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setrefs.c

/*-------------------------------------------------------------------------
 *
 * setrefs.c
 *      Post-processing of a completed plan tree: fix references to subplan
 *      vars, compute regproc values for operators, etc
 *
 * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *      $PostgreSQL: pgsql/src/backend/optimizer/plan/setrefs.c,v 1.150.2.1 2009/11/16 18:04:47 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/transam.h"
#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/planmain.h"
#include "optimizer/tlist.h"
#include "parser/parsetree.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"


00030 typedef struct
{
      Index       varno;                  /* RT index of Var */
      AttrNumber  varattno;         /* attr number of Var */
      AttrNumber  resno;                  /* TLE position of Var */
} tlist_vinfo;

00037 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? */
      /* array of num_vars entries: */
      tlist_vinfo vars[1];          /* VARIABLE LENGTH ARRAY */
} indexed_tlist;                    /* VARIABLE LENGTH STRUCT */

00047 typedef struct
{
      PlannerGlobal *glob;
      int               rtoffset;
} fix_scan_expr_context;

00053 typedef struct
{
      PlannerGlobal *glob;
      indexed_tlist *outer_itlist;
      indexed_tlist *inner_itlist;
      Index       acceptable_rel;
      int               rtoffset;
} fix_join_expr_context;

00062 typedef struct
{
      PlannerGlobal *glob;
      indexed_tlist *subplan_itlist;
      int               rtoffset;
} fix_upper_expr_context;

/*
 * 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(glob, lst, rtoffset) \
      ((List *) fix_scan_expr(glob, (Node *) (lst), rtoffset))

static Plan *set_plan_refs(PlannerGlobal *glob, Plan *plan, int rtoffset);
static Plan *set_subqueryscan_references(PlannerGlobal *glob,
                                          SubqueryScan *plan,
                                          int rtoffset);
static bool trivial_subqueryscan(SubqueryScan *plan);
static Node *fix_scan_expr(PlannerGlobal *glob, Node *node, int rtoffset);
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(PlannerGlobal *glob, Join *join, int rtoffset);
static void set_inner_join_references(PlannerGlobal *glob, Plan *inner_plan,
                                      indexed_tlist *outer_itlist);
static void set_upper_references(PlannerGlobal *glob, Plan *plan, int rtoffset);
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,
                                           Index newvarno,
                                           int rtoffset);
static Var *search_indexed_tlist_for_non_var(Node *node,
                                                 indexed_tlist *itlist,
                                                 Index newvarno);
static Var *search_indexed_tlist_for_sortgroupref(Node *node,
                                                        Index sortgroupref,
                                                        indexed_tlist *itlist,
                                                        Index newvarno);
static List *fix_join_expr(PlannerGlobal *glob,
                    List *clauses,
                    indexed_tlist *outer_itlist,
                    indexed_tlist *inner_itlist,
                    Index acceptable_rel, int rtoffset);
static Node *fix_join_expr_mutator(Node *node,
                                fix_join_expr_context *context);
static Node *fix_upper_expr(PlannerGlobal *glob,
                     Node *node,
                     indexed_tlist *subplan_itlist,
                     int rtoffset);
static Node *fix_upper_expr_mutator(Node *node,
                                 fix_upper_expr_context *context);
static bool fix_opfuncids_walker(Node *node, void *context);
static bool extract_query_dependencies_walker(Node *node,
                                                  PlannerGlobal *context);


/*****************************************************************************
 *
 *          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. We compute regproc OIDs for operators (ie, we look up the function
 * that implements each op).
 *
 * 5. 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 and user-defined functions are the only types of
 * objects that are explicitly tracked this way.
 *
 * We also perform one final optimization step, which is to delete
 * SubqueryScan plan nodes that aren't doing anything useful (ie, have
 * no qual and a no-op targetlist).  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 subquery's top tlist
 * wouldn't match up with the Vars in the outer plan tree.  The 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.
 *
 * set_plan_references recursively traverses the whole plan tree.
 *
 * Inputs:
 *    glob: global data for planner run
 *    plan: the topmost node of the plan
 *    rtable: the rangetable for the current subquery
 *
 * The return value is normally the same Plan node passed in, but can be
 * different when the passed-in Plan is a SubqueryScan we decide isn't needed.
 *
 * The flattened rangetable entries are appended to glob->finalrtable, and
 * plan dependencies are appended to glob->relationOids (for relations)
 * and 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(PlannerGlobal *glob, Plan *plan, List *rtable)
{
      int               rtoffset = list_length(glob->finalrtable);
      ListCell   *lc;

      /*
       * 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 alias and eref Alias fields, which
       * are needed by EXPLAIN, and the selectedCols and modifiedCols bitmaps,
       * which are needed for executor-startup permissions checking.
       */
      foreach(lc, rtable)
      {
            RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
            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->subquery = NULL;
            newrte->joinaliasvars = NIL;
            newrte->funcexpr = NULL;
            newrte->funccoltypes = NIL;
            newrte->funccoltypmods = NIL;
            newrte->values_lists = NIL;
            newrte->ctecoltypes = NIL;
            newrte->ctecoltypmods = NIL;

            glob->finalrtable = lappend(glob->finalrtable, newrte);

            /*
             * If it's a plain relation RTE, add the table to relationOids.
             *
             * 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 duplicate list entries.  We could,
             * but it would probably cost more cycles than it would save.
             */
            if (newrte->rtekind == RTE_RELATION)
                  glob->relationOids = lappend_oid(glob->relationOids,
                                                                   newrte->relid);
      }

      /* Now fix the Plan tree */
      return set_plan_refs(glob, plan, rtoffset);
}

/*
 * set_plan_refs: recurse through the Plan nodes of a single subquery level
 */
static Plan *
set_plan_refs(PlannerGlobal *glob, Plan *plan, int rtoffset)
{
      ListCell   *l;

      if (plan == NULL)
            return NULL;

      /*
       * Plan-type-specific fixes
       */
      switch (nodeTag(plan))
      {
            case T_SeqScan:
                  {
                        SeqScan    *splan = (SeqScan *) plan;

                        splan->scanrelid += rtoffset;
                        splan->plan.targetlist =
                              fix_scan_list(glob, splan->plan.targetlist, rtoffset);
                        splan->plan.qual =
                              fix_scan_list(glob, splan->plan.qual, rtoffset);
                  }
                  break;
            case T_IndexScan:
                  {
                        IndexScan  *splan = (IndexScan *) plan;

                        splan->scan.scanrelid += rtoffset;
                        splan->scan.plan.targetlist =
                              fix_scan_list(glob, splan->scan.plan.targetlist, rtoffset);
                        splan->scan.plan.qual =
                              fix_scan_list(glob, splan->scan.plan.qual, rtoffset);
                        splan->indexqual =
                              fix_scan_list(glob, splan->indexqual, rtoffset);
                        splan->indexqualorig =
                              fix_scan_list(glob, splan->indexqualorig, 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(glob, splan->indexqual, rtoffset);
                        splan->indexqualorig =
                              fix_scan_list(glob, splan->indexqualorig, rtoffset);
                  }
                  break;
            case T_BitmapHeapScan:
                  {
                        BitmapHeapScan *splan = (BitmapHeapScan *) plan;

                        splan->scan.scanrelid += rtoffset;
                        splan->scan.plan.targetlist =
                              fix_scan_list(glob, splan->scan.plan.targetlist, rtoffset);
                        splan->scan.plan.qual =
                              fix_scan_list(glob, splan->scan.plan.qual, rtoffset);
                        splan->bitmapqualorig =
                              fix_scan_list(glob, splan->bitmapqualorig, rtoffset);
                  }
                  break;
            case T_TidScan:
                  {
                        TidScan    *splan = (TidScan *) plan;

                        splan->scan.scanrelid += rtoffset;
                        splan->scan.plan.targetlist =
                              fix_scan_list(glob, splan->scan.plan.targetlist, rtoffset);
                        splan->scan.plan.qual =
                              fix_scan_list(glob, splan->scan.plan.qual, rtoffset);
                        splan->tidquals =
                              fix_scan_list(glob, splan->tidquals, rtoffset);
                  }
                  break;
            case T_SubqueryScan:
                  /* Needs special treatment, see comments below */
                  return set_subqueryscan_references(glob,
                                                                     (SubqueryScan *) plan,
                                                                     rtoffset);
            case T_FunctionScan:
                  {
                        FunctionScan *splan = (FunctionScan *) plan;

                        splan->scan.scanrelid += rtoffset;
                        splan->scan.plan.targetlist =
                              fix_scan_list(glob, splan->scan.plan.targetlist, rtoffset);
                        splan->scan.plan.qual =
                              fix_scan_list(glob, splan->scan.plan.qual, rtoffset);
                        splan->funcexpr =
                              fix_scan_expr(glob, splan->funcexpr, rtoffset);
                  }
                  break;
            case T_ValuesScan:
                  {
                        ValuesScan *splan = (ValuesScan *) plan;

                        splan->scan.scanrelid += rtoffset;
                        splan->scan.plan.targetlist =
                              fix_scan_list(glob, splan->scan.plan.targetlist, rtoffset);
                        splan->scan.plan.qual =
                              fix_scan_list(glob, splan->scan.plan.qual, rtoffset);
                        splan->values_lists =
                              fix_scan_list(glob, splan->values_lists, rtoffset);
                  }
                  break;
            case T_CteScan:
                  {
                        CteScan    *splan = (CteScan *) plan;

                        splan->scan.scanrelid += rtoffset;
                        splan->scan.plan.targetlist =
                              fix_scan_list(glob, splan->scan.plan.targetlist, rtoffset);
                        splan->scan.plan.qual =
                              fix_scan_list(glob, splan->scan.plan.qual, rtoffset);
                  }
                  break;
            case T_WorkTableScan:
                  {
                        WorkTableScan *splan = (WorkTableScan *) plan;

                        splan->scan.scanrelid += rtoffset;
                        splan->scan.plan.targetlist =
                              fix_scan_list(glob, splan->scan.plan.targetlist, rtoffset);
                        splan->scan.plan.qual =
                              fix_scan_list(glob, splan->scan.plan.qual, rtoffset);
                  }
                  break;
            case T_NestLoop:
            case T_MergeJoin:
            case T_HashJoin:
                  set_join_references(glob, (Join *) plan, rtoffset);
                  break;

            case T_Hash:
            case T_Material:
            case T_Sort:
            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_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(glob, splan->limitOffset, rtoffset);
                        splan->limitCount =
                              fix_scan_expr(glob, splan->limitCount, rtoffset);
                  }
                  break;
            case T_Agg:
            case T_WindowAgg:
            case T_Group:
                  set_upper_references(glob, plan, rtoffset);
                  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(glob, plan, rtoffset);
                        else
                        {
                              splan->plan.targetlist =
                                    fix_scan_list(glob, splan->plan.targetlist, rtoffset);
                              splan->plan.qual =
                                    fix_scan_list(glob, splan->plan.qual, rtoffset);
                        }
                        /* resconstantqual can't contain any subplan variable refs */
                        splan->resconstantqual =
                              fix_scan_expr(glob, splan->resconstantqual, rtoffset);
                  }
                  break;
            case T_Append:
                  {
                        Append         *splan = (Append *) plan;

                        /*
                         * Append, like Sort et al, doesn't actually evaluate its
                         * targetlist or check quals.
                         */
                        set_dummy_tlist_references(plan, rtoffset);
                        Assert(splan->plan.qual == NIL);
                        foreach(l, splan->appendplans)
                        {
                              lfirst(l) = set_plan_refs(glob,
                                                                    (Plan *) lfirst(l),
                                                                    rtoffset);
                        }
                  }
                  break;
            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(glob,
                                                                    (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(glob,
                                                                    (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(glob, plan->lefttree, rtoffset);
      plan->righttree = set_plan_refs(glob, plan->righttree, rtoffset);

      return 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(PlannerGlobal *glob,
                                          SubqueryScan *plan,
                                          int rtoffset)
{
      Plan     *result;

      /* First, recursively process the subplan */
      plan->subplan = set_plan_references(glob, plan->subplan, plan->subrtable);

      /* subrtable is no longer needed in the plan tree */
      plan->subrtable = NIL;

      if (trivial_subqueryscan(plan))
      {
            /*
             * We can omit the SubqueryScan node and just pull up the subplan.
             */
            ListCell   *lp,
                           *lc;

            result = plan->subplan;

            /* We have to be sure we don't lose any initplans */
            result->initPlan = list_concat(plan->scan.plan.initPlan,
                                                         result->initPlan);

            /*
             * We also have to transfer the SubqueryScan's result-column names
             * into the subplan, else columns sent to client will be improperly
             * labeled if this is the topmost plan level.  Copy the "source
             * column" information too.
             */
            forboth(lp, plan->scan.plan.targetlist, lc, result->targetlist)
            {
                  TargetEntry *ptle = (TargetEntry *) lfirst(lp);
                  TargetEntry *ctle = (TargetEntry *) lfirst(lc);

                  ctle->resname = ptle->resname;
                  ctle->resorigtbl = ptle->resorigtbl;
                  ctle->resorigcol = ptle->resorigcol;
            }
      }
      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(glob, plan->scan.plan.targetlist, rtoffset);
            plan->scan.plan.qual =
                  fix_scan_list(glob, plan->scan.plan.qual, rtoffset);

            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.
 */
static bool
trivial_subqueryscan(SubqueryScan *plan)
{
      int               attrno;
      ListCell   *lp,
                     *lc;

      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++;
      }

      return true;
}

/*
 * 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 glob->relationOids,
 * and add catalog TIDs for user-defined functions into glob->invalItems.
 *
 * 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(PlannerGlobal *glob, Node *node)
{
      /* We assume callers won't call us on a NULL pointer */
      if (IsA(node, Aggref))
      {
            record_plan_function_dependency(glob,
                                                            ((Aggref *) node)->aggfnoid);
      }
      else if (IsA(node, WindowFunc))
      {
            record_plan_function_dependency(glob,
                                                            ((WindowFunc *) node)->winfnoid);
      }
      else if (IsA(node, FuncExpr))
      {
            record_plan_function_dependency(glob,
                                                            ((FuncExpr *) node)->funcid);
      }
      else if (IsA(node, OpExpr))
      {
            set_opfuncid((OpExpr *) node);
            record_plan_function_dependency(glob,
                                                            ((OpExpr *) node)->opfuncid);
      }
      else if (IsA(node, DistinctExpr))
      {
            set_opfuncid((OpExpr *) node);      /* rely on struct equivalence */
            record_plan_function_dependency(glob,
                                                            ((DistinctExpr *) node)->opfuncid);
      }
      else if (IsA(node, NullIfExpr))
      {
            set_opfuncid((OpExpr *) node);      /* rely on struct equivalence */
            record_plan_function_dependency(glob,
                                                            ((NullIfExpr *) node)->opfuncid);
      }
      else if (IsA(node, ScalarArrayOpExpr))
      {
            set_sa_opfuncid((ScalarArrayOpExpr *) node);
            record_plan_function_dependency(glob,
                                                       ((ScalarArrayOpExpr *) node)->opfuncid);
      }
      else if (IsA(node, ArrayCoerceExpr))
      {
            if (OidIsValid(((ArrayCoerceExpr *) node)->elemfuncid))
                  record_plan_function_dependency(glob,
                                                       ((ArrayCoerceExpr *) node)->elemfuncid);
      }
      else if (IsA(node, Const))
      {
            Const    *con = (Const *) node;

            /* Check for regclass reference */
            if (ISREGCLASSCONST(con))
                  glob->relationOids =
                        lappend_oid(glob->relationOids,
                                          DatumGetObjectId(con->constvalue));
      }
}

/*
 * fix_scan_expr
 *          Do set_plan_references processing on a scan-level expression
 *
 * This consists of incrementing all Vars' varnos by rtoffset,
 * looking up operator opcode info for OpExpr and related nodes,
 * and adding OIDs from regclass Const nodes into glob->relationOids.
 */
static Node *
fix_scan_expr(PlannerGlobal *glob, Node *node, int rtoffset)
{
      fix_scan_expr_context context;

      context.glob = glob;
      context.rtoffset = rtoffset;

      if (rtoffset != 0 || glob->lastPHId != 0)
      {
            return fix_scan_expr_mutator(node, &context);
      }
      else
      {
            /*
             * If rtoffset == 0, we don't need to change any Vars, and if there
             * are no placeholders anywhere 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 any Vars marked INNER, but in a nestloop inner
             * scan there could be OUTER Vars.  Leave them alone.
             */
            Assert(var->varno != INNER);
            if (var->varno > 0 && var->varno != OUTER)
                  var->varno += context->rtoffset;
            if (var->varnoold > 0)
                  var->varnoold += context->rtoffset;
            return (Node *) var;
      }
      if (IsA(node, CurrentOfExpr))
      {
            CurrentOfExpr *cexpr = (CurrentOfExpr *) copyObject(node);

            Assert(cexpr->cvarno != INNER);
            Assert(cexpr->cvarno != OUTER);
            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;

            return fix_scan_expr_mutator((Node *) phv->phexpr, context);
      }
      fix_expr_common(context->glob, node);
      return expression_tree_mutator(node, fix_scan_expr_mutator,
                                                   (void *) context);
}

static bool
fix_scan_expr_walker(Node *node, fix_scan_expr_context *context)
{
      if (node == NULL)
            return false;
      Assert(!IsA(node, PlaceHolderVar));
      fix_expr_common(context->glob, node);
      return expression_tree_walker(node, fix_scan_expr_walker,
                                                  (void *) context);
}

/*
 * set_join_references
 *      Modify the target list and quals of a join node to reference its
 *      subplans, by setting the varnos to OUTER or INNER 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 glob->relationOids.
 *
 * In the case of a nestloop with inner indexscan, we will also need to
 * apply the same transformation to any outer vars appearing in the
 * quals of the child indexscan.  set_inner_join_references does that.
 */
static void
set_join_references(PlannerGlobal *glob, 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);

      /* All join plans have tlist, qual, and joinqual */
      join->plan.targetlist = fix_join_expr(glob,
                                                              join->plan.targetlist,
                                                              outer_itlist,
                                                              inner_itlist,
                                                              (Index) 0,
                                                              rtoffset);
      join->plan.qual = fix_join_expr(glob,
                                                      join->plan.qual,
                                                      outer_itlist,
                                                      inner_itlist,
                                                      (Index) 0,
                                                      rtoffset);
      join->joinqual = fix_join_expr(glob,
                                                   join->joinqual,
                                                   outer_itlist,
                                                   inner_itlist,
                                                   (Index) 0,
                                                   rtoffset);

      /* Now do join-type-specific stuff */
      if (IsA(join, NestLoop))
      {
            /* This processing is split out to handle possible recursion */
            set_inner_join_references(glob, inner_plan, outer_itlist);
      }
      else if (IsA(join, MergeJoin))
      {
            MergeJoin  *mj = (MergeJoin *) join;

            mj->mergeclauses = fix_join_expr(glob,
                                                             mj->mergeclauses,
                                                             outer_itlist,
                                                             inner_itlist,
                                                             (Index) 0,
                                                             rtoffset);
      }
      else if (IsA(join, HashJoin))
      {
            HashJoin   *hj = (HashJoin *) join;

            hj->hashclauses = fix_join_expr(glob,
                                                            hj->hashclauses,
                                                            outer_itlist,
                                                            inner_itlist,
                                                            (Index) 0,
                                                            rtoffset);
      }

      pfree(outer_itlist);
      pfree(inner_itlist);
}

/*
 * set_inner_join_references
 *          Handle join references appearing in an inner indexscan's quals
 *
 * To handle bitmap-scan plan trees, we have to be able to recurse down
 * to the bottom BitmapIndexScan nodes; likewise, appendrel indexscans
 * require recursing through Append nodes.      This is split out as a separate
 * function so that it can recurse.
 *
 * Note we do *not* apply any rtoffset for non-join Vars; this is because
 * the quals will be processed again by fix_scan_expr when the set_plan_refs
 * recursion reaches the inner indexscan, and so we'd have done it twice.
 */
static void
set_inner_join_references(PlannerGlobal *glob, Plan *inner_plan,
                                      indexed_tlist *outer_itlist)
{
      if (IsA(inner_plan, IndexScan))
      {
            /*
             * An index is being used to reduce the number of tuples scanned in
             * the inner relation.  If there are join clauses being used with the
             * index, we must update their outer-rel var nodes to refer to the
             * outer side of the join.
             */
            IndexScan  *innerscan = (IndexScan *) inner_plan;
            List     *indexqualorig = innerscan->indexqualorig;

            /* No work needed if indexqual refers only to its own rel... */
            if (NumRelids((Node *) indexqualorig) > 1)
            {
                  Index       innerrel = innerscan->scan.scanrelid;

                  /* only refs to outer vars get changed in the inner qual */
                  innerscan->indexqualorig = fix_join_expr(glob,
                                                                               indexqualorig,
                                                                               outer_itlist,
                                                                               NULL,
                                                                               innerrel,
                                                                               0);
                  innerscan->indexqual = fix_join_expr(glob,
                                                                         innerscan->indexqual,
                                                                         outer_itlist,
                                                                         NULL,
                                                                         innerrel,
                                                                         0);

                  /*
                   * We must fix the inner qpqual too, if it has join clauses (this
                   * could happen if special operators are involved: some indexquals
                   * may get rechecked as qpquals).
                   */
                  if (NumRelids((Node *) inner_plan->qual) > 1)
                        inner_plan->qual = fix_join_expr(glob,
                                                                         inner_plan->qual,
                                                                         outer_itlist,
                                                                         NULL,
                                                                         innerrel,
                                                                         0);
            }
      }
      else if (IsA(inner_plan, BitmapIndexScan))
      {
            /*
             * Same, but index is being used within a bitmap plan.
             */
            BitmapIndexScan *innerscan = (BitmapIndexScan *) inner_plan;
            List     *indexqualorig = innerscan->indexqualorig;

            /* No work needed if indexqual refers only to its own rel... */
            if (NumRelids((Node *) indexqualorig) > 1)
            {
                  Index       innerrel = innerscan->scan.scanrelid;

                  /* only refs to outer vars get changed in the inner qual */
                  innerscan->indexqualorig = fix_join_expr(glob,
                                                                               indexqualorig,
                                                                               outer_itlist,
                                                                               NULL,
                                                                               innerrel,
                                                                               0);
                  innerscan->indexqual = fix_join_expr(glob,
                                                                         innerscan->indexqual,
                                                                         outer_itlist,
                                                                         NULL,
                                                                         innerrel,
                                                                         0);
                  /* no need to fix inner qpqual */
                  Assert(inner_plan->qual == NIL);
            }
      }
      else if (IsA(inner_plan, BitmapHeapScan))
      {
            /*
             * The inner side is a bitmap scan plan.  Fix the top node, and
             * recurse to get the lower nodes.
             *
             * Note: create_bitmap_scan_plan removes clauses from bitmapqualorig
             * if they are duplicated in qpqual, so must test these independently.
             */
            BitmapHeapScan *innerscan = (BitmapHeapScan *) inner_plan;
            Index       innerrel = innerscan->scan.scanrelid;
            List     *bitmapqualorig = innerscan->bitmapqualorig;

            /* only refs to outer vars get changed in the inner qual */
            if (NumRelids((Node *) bitmapqualorig) > 1)
                  innerscan->bitmapqualorig = fix_join_expr(glob,
                                                                                bitmapqualorig,
                                                                                outer_itlist,
                                                                                NULL,
                                                                                innerrel,
                                                                                0);

            /*
             * We must fix the inner qpqual too, if it has join clauses (this
             * could happen if special operators are involved: some indexquals may
             * get rechecked as qpquals).
             */
            if (NumRelids((Node *) inner_plan->qual) > 1)
                  inner_plan->qual = fix_join_expr(glob,
                                                                   inner_plan->qual,
                                                                   outer_itlist,
                                                                   NULL,
                                                                   innerrel,
                                                                   0);

            /* Now recurse */
            set_inner_join_references(glob, inner_plan->lefttree, outer_itlist);
      }
      else if (IsA(inner_plan, BitmapAnd))
      {
            /* All we need do here is recurse */
            BitmapAnd  *innerscan = (BitmapAnd *) inner_plan;
            ListCell   *l;

            foreach(l, innerscan->bitmapplans)
            {
                  set_inner_join_references(glob, (Plan *) lfirst(l), outer_itlist);
            }
      }
      else if (IsA(inner_plan, BitmapOr))
      {
            /* All we need do here is recurse */
            BitmapOr   *innerscan = (BitmapOr *) inner_plan;
            ListCell   *l;

            foreach(l, innerscan->bitmapplans)
            {
                  set_inner_join_references(glob, (Plan *) lfirst(l), outer_itlist);
            }
      }
      else if (IsA(inner_plan, TidScan))
      {
            TidScan    *innerscan = (TidScan *) inner_plan;
            Index       innerrel = innerscan->scan.scanrelid;

            innerscan->tidquals = fix_join_expr(glob,
                                                                  innerscan->tidquals,
                                                                  outer_itlist,
                                                                  NULL,
                                                                  innerrel,
                                                                  0);
      }
      else if (IsA(inner_plan, Append))
      {
            /*
             * The inner side is an append plan.  Recurse to see if it contains
             * indexscans that need to be fixed.
             */
            Append         *appendplan = (Append *) inner_plan;
            ListCell   *l;

            foreach(l, appendplan->appendplans)
            {
                  set_inner_join_references(glob, (Plan *) lfirst(l), outer_itlist);
            }
      }
      else if (IsA(inner_plan, Result))
      {
            /* Recurse through a gating Result node (similar to Append case) */
            Result         *result = (Result *) inner_plan;

            if (result->plan.lefttree)
                  set_inner_join_references(glob, result->plan.lefttree, outer_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 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 flatten_tlist() from these selfsame expressions, so it
 * should have all the required variables).  There is an important exception,
 * however: GROUP BY and ORDER BY expressions will 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(PlannerGlobal *glob, Plan *plan, int rtoffset)
{
      Plan     *subplan = plan->lefttree;
      indexed_tlist *subplan_itlist;
      List     *output_targetlist;
      ListCell   *l;

      subplan_itlist = build_tlist_index(subplan->targetlist);

      output_targetlist = NIL;
      foreach(l, plan->targetlist)
      {
            TargetEntry *tle = (TargetEntry *) lfirst(l);
            Node     *newexpr;

            /* If it's a non-Var sort/group item, first try to match by sortref */
            if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
            {
                  newexpr = (Node *)
                        search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
                                                                                tle->ressortgroupref,
                                                                                subplan_itlist,
                                                                                OUTER);
                  if (!newexpr)
                        newexpr = fix_upper_expr(glob,
                                                             (Node *) tle->expr,
                                                             subplan_itlist,
                                                             rtoffset);
            }
            else
                  newexpr = fix_upper_expr(glob,
                                                       (Node *) tle->expr,
                                                       subplan_itlist,
                                                       rtoffset);
            tle = flatCopyTargetEntry(tle);
            tle->expr = (Expr *) newexpr;
            output_targetlist = lappend(output_targetlist, tle);
      }
      plan->targetlist = output_targetlist;

      plan->qual = (List *)
            fix_upper_expr(glob,
                                 (Node *) plan->qual,
                                 subplan_itlist,
                                 rtoffset);

      pfree(subplan_itlist);
}

/*
 * set_dummy_tlist_references
 *      Replace the targetlist of an upper-level plan node with a simple
 *      list of OUTER 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;

            newvar = makeVar(OUTER,
                                     tle->resno,
                                     exprType((Node *) oldvar),
                                     exprTypmod((Node *) oldvar),
                                     0);
            if (IsA(oldvar, Var))
            {
                  newvar->varnoold = oldvar->varno + rtoffset;
                  newvar->varoattno = oldvar->varattno;
            }
            else
            {
                  newvar->varnoold = 0;         /* wasn't ever a plain Var */
                  newvar->varoattno = 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() or search_indexed_tlist_for_non_var().
 * 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++;
            }
            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, Index 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++;
                  }
            }
            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 varnoold is incremented by rtoffset.
 * If no match, return NULL.
 */
static Var *
search_indexed_tlist_for_var(Var *var, indexed_tlist *itlist,
                                           Index newvarno, int rtoffset)
{
      Index       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);

                  newvar->varno = newvarno;
                  newvar->varattno = vinfo->resno;
                  if (newvar->varnoold > 0)
                        newvar->varnoold += rtoffset;
                  return newvar;
            }
            vinfo++;
      }
      return NULL;                        /* no match */
}

/*
 * search_indexed_tlist_for_non_var --- find a non-Var 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_ph_vars or
 * itlist->has_non_vars
 */
static Var *
search_indexed_tlist_for_non_var(Node *node,
                                                 indexed_tlist *itlist, Index newvarno)
{
      TargetEntry *tle;

      tle = tlist_member(node, itlist->tlist);
      if (tle)
      {
            /* Found a matching subplan output expression */
            Var            *newvar;

            newvar = makeVar(newvarno,
                                     tle->resno,
                                     exprType((Node *) tle->expr),
                                     exprTypmod((Node *) tle->expr),
                                     0);
            newvar->varnoold = 0;   /* wasn't ever a plain Var */
            newvar->varoattno = 0;
            return newvar;
      }
      return NULL;                        /* no match */
}

/*
 * search_indexed_tlist_for_sortgroupref --- find a sort/group expression
 *          (which is assumed not to be just a Var)
 *
 * 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(Node *node,
                                                        Index sortgroupref,
                                                        indexed_tlist *itlist,
                                                        Index newvarno)
{
      ListCell   *lc;

      foreach(lc, itlist->tlist)
      {
            TargetEntry *tle = (TargetEntry *) lfirst(lc);

            /* The equal() check should be redundant, but let's be paranoid */
            if (tle->ressortgroupref == sortgroupref &&
                  equal(node, tle->expr))
            {
                  /* Found a matching subplan output expression */
                  Var            *newvar;

                  newvar = makeVar(newvarno,
                                           tle->resno,
                                           exprType((Node *) tle->expr),
                                           exprTypmod((Node *) tle->expr),
                                           0);
                  newvar->varnoold = 0;   /* wasn't ever a plain Var */
                  newvar->varoattno = 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 glob->relationOids.
 *
 * This is used in two different scenarios: a normal join clause, where
 * all the Vars in the clause *must* be replaced by OUTER or INNER references;
 * and an indexscan being used on the inner side of a nestloop join.
 * In the latter case we want to replace the outer-relation Vars by OUTER
 * references, while Vars of the inner relation should be adjusted by rtoffset.
 * (We also implement RETURNING clause fixup using this second scenario.)
 *
 * For a normal join, acceptable_rel should be zero so that any failure to
 * match a Var will be reported as an error.  For the indexscan case,
 * pass inner_itlist = NULL and acceptable_rel = the (not-offseted-yet) ID
 * of the inner relation.
 *
 * 'clauses' is the targetlist or list of join clauses
 * 'outer_itlist' is the indexed target list of the outer join relation
 * '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' is what to add to varno for Vars of acceptable_rel.
 *
 * Returns the new expression tree.  The original clause structure is
 * not modified.
 */
static List *
fix_join_expr(PlannerGlobal *glob,
                    List *clauses,
                    indexed_tlist *outer_itlist,
                    indexed_tlist *inner_itlist,
                    Index acceptable_rel,
                    int rtoffset)
{
      fix_join_expr_context context;

      context.glob = glob;
      context.outer_itlist = outer_itlist;
      context.inner_itlist = inner_itlist;
      context.acceptable_rel = acceptable_rel;
      context.rtoffset = rtoffset;
      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;

            /* First look for the var in the input tlists */
            newvar = search_indexed_tlist_for_var(var,
                                                                    context->outer_itlist,
                                                                    OUTER,
                                                                    context->rtoffset);
            if (newvar)
                  return (Node *) newvar;
            if (context->inner_itlist)
            {
                  newvar = search_indexed_tlist_for_var(var,
                                                                          context->inner_itlist,
                                                                          INNER,
                                                                          context->rtoffset);
                  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;
                  var->varnoold += 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->has_ph_vars)
            {
                  newvar = search_indexed_tlist_for_non_var((Node *) phv,
                                                                                context->outer_itlist,
                                                                                OUTER);
                  if (newvar)
                        return (Node *) newvar;
            }
            if (context->inner_itlist && context->inner_itlist->has_ph_vars)
            {
                  newvar = search_indexed_tlist_for_non_var((Node *) phv,
                                                                                context->inner_itlist,
                                                                                INNER);
                  if (newvar)
                        return (Node *) newvar;
            }

            /* If not supplied by input plans, evaluate the contained expr */
            return fix_join_expr_mutator((Node *) phv->phexpr, context);
      }
      /* Try matching more complex expressions too, if tlists have any */
      if (context->outer_itlist->has_non_vars)
      {
            newvar = search_indexed_tlist_for_non_var(node,
                                                                          context->outer_itlist,
                                                                          OUTER);
            if (newvar)
                  return (Node *) newvar;
      }
      if (context->inner_itlist && context->inner_itlist->has_non_vars)
      {
            newvar = search_indexed_tlist_for_non_var(node,
                                                                          context->inner_itlist,
                                                                          INNER);
            if (newvar)
                  return (Node *) newvar;
      }
      fix_expr_common(context->glob, node);
      return expression_tree_mutator(node,
                                                   fix_join_expr_mutator,
                                                   (void *) context);
}

/*
 * fix_upper_expr
 *          Modifies an expression tree so that all Var nodes reference outputs
 *          of a subplan.  Also performs opcode lookup, and adds regclass OIDs to
 *          glob->relationOids.
 *
 * This is used to fix up target and qual expressions of non-join upper-level
 * plan 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 via flatten_tlist() or some such method.
 *
 * 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
 * 'rtoffset': how much to increment varnoold by
 *
 * The resulting tree is a copy of the original in which all Var nodes have
 * varno = OUTER, varattno = resno of corresponding subplan target.
 * The original tree is not modified.
 */
static Node *
fix_upper_expr(PlannerGlobal *glob,
                     Node *node,
                     indexed_tlist *subplan_itlist,
                     int rtoffset)
{
      fix_upper_expr_context context;

      context.glob = glob;
      context.subplan_itlist = subplan_itlist;
      context.rtoffset = rtoffset;
      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,
                                                                    OUTER,
                                                                    context->rtoffset);
            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_non_var((Node *) phv,
                                                                                context->subplan_itlist,
                                                                                OUTER);
                  if (newvar)
                        return (Node *) newvar;
            }
            /* If not supplied by input plan, evaluate the contained expr */
            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(node,
                                                                          context->subplan_itlist,
                                                                          OUTER);
            if (newvar)
                  return (Node *) newvar;
      }
      fix_expr_common(context->glob, node);
      return expression_tree_mutator(node,
                                                   fix_upper_expr_mutator,
                                                   (void *) 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 plan'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 still have their
 * original varno, but Vars for other rels will have varno OUTER.
 *
 * We also must perform opcode lookup and add regclass OIDs to
 * glob->relationOids.
 *
 * 'rlist': the RETURNING targetlist to be fixed
 * 'topplan': the top Plan node for the query (not yet passed through
 *          set_plan_references)
 * 'resultRelation': RT index of the associated result relation
 *
 * Note: we assume that result relations will have rtoffset zero, that is,
 * they are not coming from a subplan.
 */
List *
set_returning_clause_references(PlannerGlobal *glob,
                                                List *rlist,
                                                Plan *topplan,
                                                Index resultRelation)
{
      indexed_tlist *itlist;

      /*
       * We can perform the desired Var fixup by abusing the fix_join_expr
       * machinery that normally handles 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(glob,
                                      rlist,
                                      itlist,
                                      NULL,
                                      resultRelation,
                                      0);

      pfree(itlist);

      return rlist;
}

/*****************************************************************************
 *                            OPERATOR REGPROC LOOKUP
 *****************************************************************************/

/*
 * fix_opfuncids
 *      Calculate opfuncid field from opno for each OpExpr node in given tree.
 *      The given tree can be anything expression_tree_walker handles.
 *
 * The argument is modified in-place.  (This is OK since we'd want the
 * same change for any node, even if it gets visited more than once due to
 * shared structure.)
 */
void
fix_opfuncids(Node *node)
{
      /* This tree walk requires no special setup, so away we go... */
      fix_opfuncids_walker(node, NULL);
}

static bool
fix_opfuncids_walker(Node *node, void *context)
{
      if (node == NULL)
            return false;
      if (IsA(node, OpExpr))
            set_opfuncid((OpExpr *) node);
      else if (IsA(node, DistinctExpr))
            set_opfuncid((OpExpr *) node);      /* rely on struct equivalence */
      else if (IsA(node, NullIfExpr))
            set_opfuncid((OpExpr *) node);      /* rely on struct equivalence */
      else if (IsA(node, ScalarArrayOpExpr))
            set_sa_opfuncid((ScalarArrayOpExpr *) node);
      return expression_tree_walker(node, fix_opfuncids_walker, context);
}

/*
 * set_opfuncid
 *          Set the opfuncid (procedure OID) in an OpExpr node,
 *          if it hasn't been set already.
 *
 * Because of struct equivalence, this can also be used for
 * DistinctExpr and NullIfExpr nodes.
 */
void
set_opfuncid(OpExpr *opexpr)
{
      if (opexpr->opfuncid == InvalidOid)
            opexpr->opfuncid = get_opcode(opexpr->opno);
}

/*
 * set_sa_opfuncid
 *          As above, for ScalarArrayOpExpr nodes.
 */
void
set_sa_opfuncid(ScalarArrayOpExpr *opexpr)
{
      if (opexpr->opfuncid == InvalidOid)
            opexpr->opfuncid = get_opcode(opexpr->opno);
}

/*****************************************************************************
 *                            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(PlannerGlobal *glob, 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 FirstBootstrapObjectId.
       * Note that the OID generator guarantees never to generate such an OID
       * after startup, even at OID wraparound.
       */
      if (funcid >= (Oid) FirstBootstrapObjectId)
      {
            HeapTuple   func_tuple;
            PlanInvalItem *inval_item;

            func_tuple = SearchSysCache(PROCOID,
                                                      ObjectIdGetDatum(funcid),
                                                      0, 0, 0);
            if (!HeapTupleIsValid(func_tuple))
                  elog(ERROR, "cache lookup failed for function %u", funcid);

            inval_item = makeNode(PlanInvalItem);

            /*
             * It would work to use any syscache on pg_proc, but plancache.c
             * expects us to use PROCOID.
             */
            inval_item->cacheId = PROCOID;
            inval_item->tupleId = func_tuple->t_self;

            glob->invalItems = lappend(glob->invalItems, inval_item);

            ReleaseSysCache(func_tuple);
      }
}

/*
 * extract_query_dependencies
 *          Given a list of not-yet-planned queries (i.e. Query nodes),
 *          extract their dependencies just as set_plan_references would do.
 *
 * This is needed by plancache.c to handle invalidation of cached unplanned
 * queries.
 */
void
extract_query_dependencies(List *queries,
                                       List **relationOids,
                                       List **invalItems)
{
      PlannerGlobal glob;

      /* Make up a dummy PlannerGlobal so we can use this module's machinery */
      MemSet(&glob, 0, sizeof(glob));
      glob.type = T_PlannerGlobal;
      glob.relationOids = NIL;
      glob.invalItems = NIL;

      (void) extract_query_dependencies_walker((Node *) queries, &glob);

      *relationOids = glob.relationOids;
      *invalItems = glob.invalItems;
}

static bool
extract_query_dependencies_walker(Node *node, PlannerGlobal *context)
{
      if (node == NULL)
            return false;
      Assert(!IsA(node, PlaceHolderVar));
      /* Extract function dependencies and check for regclass Consts */
      fix_expr_common(context, node);
      if (IsA(node, Query))
      {
            Query    *query = (Query *) node;
            ListCell   *lc;

            /* Collect relation OIDs in this Query's rtable */
            foreach(lc, query->rtable)
            {
                  RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);

                  if (rte->rtekind == RTE_RELATION)
                        context->relationOids = lappend_oid(context->relationOids,
                                                                              rte->relid);
            }

            /* And recurse into the query's subexpressions */
            return query_tree_walker(query, extract_query_dependencies_walker,
                                                 (void *) context, 0);
      }
      return expression_tree_walker(node, extract_query_dependencies_walker,
                                                  (void *) context);
}

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