context->rtoffset;
            return (Node *) var;
        }
 
        /* No referent found for Var */
        elog(ERROR, "variable not found in subplan target lists");
    }
    if (IsA(node, PlaceHolderVar))
    {
        PlaceHolderVar *phv = (PlaceHolderVar *) node;
 
        /* See if the PlaceHolderVar has bubbled up from a lower plan node */
        if (context->outer_itlist && context->outer_itlist->has_ph_vars)
        {
            newvar = search_indexed_tlist_for_phv(phv,
                                                  context->outer_itlist,
                                                  OUTER_VAR,
                                                  context->nrm_match);
            if (newvar)
                return (Node *) newvar;
        }
        if (context->inner_itlist && context->inner_itlist->has_ph_vars)
        {
            newvar = search_indexed_tlist_for_phv(phv,
                                                  context->inner_itlist,
                                                  INNER_VAR,
                                                  context->nrm_match);
            if (newvar)
                return (Node *) newvar;
        }
 
        /* If not supplied by input plans, evaluate the contained expr */
        /* XXX can we assert something about phnullingrels? */
        return fix_join_expr_mutator((Node *) phv->phexpr, context);
    }
    /* Try matching more complex expressions too, if tlists have any */
    if (context->outer_itlist && context->outer_itlist->has_non_vars)
    {
        newvar = search_indexed_tlist_for_non_var((Expr *) node,
                                                  context->outer_itlist,
                                                  OUTER_VAR);
        if (newvar)
            return (Node *) newvar;
    }
    if (context->inner_itlist && context->inner_itlist->has_non_vars)
    {
        newvar = search_indexed_tlist_for_non_var((Expr *) node,
                                                  context->inner_itlist,
                                                  INNER_VAR);
        if (newvar)
            return (Node *) newvar;
    }
    /* Special cases (apply only AFTER failing to match to lower tlist) */
    if (IsA(node, Param))
        return fix_param_node(context->root, (Param *) node);
    if (IsA(node, AlternativeSubPlan))
        return fix_join_expr_mutator(fix_alternative_subplan(context->root,
                                                             (AlternativeSubPlan *) node,
                                                             context->num_exec),
                                     context);
    fix_expr_common(context->root, node);
    return expression_tree_mutator(node, fix_join_expr_mutator, context);
}
 
/*
 * fix_upper_expr
 *      Modifies an expression tree so that all Var nodes reference outputs
 *      of a subplan.  Also looks for Aggref nodes that should be replaced
 *      by initplan output Params.  Also performs opcode lookup, and adds
 *      regclass OIDs to root->glob->relationOids.
 *
 * This is used to fix up target and qual expressions of non-join upper-level
 * plan nodes, as well as index-only scan nodes.
 *
 * An error is raised if no matching var can be found in the subplan tlist
 * --- so this routine should only be applied to nodes whose subplans'
 * targetlists were generated by flattening the expressions used in the
 * parent node.
 *
 * If itlist->has_non_vars is true, then we try to match whole subexpressions
 * against elements of the subplan tlist, so that we can avoid recomputing
 * expressions that were already computed by the subplan.  (This is relatively
 * expensive, so we don't want to try it in the common case where the
 * subplan tlist is just a flattened list of Vars.)
 *
 * 'node': the tree to be fixed (a target item or qual)
 * 'subplan_itlist': indexed target list for subplan (or index)
 * 'newvarno': varno to use for Vars referencing tlist elements
 * 'rtoffset': how much to increment varnos by
 * 'nrm_match': as for search_indexed_tlist_for_var()
 * 'num_exec': estimated number of executions of expression
 *
 * The resulting tree is a copy of the original in which all Var nodes have
 * varno = newvarno, varattno = resno of corresponding targetlist element.
 * The original tree is not modified.
 */
static Node *
fix_upper_expr(PlannerInfo *root,
               Node *node,
               indexed_tlist *subplan_itlist,
               int newvarno,
               int rtoffset,
               NullingRelsMatch nrm_match,
               double num_exec)
{
    fix_upper_expr_context context;
 
    context.root = root;
    context.subplan_itlist = subplan_itlist;
    context.newvarno = newvarno;
    context.rtoffset = rtoffset;
    context.nrm_match = nrm_match;
    context.num_exec = num_exec;
    return fix_upper_expr_mutator(node, &context);
}
 
static Node *
fix_upper_expr_mutator(Node *node, fix_upper_expr_context *context)
{
    Var        *newvar;
 
    if (node == NULL)
        return NULL;
    if (IsA(node, Var))
    {
        Var        *var = (Var *) node;
 
        newvar = search_indexed_tlist_for_var(var,
                                              context->subplan_itlist,
                                              context->newvarno,
                                              context->rtoffset,
                                              context->nrm_match);
        if (!newvar)
            elog(ERROR, "variable not found in subplan target list");
        return (Node *) newvar;
    }
    if (IsA(node, PlaceHolderVar))
    {
        PlaceHolderVar *phv = (PlaceHolderVar *) node;
 
        /* See if the PlaceHolderVar has bubbled up from a lower plan node */
        if (context->subplan_itlist->has_ph_vars)
        {
            newvar = search_indexed_tlist_for_phv(phv,
                                                  context->subplan_itlist,
                                                  context->newvarno,
                                                  context->nrm_match);
            if (newvar)
                return (Node *) newvar;
        }
        /* If not supplied by input plan, evaluate the contained expr */
        /* XXX can we assert something about phnullingrels? */
        return fix_upper_expr_mutator((Node *) phv->phexpr, context);
    }
    /* Try matching more complex expressions too, if tlist has any */
    if (context->subplan_itlist->has_non_vars)
    {
        newvar = search_indexed_tlist_for_non_var((Expr *) node,
                                                  context->subplan_itlist,
                                                  context->newvarno);
        if (newvar)
            return (Node *) newvar;
    }
    /* Special cases (apply only AFTER failing to match to lower tlist) */
    if (IsA(node, Param))
        return fix_param_node(context->root, (Param *) node);
    if (IsA(node, Aggref))
    {
        Aggref     *aggref = (Aggref *) node;
        Param      *aggparam;
 
        /* See if the Aggref should be replaced by a Param */
        aggparam = find_minmax_agg_replacement_param(context->root, aggref);
        if (aggparam != NULL)
        {
            /* Make a copy of the Param for paranoia's sake */
            return (Node *) copyObject(aggparam);
        }
        /* If no match, just fall through to process it normally */
    }
    if (IsA(node, AlternativeSubPlan))
        return fix_upper_expr_mutator(fix_alternative_subplan(context->root,
                                                              (AlternativeSubPlan *) node,
                                                              context->num_exec),
                                      context);
    fix_expr_common(context->root, node);
    return expression_tree_mutator(node, fix_upper_expr_mutator, context);
}
 
/*
 * set_returning_clause_references
 *      Perform setrefs.c's work on a RETURNING targetlist
 *
 * If the query involves more than just the result table, we have to
 * adjust any Vars that refer to other tables to reference junk tlist
 * entries in the top subplan's targetlist.  Vars referencing the result
 * table should be left alone, however (the executor will evaluate them
 * using the actual heap tuple, after firing triggers if any).  In the
 * adjusted RETURNING list, result-table Vars will have their original
 * varno (plus rtoffset), but Vars for other rels will have varno OUTER_VAR.
 *
 * We also must perform opcode lookup and add regclass OIDs to
 * root->glob->relationOids.
 *
 * 'rlist': the RETURNING targetlist to be fixed
 * 'topplan': the top subplan node that will be just below the ModifyTable
 *      node (note it's not yet passed through set_plan_refs)
 * 'resultRelation': RT index of the associated result relation
 * 'rtoffset': how much to increment varnos by
 *
 * Note: the given 'root' is for the parent query level, not the 'topplan'.
 * This does not matter currently since we only access the dependency-item
 * lists in root->glob, but it would need some hacking if we wanted a root
 * that actually matches the subplan.
 *
 * Note: resultRelation is not yet adjusted by rtoffset.
 */
static List *
set_returning_clause_references(PlannerInfo *root,
                                List *rlist,
                                Plan *topplan,
                                Index resultRelation,
                                int rtoffset)
{
    indexed_tlist *itlist;
 
    /*
     * We can perform the desired Var fixup by abusing the fix_join_expr
     * machinery that formerly handled inner indexscan fixup.  We search the
     * top plan's targetlist for Vars of non-result relations, and use
     * fix_join_expr to convert RETURNING Vars into references to those tlist
     * entries, while leaving result-rel Vars as-is.
     *
     * PlaceHolderVars will also be sought in the targetlist, but no
     * more-complex expressions will be.  Note that it is not possible for a
     * PlaceHolderVar to refer to the result relation, since the result is
     * never below an outer join.  If that case could happen, we'd have to be
     * prepared to pick apart the PlaceHolderVar and evaluate its contained
     * expression instead.
     */
    itlist = build_tlist_index_other_vars(topplan->targetlist, resultRelation);
 
    rlist = fix_join_expr(root,
                          rlist,
                          itlist,
                          NULL,
                          resultRelation,
                          rtoffset,
                          NRM_EQUAL,
                          NUM_EXEC_TLIST(topplan));
 
    pfree(itlist);
 
    return rlist;
}
 
/*
 * fix_windowagg_condition_expr_mutator
 *      Mutator function for replacing WindowFuncs with the corresponding Var
 *      in the targetlist which references that WindowFunc.
 */
static Node *
fix_windowagg_condition_expr_mutator(Node *node,
                                     fix_windowagg_cond_context *context)
{
    if (node == NULL)
        return NULL;
 
    if (IsA(node, WindowFunc))
    {
        Var        *newvar;
 
        newvar = search_indexed_tlist_for_non_var((Expr *) node,
                                                  context->subplan_itlist,
                                                  context->newvarno);
        if (newvar)
            return (Node *) newvar;
        elog(ERROR, "WindowFunc not found in subplan target lists");
    }
 
    return expression_tree_mutator(node,
                                   fix_windowagg_condition_expr_mutator,
                                   context);
}
 
/*
 * fix_windowagg_condition_expr
 *      Converts references in 'runcondition' so that any WindowFunc
 *      references are swapped out for a Var which references the matching
 *      WindowFunc in 'subplan_itlist'.
 */
static List *
fix_windowagg_condition_expr(PlannerInfo *root,
                             List *runcondition,
                             indexed_tlist *subplan_itlist)
{
    fix_windowagg_cond_context context;
 
    context.root = root;
    context.subplan_itlist = subplan_itlist;
    context.newvarno = 0;
 
    return (List *) fix_windowagg_condition_expr_mutator((Node *) runcondition,
                                                         &context);
}
 
/*
 * set_windowagg_runcondition_references
 *      Converts references in 'runcondition' so that any WindowFunc
 *      references are swapped out for a Var which references the matching
 *      WindowFunc in 'plan' targetlist.
 */
static List *
set_windowagg_runcondition_references(PlannerInfo *root,
                                      List *runcondition,
                                      Plan *plan)
{
    List       *newlist;
    indexed_tlist *itlist;
 
    itlist = build_tlist_index(plan->targetlist);
 
    newlist = fix_windowagg_condition_expr(root, runcondition, itlist);
 
    pfree(itlist);
 
    return newlist;
}
 
/*
 * find_minmax_agg_replacement_param
 *      If the given Aggref is one that we are optimizing into a subquery
 *      (cf. planagg.c), then return the Param that should replace it.
 *      Else return NULL.
 *
 * This is exported so that SS_finalize_plan can use it before setrefs.c runs.
 * Note that it will not find anything until we have built a Plan from a
 * MinMaxAggPath, as root->minmax_aggs will never be filled otherwise.
 */
Param *
find_minmax_agg_replacement_param(PlannerInfo *root, Aggref *aggref)
{
    if (root->minmax_aggs != NIL &&
        list_length(aggref->args) == 1)
    {
        TargetEntry *curTarget = (TargetEntry *) linitial(aggref->args);
        ListCell   *lc;
 
        foreach(lc, root->minmax_aggs)
        {
            MinMaxAggInfo *mminfo = (MinMaxAggInfo *) lfirst(lc);
 
            if (mminfo->aggfnoid == aggref->aggfnoid &&
                equal(mminfo->target, curTarget->expr))
                return mminfo->param;
        }
    }
    return NULL;
}
 
 
/*****************************************************************************
 *                  QUERY DEPENDENCY MANAGEMENT
 *****************************************************************************/
 
/*
 * record_plan_function_dependency
 *      Mark the current plan as depending on a particular function.
 *
 * This is exported so that the function-inlining code can record a
 * dependency on a function that it's removed from the plan tree.
 */
void
record_plan_function_dependency(PlannerInfo *root, Oid funcid)
{
    /*
     * For performance reasons, we don't bother to track built-in functions;
     * we just assume they'll never change (or at least not in ways that'd
     * invalidate plans using them).  For this purpose we can consider a
     * built-in function to be one with OID less than FirstUnpinnedObjectId.
     * Note that the OID generator guarantees never to generate such an OID
     * after startup, even at OID wraparound.
     */
    if (funcid >= (Oid) FirstUnpinnedObjectId)
    {
        PlanInvalItem *inval_item = makeNode(PlanInvalItem);
 
        /*
         * It would work to use any syscache on pg_proc, but the easiest is
         * PROCOID since we already have the function's OID at hand.  Note
         * that plancache.c knows we use PROCOID.
         */
        inval_item->cacheId = PROCOID;
        inval_item->hashValue = GetSysCacheHashValue1(PROCOID,
                                                      ObjectIdGetDatum(funcid));
 
        root->glob->invalItems = lappend(root->glob->invalItems, inval_item);
    }
}
 
/*
 * record_plan_type_dependency
 *      Mark the current plan as depending on a particular type.
 *
 * This is exported so that eval_const_expressions can record a
 * dependency on a domain that it's removed a CoerceToDomain node for.
 *
 * We don't currently need to record dependencies on domains that the
 * plan contains CoerceToDomain nodes for, though that might change in
 * future.  Hence, this isn't actually called in this module, though
 * someday fix_expr_common might call it.
 */
void
record_plan_type_dependency(PlannerInfo *root, Oid typid)
{
    /*
     * As in record_plan_function_dependency, ignore the possibility that
     * someone would change a built-in domain.
     */
    if (typid >= (Oid) FirstUnpinnedObjectId)
    {
        PlanInvalItem *inval_item = makeNode(PlanInvalItem);
 
        /*
         * It would work to use any syscache on pg_type, but the easiest is
         * TYPEOID since we already have the type's OID at hand.  Note that
         * plancache.c knows we use TYPEOID.
         */
        inval_item->cacheId = TYPEOID;
        inval_item->hashValue = GetSysCacheHashValue1(TYPEOID,
                                                      ObjectIdGetDatum(typid));
 
        root->glob->invalItems = lappend(root->glob->invalItems, inval_item);
    }
}
 
/*
 * extract_query_dependencies
 *      Given a rewritten, but not yet planned, query or queries
 *      (i.e. a Query node or list of Query nodes), extract dependencies
 *      just as set_plan_references would do.  Also detect whether any
 *      rewrite steps were affected by RLS.
 *
 * This is needed by plancache.c to handle invalidation of cached unplanned
 * queries.
 *
 * Note: this does not go through eval_const_expressions, and hence doesn't
 * reflect its additions of inlined functions and elided CoerceToDomain nodes
 * to the invalItems list.  This is obviously OK for functions, since we'll
 * see them in the original query tree anyway.  For domains, it's OK because
 * we don't care about domains unless they get elided.  That is, a plan might
 * have domain dependencies that the query tree doesn't.
 */
void
extract_query_dependencies(Node *query,
                           List **relationOids,
                           List **invalItems,
                           bool *hasRowSecurity)
{
    PlannerGlobal glob;
    PlannerInfo root;
 
    /* Make up dummy planner state so we can use this module's machinery */
    MemSet(&glob, 0, sizeof(glob));
    glob.type = T_PlannerGlobal;
    glob.relationOids = NIL;
    glob.invalItems = NIL;
    /* Hack: we use glob.dependsOnRole to collect hasRowSecurity flags */
    glob.dependsOnRole = false;
 
    MemSet(&root, 0, sizeof(root));
    root.type = T_PlannerInfo;
    root.glob = &glob;
 
    (void) extract_query_dependencies_walker(query, &root);
 
    *relationOids = glob.relationOids;
    *invalItems = glob.invalItems;
    *hasRowSecurity = glob.dependsOnRole;
}
 
/*
 * Tree walker for extract_query_dependencies.
 *
 * This is exported so that expression_planner_with_deps can call it on
 * simple expressions (post-planning, not before planning, in that case).
 * In that usage, glob.dependsOnRole isn't meaningful, but the relationOids
 * and invalItems lists are added to as needed.
 */
bool
extract_query_dependencies_walker(Node *node, PlannerInfo *context)
{
    if (node == NULL)
        return false;
    Assert(!IsA(node, PlaceHolderVar));
    if (IsA(node, Query))
    {
        Query      *query = (Query *) node;
        ListCell   *lc;
 
        if (query->commandType == CMD_UTILITY)
        {
            /*
             * This logic must handle any utility command for which parse
             * analysis was nontrivial (cf. stmt_requires_parse_analysis).
             *
             * Notably, CALL requires its own processing.
             */
            if (IsA(query->utilityStmt, CallStmt))
            {
                CallStmt   *callstmt = (CallStmt *) query->utilityStmt;
 
                /* We need not examine funccall, just the transformed exprs */
                (void) extract_query_dependencies_walker((Node *) callstmt->funcexpr,
                                                         context);
                (void) extract_query_dependencies_walker((Node *) callstmt->outargs,
                                                         context);
                return false;
            }
 
            /*
             * Ignore other utility statements, except those (such as EXPLAIN)
             * that contain a parsed-but-not-planned query.  For those, we
             * just need to transfer our attention to the contained query.
             */
            query = UtilityContainsQuery(query->utilityStmt);
            if (query == NULL)
                return false;
        }
 
        /* Remember if any Query has RLS quals applied by rewriter */
        if (query->hasRowSecurity)
            context->glob->dependsOnRole = true;
 
        /* Collect relation OIDs in this Query's rtable */
        foreach(lc, query->rtable)
        {
            RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
 
            if (rte->rtekind == RTE_RELATION ||
                (rte->rtekind == RTE_SUBQUERY && OidIsValid(rte->relid)) ||
                (rte->rtekind == RTE_NAMEDTUPLESTORE && OidIsValid(rte->relid)))
                context->glob->relationOids =
                    lappend_oid(context->glob->relationOids, rte->relid);
        }
 
        /* And recurse into the query's subexpressions */
        return query_tree_walker(query, extract_query_dependencies_walker,
                                 context, 0);
    }
    /* Extract function dependencies and check for regclass Consts */
    fix_expr_common(context, node);
    return expression_tree_walker(node, extract_query_dependencies_walker,
                                  context);
}