Adding upstream version 15.5.upstream/15.5

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3746 insertions, 0 deletions

diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
new file mode 100644
index 0000000..7f4bb7b
--- /dev/null
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -0,0 +1,3746 @@
+/*-------------------------------------------------------------------------
+ *
+ * prepjointree.c
+ *	  Planner preprocessing for subqueries and join tree manipulation.
+ *
+ * NOTE: the intended sequence for invoking these operations is
+ *		replace_empty_jointree
+ *		pull_up_sublinks
+ *		preprocess_function_rtes
+ *		pull_up_subqueries
+ *		flatten_simple_union_all
+ *		do expression preprocessing (including flattening JOIN alias vars)
+ *		reduce_outer_joins
+ *		remove_useless_result_rtes
+ *
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/optimizer/prep/prepjointree.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "catalog/pg_type.h"
+#include "funcapi.h"
+#include "miscadmin.h"
+#include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
+#include "optimizer/clauses.h"
+#include "optimizer/optimizer.h"
+#include "optimizer/placeholder.h"
+#include "optimizer/prep.h"
+#include "optimizer/subselect.h"
+#include "optimizer/tlist.h"
+#include "parser/parse_relation.h"
+#include "parser/parsetree.h"
+#include "rewrite/rewriteManip.h"
+
+
+typedef struct pullup_replace_vars_context
+{
+	PlannerInfo *root;
+	List	   *targetlist;		/* tlist of subquery being pulled up */
+	RangeTblEntry *target_rte;	/* RTE of subquery */
+	Relids		relids;			/* relids within subquery, as numbered after
+								 * pullup (set only if target_rte->lateral) */
+	bool	   *outer_hasSubLinks;	/* -> outer query's hasSubLinks */
+	int			varno;			/* varno of subquery */
+	bool		need_phvs;		/* do we need PlaceHolderVars? */
+	bool		wrap_non_vars;	/* do we need 'em on *all* non-Vars? */
+	Node	  **rv_cache;		/* cache for results with PHVs */
+} pullup_replace_vars_context;
+
+typedef struct reduce_outer_joins_state
+{
+	Relids		relids;			/* base relids within this subtree */
+	bool		contains_outer; /* does subtree contain outer join(s)? */
+	List	   *sub_states;		/* List of states for subtree components */
+} reduce_outer_joins_state;
+
+static Node *pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode,
+											   Relids *relids);
+static Node *pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
+										   Node **jtlink1, Relids available_rels1,
+										   Node **jtlink2, Relids available_rels2);
+static Node *pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
+										JoinExpr *lowest_outer_join,
+										JoinExpr *lowest_nulling_outer_join,
+										AppendRelInfo *containing_appendrel);
+static Node *pull_up_simple_subquery(PlannerInfo *root, Node *jtnode,
+									 RangeTblEntry *rte,
+									 JoinExpr *lowest_outer_join,
+									 JoinExpr *lowest_nulling_outer_join,
+									 AppendRelInfo *containing_appendrel);
+static Node *pull_up_simple_union_all(PlannerInfo *root, Node *jtnode,
+									  RangeTblEntry *rte);
+static void pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root,
+									   int parentRTindex, Query *setOpQuery,
+									   int childRToffset);
+static void make_setop_translation_list(Query *query, int newvarno,
+										AppendRelInfo *appinfo);
+static bool is_simple_subquery(PlannerInfo *root, Query *subquery,
+							   RangeTblEntry *rte,
+							   JoinExpr *lowest_outer_join);
+static Node *pull_up_simple_values(PlannerInfo *root, Node *jtnode,
+								   RangeTblEntry *rte);
+static bool is_simple_values(PlannerInfo *root, RangeTblEntry *rte);
+static Node *pull_up_constant_function(PlannerInfo *root, Node *jtnode,
+									   RangeTblEntry *rte,
+									   JoinExpr *lowest_nulling_outer_join,
+									   AppendRelInfo *containing_appendrel);
+static bool is_simple_union_all(Query *subquery);
+static bool is_simple_union_all_recurse(Node *setOp, Query *setOpQuery,
+										List *colTypes);
+static bool is_safe_append_member(Query *subquery);
+static bool jointree_contains_lateral_outer_refs(PlannerInfo *root,
+												 Node *jtnode, bool restricted,
+												 Relids safe_upper_varnos);
+static void perform_pullup_replace_vars(PlannerInfo *root,
+										pullup_replace_vars_context *rvcontext,
+										JoinExpr *lowest_nulling_outer_join,
+										AppendRelInfo *containing_appendrel);
+static void replace_vars_in_jointree(Node *jtnode,
+									 pullup_replace_vars_context *context,
+									 JoinExpr *lowest_nulling_outer_join);
+static Node *pullup_replace_vars(Node *expr,
+								 pullup_replace_vars_context *context);
+static Node *pullup_replace_vars_callback(Var *var,
+										  replace_rte_variables_context *context);
+static Query *pullup_replace_vars_subquery(Query *query,
+										   pullup_replace_vars_context *context);
+static reduce_outer_joins_state *reduce_outer_joins_pass1(Node *jtnode);
+static void reduce_outer_joins_pass2(Node *jtnode,
+									 reduce_outer_joins_state *state,
+									 PlannerInfo *root,
+									 Relids nonnullable_rels,
+									 List *nonnullable_vars,
+									 List *forced_null_vars);
+static Node *remove_useless_results_recurse(PlannerInfo *root, Node *jtnode);
+static int	get_result_relid(PlannerInfo *root, Node *jtnode);
+static void remove_result_refs(PlannerInfo *root, int varno, Node *newjtloc);
+static bool find_dependent_phvs(PlannerInfo *root, int varno);
+static bool find_dependent_phvs_in_jointree(PlannerInfo *root,
+											Node *node, int varno);
+static void substitute_phv_relids(Node *node,
+								  int varno, Relids subrelids);
+static void fix_append_rel_relids(List *append_rel_list, int varno,
+								  Relids subrelids);
+static Node *find_jointree_node_for_rel(Node *jtnode, int relid);
+
+
+/*
+ * transform_MERGE_to_join
+ *		Replace a MERGE's jointree to also include the target relation.
+ */
+void
+transform_MERGE_to_join(Query *parse)
+{
+	RangeTblEntry *joinrte;
+	JoinExpr   *joinexpr;
+	JoinType	jointype;
+	int			joinrti;
+	List	   *vars;
+
+	if (parse->commandType != CMD_MERGE)
+		return;
+
+	/* XXX probably bogus */
+	vars = NIL;
+
+	/*
+	 * When any WHEN NOT MATCHED THEN INSERT clauses exist, we need to use an
+	 * outer join so that we process all unmatched tuples from the source
+	 * relation.  If none exist, we can use an inner join.
+	 */
+	if (parse->mergeUseOuterJoin)
+		jointype = JOIN_RIGHT;
+	else
+		jointype = JOIN_INNER;
+
+	/* Manufacture a join RTE to use. */
+	joinrte = makeNode(RangeTblEntry);
+	joinrte->rtekind = RTE_JOIN;
+	joinrte->jointype = jointype;
+	joinrte->joinmergedcols = 0;
+	joinrte->joinaliasvars = vars;
+	joinrte->joinleftcols = NIL;	/* MERGE does not allow JOIN USING */
+	joinrte->joinrightcols = NIL;	/* ditto */
+	joinrte->join_using_alias = NULL;
+
+	joinrte->alias = NULL;
+	joinrte->eref = makeAlias("*MERGE*", NIL);
+	joinrte->lateral = false;
+	joinrte->inh = false;
+	joinrte->inFromCl = true;
+	joinrte->requiredPerms = 0;
+	joinrte->checkAsUser = InvalidOid;
+	joinrte->selectedCols = NULL;
+	joinrte->insertedCols = NULL;
+	joinrte->updatedCols = NULL;
+	joinrte->extraUpdatedCols = NULL;
+	joinrte->securityQuals = NIL;
+
+	/*
+	 * Add completed RTE to pstate's range table list, so that we know its
+	 * index.
+	 */
+	parse->rtable = lappend(parse->rtable, joinrte);
+	joinrti = list_length(parse->rtable);
+
+	/*
+	 * Create a JOIN between the target and the source relation.
+	 */
+	joinexpr = makeNode(JoinExpr);
+	joinexpr->jointype = jointype;
+	joinexpr->isNatural = false;
+	joinexpr->larg = (Node *) makeNode(RangeTblRef);
+	((RangeTblRef *) joinexpr->larg)->rtindex = parse->resultRelation;
+	joinexpr->rarg = linitial(parse->jointree->fromlist);	/* original join */
+	joinexpr->usingClause = NIL;
+	joinexpr->join_using_alias = NULL;
+	/* The quals are removed from the jointree and into this specific join */
+	joinexpr->quals = parse->jointree->quals;
+	joinexpr->alias = NULL;
+	joinexpr->rtindex = joinrti;
+
+	/* Make the new join be the sole entry in the query's jointree */
+	parse->jointree->fromlist = list_make1(joinexpr);
+	parse->jointree->quals = NULL;
+}
+
+/*
+ * replace_empty_jointree
+ *		If the Query's jointree is empty, replace it with a dummy RTE_RESULT
+ *		relation.
+ *
+ * By doing this, we can avoid a bunch of corner cases that formerly existed
+ * for SELECTs with omitted FROM clauses.  An example is that a subquery
+ * with empty jointree previously could not be pulled up, because that would
+ * have resulted in an empty relid set, making the subquery not uniquely
+ * identifiable for join or PlaceHolderVar processing.
+ *
+ * Unlike most other functions in this file, this function doesn't recurse;
+ * we rely on other processing to invoke it on sub-queries at suitable times.
+ */
+void
+replace_empty_jointree(Query *parse)
+{
+	RangeTblEntry *rte;
+	Index		rti;
+	RangeTblRef *rtr;
+
+	/* Nothing to do if jointree is already nonempty */
+	if (parse->jointree->fromlist != NIL)
+		return;
+
+	/* We mustn't change it in the top level of a setop tree, either */
+	if (parse->setOperations)
+		return;
+
+	/* Create suitable RTE */
+	rte = makeNode(RangeTblEntry);
+	rte->rtekind = RTE_RESULT;
+	rte->eref = makeAlias("*RESULT*", NIL);
+
+	/* Add it to rangetable */
+	parse->rtable = lappend(parse->rtable, rte);
+	rti = list_length(parse->rtable);
+
+	/* And jam a reference into the jointree */
+	rtr = makeNode(RangeTblRef);
+	rtr->rtindex = rti;
+	parse->jointree->fromlist = list_make1(rtr);
+}
+
+/*
+ * pull_up_sublinks
+ *		Attempt to pull up ANY and EXISTS SubLinks to be treated as
+ *		semijoins or anti-semijoins.
+ *
+ * A clause "foo op ANY (sub-SELECT)" can be processed by pulling the
+ * sub-SELECT up to become a rangetable entry and treating the implied
+ * comparisons as quals of a semijoin.  However, this optimization *only*
+ * works at the top level of WHERE or a JOIN/ON clause, because we cannot
+ * distinguish whether the ANY ought to return FALSE or NULL in cases
+ * involving NULL inputs.  Also, in an outer join's ON clause we can only
+ * do this if the sublink is degenerate (ie, references only the nullable
+ * side of the join).  In that case it is legal to push the semijoin
+ * down into the nullable side of the join.  If the sublink references any
+ * nonnullable-side variables then it would have to be evaluated as part
+ * of the outer join, which makes things way too complicated.
+ *
+ * Under similar conditions, EXISTS and NOT EXISTS clauses can be handled
+ * by pulling up the sub-SELECT and creating a semijoin or anti-semijoin.
+ *
+ * This routine searches for such clauses and does the necessary parsetree
+ * transformations if any are found.
+ *
+ * This routine has to run before preprocess_expression(), so the quals
+ * clauses are not yet reduced to implicit-AND format, and are not guaranteed
+ * to be AND/OR-flat either.  That means we need to recursively search through
+ * explicit AND clauses.  We stop as soon as we hit a non-AND item.
+ */
+void
+pull_up_sublinks(PlannerInfo *root)
+{
+	Node	   *jtnode;
+	Relids		relids;
+
+	/* Begin recursion through the jointree */
+	jtnode = pull_up_sublinks_jointree_recurse(root,
+											   (Node *) root->parse->jointree,
+											   &relids);
+
+	/*
+	 * root->parse->jointree must always be a FromExpr, so insert a dummy one
+	 * if we got a bare RangeTblRef or JoinExpr out of the recursion.
+	 */
+	if (IsA(jtnode, FromExpr))
+		root->parse->jointree = (FromExpr *) jtnode;
+	else
+		root->parse->jointree = makeFromExpr(list_make1(jtnode), NULL);
+}
+
+/*
+ * Recurse through jointree nodes for pull_up_sublinks()
+ *
+ * In addition to returning the possibly-modified jointree node, we return
+ * a relids set of the contained rels into *relids.
+ */
+static Node *
+pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode,
+								  Relids *relids)
+{
+	/* Since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
+	if (jtnode == NULL)
+	{
+		*relids = NULL;
+	}
+	else if (IsA(jtnode, RangeTblRef))
+	{
+		int			varno = ((RangeTblRef *) jtnode)->rtindex;
+
+		*relids = bms_make_singleton(varno);
+		/* jtnode is returned unmodified */
+	}
+	else if (IsA(jtnode, FromExpr))
+	{
+		FromExpr   *f = (FromExpr *) jtnode;
+		List	   *newfromlist = NIL;
+		Relids		frelids = NULL;
+		FromExpr   *newf;
+		Node	   *jtlink;
+		ListCell   *l;
+
+		/* First, recurse to process children and collect their relids */
+		foreach(l, f->fromlist)
+		{
+			Node	   *newchild;
+			Relids		childrelids;
+
+			newchild = pull_up_sublinks_jointree_recurse(root,
+														 lfirst(l),
+														 &childrelids);
+			newfromlist = lappend(newfromlist, newchild);
+			frelids = bms_join(frelids, childrelids);
+		}
+		/* Build the replacement FromExpr; no quals yet */
+		newf = makeFromExpr(newfromlist, NULL);
+		/* Set up a link representing the rebuilt jointree */
+		jtlink = (Node *) newf;
+		/* Now process qual --- all children are available for use */
+		newf->quals = pull_up_sublinks_qual_recurse(root, f->quals,
+													&jtlink, frelids,
+													NULL, NULL);
+
+		/*
+		 * Note that the result will be either newf, or a stack of JoinExprs
+		 * with newf at the base.  We rely on subsequent optimization steps to
+		 * flatten this and rearrange the joins as needed.
+		 *
+		 * Although we could include the pulled-up subqueries in the returned
+		 * relids, there's no need since upper quals couldn't refer to their
+		 * outputs anyway.
+		 */
+		*relids = frelids;
+		jtnode = jtlink;
+	}
+	else if (IsA(jtnode, JoinExpr))
+	{
+		JoinExpr   *j;
+		Relids		leftrelids;
+		Relids		rightrelids;
+		Node	   *jtlink;
+
+		/*
+		 * Make a modifiable copy of join node, but don't bother copying its
+		 * subnodes (yet).
+		 */
+		j = (JoinExpr *) palloc(sizeof(JoinExpr));
+		memcpy(j, jtnode, sizeof(JoinExpr));
+		jtlink = (Node *) j;
+
+		/* Recurse to process children and collect their relids */
+		j->larg = pull_up_sublinks_jointree_recurse(root, j->larg,
+													&leftrelids);
+		j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg,
+													&rightrelids);
+
+		/*
+		 * Now process qual, showing appropriate child relids as available,
+		 * and attach any pulled-up jointree items at the right place. In the
+		 * inner-join case we put new JoinExprs above the existing one (much
+		 * as for a FromExpr-style join).  In outer-join cases the new
+		 * JoinExprs must go into the nullable side of the outer join. The
+		 * point of the available_rels machinations is to ensure that we only
+		 * pull up quals for which that's okay.
+		 *
+		 * We don't expect to see any pre-existing JOIN_SEMI or JOIN_ANTI
+		 * nodes here.
+		 */
+		switch (j->jointype)
+		{
+			case JOIN_INNER:
+				j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
+														 &jtlink,
+														 bms_union(leftrelids,
+																   rightrelids),
+														 NULL, NULL);
+				break;
+			case JOIN_LEFT:
+				j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
+														 &j->rarg,
+														 rightrelids,
+														 NULL, NULL);
+				break;
+			case JOIN_FULL:
+				/* can't do anything with full-join quals */
+				break;
+			case JOIN_RIGHT:
+				j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
+														 &j->larg,
+														 leftrelids,
+														 NULL, NULL);
+				break;
+			default:
+				elog(ERROR, "unrecognized join type: %d",
+					 (int) j->jointype);
+				break;
+		}
+
+		/*
+		 * Although we could include the pulled-up subqueries in the returned
+		 * relids, there's no need since upper quals couldn't refer to their
+		 * outputs anyway.  But we *do* need to include the join's own rtindex
+		 * because we haven't yet collapsed join alias variables, so upper
+		 * levels would mistakenly think they couldn't use references to this
+		 * join.
+		 */
+		*relids = bms_join(leftrelids, rightrelids);
+		if (j->rtindex)
+			*relids = bms_add_member(*relids, j->rtindex);
+		jtnode = jtlink;
+	}
+	else
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(jtnode));
+	return jtnode;
+}
+
+/*
+ * Recurse through top-level qual nodes for pull_up_sublinks()
+ *
+ * jtlink1 points to the link in the jointree where any new JoinExprs should
+ * be inserted if they reference available_rels1 (i.e., available_rels1
+ * denotes the relations present underneath jtlink1).  Optionally, jtlink2 can
+ * point to a second link where new JoinExprs should be inserted if they
+ * reference available_rels2 (pass NULL for both those arguments if not used).
+ * Note that SubLinks referencing both sets of variables cannot be optimized.
+ * If we find multiple pull-up-able SubLinks, they'll get stacked onto jtlink1
+ * and/or jtlink2 in the order we encounter them.  We rely on subsequent
+ * optimization to rearrange the stack if appropriate.
+ *
+ * Returns the replacement qual node, or NULL if the qual should be removed.
+ */
+static Node *
+pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
+							  Node **jtlink1, Relids available_rels1,
+							  Node **jtlink2, Relids available_rels2)
+{
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, SubLink))
+	{
+		SubLink    *sublink = (SubLink *) node;
+		JoinExpr   *j;
+		Relids		child_rels;
+
+		/* Is it a convertible ANY or EXISTS clause? */
+		if (sublink->subLinkType == ANY_SUBLINK)
+		{
+			if ((j = convert_ANY_sublink_to_join(root, sublink,
+												 available_rels1)) != NULL)
+			{
+				/* Yes; insert the new join node into the join tree */
+				j->larg = *jtlink1;
+				*jtlink1 = (Node *) j;
+				/* Recursively process pulled-up jointree nodes */
+				j->rarg = pull_up_sublinks_jointree_recurse(root,
+															j->rarg,
+															&child_rels);
+
+				/*
+				 * Now recursively process the pulled-up quals.  Any inserted
+				 * joins can get stacked onto either j->larg or j->rarg,
+				 * depending on which rels they reference.
+				 */
+				j->quals = pull_up_sublinks_qual_recurse(root,
+														 j->quals,
+														 &j->larg,
+														 available_rels1,
+														 &j->rarg,
+														 child_rels);
+				/* Return NULL representing constant TRUE */
+				return NULL;
+			}
+			if (available_rels2 != NULL &&
+				(j = convert_ANY_sublink_to_join(root, sublink,
+												 available_rels2)) != NULL)
+			{
+				/* Yes; insert the new join node into the join tree */
+				j->larg = *jtlink2;
+				*jtlink2 = (Node *) j;
+				/* Recursively process pulled-up jointree nodes */
+				j->rarg = pull_up_sublinks_jointree_recurse(root,
+															j->rarg,
+															&child_rels);
+
+				/*
+				 * Now recursively process the pulled-up quals.  Any inserted
+				 * joins can get stacked onto either j->larg or j->rarg,
+				 * depending on which rels they reference.
+				 */
+				j->quals = pull_up_sublinks_qual_recurse(root,
+														 j->quals,
+														 &j->larg,
+														 available_rels2,
+														 &j->rarg,
+														 child_rels);
+				/* Return NULL representing constant TRUE */
+				return NULL;
+			}
+		}
+		else if (sublink->subLinkType == EXISTS_SUBLINK)
+		{
+			if ((j = convert_EXISTS_sublink_to_join(root, sublink, false,
+													available_rels1)) != NULL)
+			{
+				/* Yes; insert the new join node into the join tree */
+				j->larg = *jtlink1;
+				*jtlink1 = (Node *) j;
+				/* Recursively process pulled-up jointree nodes */
+				j->rarg = pull_up_sublinks_jointree_recurse(root,
+															j->rarg,
+															&child_rels);
+
+				/*
+				 * Now recursively process the pulled-up quals.  Any inserted
+				 * joins can get stacked onto either j->larg or j->rarg,
+				 * depending on which rels they reference.
+				 */
+				j->quals = pull_up_sublinks_qual_recurse(root,
+														 j->quals,
+														 &j->larg,
+														 available_rels1,
+														 &j->rarg,
+														 child_rels);
+				/* Return NULL representing constant TRUE */
+				return NULL;
+			}
+			if (available_rels2 != NULL &&
+				(j = convert_EXISTS_sublink_to_join(root, sublink, false,
+													available_rels2)) != NULL)
+			{
+				/* Yes; insert the new join node into the join tree */
+				j->larg = *jtlink2;
+				*jtlink2 = (Node *) j;
+				/* Recursively process pulled-up jointree nodes */
+				j->rarg = pull_up_sublinks_jointree_recurse(root,
+															j->rarg,
+															&child_rels);
+
+				/*
+				 * Now recursively process the pulled-up quals.  Any inserted
+				 * joins can get stacked onto either j->larg or j->rarg,
+				 * depending on which rels they reference.
+				 */
+				j->quals = pull_up_sublinks_qual_recurse(root,
+														 j->quals,
+														 &j->larg,
+														 available_rels2,
+														 &j->rarg,
+														 child_rels);
+				/* Return NULL representing constant TRUE */
+				return NULL;
+			}
+		}
+		/* Else return it unmodified */
+		return node;
+	}
+	if (is_notclause(node))
+	{
+		/* If the immediate argument of NOT is EXISTS, try to convert */
+		SubLink    *sublink = (SubLink *) get_notclausearg((Expr *) node);
+		JoinExpr   *j;
+		Relids		child_rels;
+
+		if (sublink && IsA(sublink, SubLink))
+		{
+			if (sublink->subLinkType == EXISTS_SUBLINK)
+			{
+				if ((j = convert_EXISTS_sublink_to_join(root, sublink, true,
+														available_rels1)) != NULL)
+				{
+					/* Yes; insert the new join node into the join tree */
+					j->larg = *jtlink1;
+					*jtlink1 = (Node *) j;
+					/* Recursively process pulled-up jointree nodes */
+					j->rarg = pull_up_sublinks_jointree_recurse(root,
+																j->rarg,
+																&child_rels);
+
+					/*
+					 * Now recursively process the pulled-up quals.  Because
+					 * we are underneath a NOT, we can't pull up sublinks that
+					 * reference the left-hand stuff, but it's still okay to
+					 * pull up sublinks referencing j->rarg.
+					 */
+					j->quals = pull_up_sublinks_qual_recurse(root,
+															 j->quals,
+															 &j->rarg,
+															 child_rels,
+															 NULL, NULL);
+					/* Return NULL representing constant TRUE */
+					return NULL;
+				}
+				if (available_rels2 != NULL &&
+					(j = convert_EXISTS_sublink_to_join(root, sublink, true,
+														available_rels2)) != NULL)
+				{
+					/* Yes; insert the new join node into the join tree */
+					j->larg = *jtlink2;
+					*jtlink2 = (Node *) j;
+					/* Recursively process pulled-up jointree nodes */
+					j->rarg = pull_up_sublinks_jointree_recurse(root,
+																j->rarg,
+																&child_rels);
+
+					/*
+					 * Now recursively process the pulled-up quals.  Because
+					 * we are underneath a NOT, we can't pull up sublinks that
+					 * reference the left-hand stuff, but it's still okay to
+					 * pull up sublinks referencing j->rarg.
+					 */
+					j->quals = pull_up_sublinks_qual_recurse(root,
+															 j->quals,
+															 &j->rarg,
+															 child_rels,
+															 NULL, NULL);
+					/* Return NULL representing constant TRUE */
+					return NULL;
+				}
+			}
+		}
+		/* Else return it unmodified */
+		return node;
+	}
+	if (is_andclause(node))
+	{
+		/* Recurse into AND clause */
+		List	   *newclauses = NIL;
+		ListCell   *l;
+
+		foreach(l, ((BoolExpr *) node)->args)
+		{
+			Node	   *oldclause = (Node *) lfirst(l);
+			Node	   *newclause;
+
+			newclause = pull_up_sublinks_qual_recurse(root,
+													  oldclause,
+													  jtlink1,
+													  available_rels1,
+													  jtlink2,
+													  available_rels2);
+			if (newclause)
+				newclauses = lappend(newclauses, newclause);
+		}
+		/* We might have got back fewer clauses than we started with */
+		if (newclauses == NIL)
+			return NULL;
+		else if (list_length(newclauses) == 1)
+			return (Node *) linitial(newclauses);
+		else
+			return (Node *) make_andclause(newclauses);
+	}
+	/* Stop if not an AND */
+	return node;
+}
+
+/*
+ * preprocess_function_rtes
+ *		Constant-simplify any FUNCTION RTEs in the FROM clause, and then
+ *		attempt to "inline" any that are set-returning functions.
+ *
+ * If an RTE_FUNCTION rtable entry invokes a set-returning function that
+ * contains just a simple SELECT, we can convert the rtable entry to an
+ * RTE_SUBQUERY entry exposing the SELECT directly.  This is especially
+ * useful if the subquery can then be "pulled up" for further optimization,
+ * but we do it even if not, to reduce executor overhead.
+ *
+ * This has to be done before we have started to do any optimization of
+ * subqueries, else any such steps wouldn't get applied to subqueries
+ * obtained via inlining.  However, we do it after pull_up_sublinks
+ * so that we can inline any functions used in SubLink subselects.
+ *
+ * The reason for applying const-simplification at this stage is that
+ * (a) we'd need to do it anyway to inline a SRF, and (b) by doing it now,
+ * we can be sure that pull_up_constant_function() will see constants
+ * if there are constants to be seen.  This approach also guarantees
+ * that every FUNCTION RTE has been const-simplified, allowing planner.c's
+ * preprocess_expression() to skip doing it again.
+ *
+ * Like most of the planner, this feels free to scribble on its input data
+ * structure.
+ */
+void
+preprocess_function_rtes(PlannerInfo *root)
+{
+	ListCell   *rt;
+
+	foreach(rt, root->parse->rtable)
+	{
+		RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt);
+
+		if (rte->rtekind == RTE_FUNCTION)
+		{
+			Query	   *funcquery;
+
+			/* Apply const-simplification */
+			rte->functions = (List *)
+				eval_const_expressions(root, (Node *) rte->functions);
+
+			/* Check safety of expansion, and expand if possible */
+			funcquery = inline_set_returning_function(root, rte);
+			if (funcquery)
+			{
+				/* Successful expansion, convert the RTE to a subquery */
+				rte->rtekind = RTE_SUBQUERY;
+				rte->subquery = funcquery;
+				rte->security_barrier = false;
+				/* Clear fields that should not be set in a subquery RTE */
+				rte->functions = NIL;
+				rte->funcordinality = false;
+			}
+		}
+	}
+}
+
+/*
+ * pull_up_subqueries
+ *		Look for subqueries in the rangetable that can be pulled up into
+ *		the parent query.  If the subquery has no special features like
+ *		grouping/aggregation then we can merge it into the parent's jointree.
+ *		Also, subqueries that are simple UNION ALL structures can be
+ *		converted into "append relations".
+ */
+void
+pull_up_subqueries(PlannerInfo *root)
+{
+	/* Top level of jointree must always be a FromExpr */
+	Assert(IsA(root->parse->jointree, FromExpr));
+	/* Recursion starts with no containing join nor appendrel */
+	root->parse->jointree = (FromExpr *)
+		pull_up_subqueries_recurse(root, (Node *) root->parse->jointree,
+								   NULL, NULL, NULL);
+	/* We should still have a FromExpr */
+	Assert(IsA(root->parse->jointree, FromExpr));
+}
+
+/*
+ * pull_up_subqueries_recurse
+ *		Recursive guts of pull_up_subqueries.
+ *
+ * This recursively processes the jointree and returns a modified jointree.
+ *
+ * If this jointree node is within either side of an outer join, then
+ * lowest_outer_join references the lowest such JoinExpr node; otherwise
+ * it is NULL.  We use this to constrain the effects of LATERAL subqueries.
+ *
+ * If this jointree node is within the nullable side of an outer join, then
+ * lowest_nulling_outer_join references the lowest such JoinExpr node;
+ * otherwise it is NULL.  This forces use of the PlaceHolderVar mechanism for
+ * references to non-nullable targetlist items, but only for references above
+ * that join.
+ *
+ * If we are looking at a member subquery of an append relation,
+ * containing_appendrel describes that relation; else it is NULL.
+ * This forces use of the PlaceHolderVar mechanism for all non-Var targetlist
+ * items, and puts some additional restrictions on what can be pulled up.
+ *
+ * A tricky aspect of this code is that if we pull up a subquery we have
+ * to replace Vars that reference the subquery's outputs throughout the
+ * parent query, including quals attached to jointree nodes above the one
+ * we are currently processing!  We handle this by being careful to maintain
+ * validity of the jointree structure while recursing, in the following sense:
+ * whenever we recurse, all qual expressions in the tree must be reachable
+ * from the top level, in case the recursive call needs to modify them.
+ *
+ * Notice also that we can't turn pullup_replace_vars loose on the whole
+ * jointree, because it'd return a mutated copy of the tree; we have to
+ * invoke it just on the quals, instead.  This behavior is what makes it
+ * reasonable to pass lowest_outer_join and lowest_nulling_outer_join as
+ * pointers rather than some more-indirect way of identifying the lowest
+ * OJs.  Likewise, we don't replace append_rel_list members but only their
+ * substructure, so the containing_appendrel reference is safe to use.
+ */
+static Node *
+pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
+						   JoinExpr *lowest_outer_join,
+						   JoinExpr *lowest_nulling_outer_join,
+						   AppendRelInfo *containing_appendrel)
+{
+	/* Since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+	/* Also, since it's a bit expensive, let's check for query cancel. */
+	CHECK_FOR_INTERRUPTS();
+
+	Assert(jtnode != NULL);
+	if (IsA(jtnode, RangeTblRef))
+	{
+		int			varno = ((RangeTblRef *) jtnode)->rtindex;
+		RangeTblEntry *rte = rt_fetch(varno, root->parse->rtable);
+
+		/*
+		 * Is this a subquery RTE, and if so, is the subquery simple enough to
+		 * pull up?
+		 *
+		 * If we are looking at an append-relation member, we can't pull it up
+		 * unless is_safe_append_member says so.
+		 */
+		if (rte->rtekind == RTE_SUBQUERY &&
+			is_simple_subquery(root, rte->subquery, rte, lowest_outer_join) &&
+			(containing_appendrel == NULL ||
+			 is_safe_append_member(rte->subquery)))
+			return pull_up_simple_subquery(root, jtnode, rte,
+										   lowest_outer_join,
+										   lowest_nulling_outer_join,
+										   containing_appendrel);
+
+		/*
+		 * Alternatively, is it a simple UNION ALL subquery?  If so, flatten
+		 * into an "append relation".
+		 *
+		 * It's safe to do this regardless of whether this query is itself an
+		 * appendrel member.  (If you're thinking we should try to flatten the
+		 * two levels of appendrel together, you're right; but we handle that
+		 * in set_append_rel_pathlist, not here.)
+		 */
+		if (rte->rtekind == RTE_SUBQUERY &&
+			is_simple_union_all(rte->subquery))
+			return pull_up_simple_union_all(root, jtnode, rte);
+
+		/*
+		 * Or perhaps it's a simple VALUES RTE?
+		 *
+		 * We don't allow VALUES pullup below an outer join nor into an
+		 * appendrel (such cases are impossible anyway at the moment).
+		 */
+		if (rte->rtekind == RTE_VALUES &&
+			lowest_outer_join == NULL &&
+			containing_appendrel == NULL &&
+			is_simple_values(root, rte))
+			return pull_up_simple_values(root, jtnode, rte);
+
+		/*
+		 * Or perhaps it's a FUNCTION RTE that we could inline?
+		 */
+		if (rte->rtekind == RTE_FUNCTION)
+			return pull_up_constant_function(root, jtnode, rte,
+											 lowest_nulling_outer_join,
+											 containing_appendrel);
+
+		/* Otherwise, do nothing at this node. */
+	}
+	else if (IsA(jtnode, FromExpr))
+	{
+		FromExpr   *f = (FromExpr *) jtnode;
+		ListCell   *l;
+
+		Assert(containing_appendrel == NULL);
+		/* Recursively transform all the child nodes */
+		foreach(l, f->fromlist)
+		{
+			lfirst(l) = pull_up_subqueries_recurse(root, lfirst(l),
+												   lowest_outer_join,
+												   lowest_nulling_outer_join,
+												   NULL);
+		}
+	}
+	else if (IsA(jtnode, JoinExpr))
+	{
+		JoinExpr   *j = (JoinExpr *) jtnode;
+
+		Assert(containing_appendrel == NULL);
+		/* Recurse, being careful to tell myself when inside outer join */
+		switch (j->jointype)
+		{
+			case JOIN_INNER:
+				j->larg = pull_up_subqueries_recurse(root, j->larg,
+													 lowest_outer_join,
+													 lowest_nulling_outer_join,
+													 NULL);
+				j->rarg = pull_up_subqueries_recurse(root, j->rarg,
+													 lowest_outer_join,
+													 lowest_nulling_outer_join,
+													 NULL);
+				break;
+			case JOIN_LEFT:
+			case JOIN_SEMI:
+			case JOIN_ANTI:
+				j->larg = pull_up_subqueries_recurse(root, j->larg,
+													 j,
+													 lowest_nulling_outer_join,
+													 NULL);
+				j->rarg = pull_up_subqueries_recurse(root, j->rarg,
+													 j,
+													 j,
+													 NULL);
+				break;
+			case JOIN_FULL:
+				j->larg = pull_up_subqueries_recurse(root, j->larg,
+													 j,
+													 j,
+													 NULL);
+				j->rarg = pull_up_subqueries_recurse(root, j->rarg,
+													 j,
+													 j,
+													 NULL);
+				break;
+			case JOIN_RIGHT:
+				j->larg = pull_up_subqueries_recurse(root, j->larg,
+													 j,
+													 j,
+													 NULL);
+				j->rarg = pull_up_subqueries_recurse(root, j->rarg,
+													 j,
+													 lowest_nulling_outer_join,
+													 NULL);
+				break;
+			default:
+				elog(ERROR, "unrecognized join type: %d",
+					 (int) j->jointype);
+				break;
+		}
+	}
+	else
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(jtnode));
+	return jtnode;
+}
+
+/*
+ * pull_up_simple_subquery
+ *		Attempt to pull up a single simple subquery.
+ *
+ * jtnode is a RangeTblRef that has been tentatively identified as a simple
+ * subquery by pull_up_subqueries.  We return the replacement jointree node,
+ * or jtnode itself if we determine that the subquery can't be pulled up
+ * after all.
+ *
+ * rte is the RangeTblEntry referenced by jtnode.  Remaining parameters are
+ * as for pull_up_subqueries_recurse.
+ */
+static Node *
+pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
+						JoinExpr *lowest_outer_join,
+						JoinExpr *lowest_nulling_outer_join,
+						AppendRelInfo *containing_appendrel)
+{
+	Query	   *parse = root->parse;
+	int			varno = ((RangeTblRef *) jtnode)->rtindex;
+	Query	   *subquery;
+	PlannerInfo *subroot;
+	int			rtoffset;
+	pullup_replace_vars_context rvcontext;
+	ListCell   *lc;
+
+	/*
+	 * Make a modifiable copy of the subquery to hack on, so that the RTE will
+	 * be left unchanged in case we decide below that we can't pull it up
+	 * after all.
+	 */
+	subquery = copyObject(rte->subquery);
+
+	/*
+	 * Create a PlannerInfo data structure for this subquery.
+	 *
+	 * NOTE: the next few steps should match the first processing in
+	 * subquery_planner().  Can we refactor to avoid code duplication, or
+	 * would that just make things uglier?
+	 */
+	subroot = makeNode(PlannerInfo);
+	subroot->parse = subquery;
+	subroot->glob = root->glob;
+	subroot->query_level = root->query_level;
+	subroot->parent_root = root->parent_root;
+	subroot->plan_params = NIL;
+	subroot->outer_params = NULL;
+	subroot->planner_cxt = CurrentMemoryContext;
+	subroot->init_plans = NIL;
+	subroot->cte_plan_ids = NIL;
+	subroot->multiexpr_params = NIL;
+	subroot->eq_classes = NIL;
+	subroot->ec_merging_done = false;
+	subroot->all_result_relids = NULL;
+	subroot->leaf_result_relids = NULL;
+	subroot->append_rel_list = NIL;
+	subroot->row_identity_vars = NIL;
+	subroot->rowMarks = NIL;
+	memset(subroot->upper_rels, 0, sizeof(subroot->upper_rels));
+	memset(subroot->upper_targets, 0, sizeof(subroot->upper_targets));
+	subroot->processed_tlist = NIL;
+	subroot->update_colnos = NIL;
+	subroot->grouping_map = NULL;
+	subroot->minmax_aggs = NIL;
+	subroot->qual_security_level = 0;
+	subroot->hasRecursion = false;
+	subroot->wt_param_id = -1;
+	subroot->non_recursive_path = NULL;
+
+	/* No CTEs to worry about */
+	Assert(subquery->cteList == NIL);
+
+	/*
+	 * If the FROM clause is empty, replace it with a dummy RTE_RESULT RTE, so
+	 * that we don't need so many special cases to deal with that situation.
+	 */
+	replace_empty_jointree(subquery);
+
+	/*
+	 * Pull up any SubLinks within the subquery's quals, so that we don't
+	 * leave unoptimized SubLinks behind.
+	 */
+	if (subquery->hasSubLinks)
+		pull_up_sublinks(subroot);
+
+	/*
+	 * Similarly, preprocess its function RTEs to inline any set-returning
+	 * functions in its rangetable.
+	 */
+	preprocess_function_rtes(subroot);
+
+	/*
+	 * Recursively pull up the subquery's subqueries, so that
+	 * pull_up_subqueries' processing is complete for its jointree and
+	 * rangetable.
+	 *
+	 * Note: it's okay that the subquery's recursion starts with NULL for
+	 * containing-join info, even if we are within an outer join in the upper
+	 * query; the lower query starts with a clean slate for outer-join
+	 * semantics.  Likewise, we needn't pass down appendrel state.
+	 */
+	pull_up_subqueries(subroot);
+
+	/*
+	 * Now we must recheck whether the subquery is still simple enough to pull
+	 * up.  If not, abandon processing it.
+	 *
+	 * We don't really need to recheck all the conditions involved, but it's
+	 * easier just to keep this "if" looking the same as the one in
+	 * pull_up_subqueries_recurse.
+	 */
+	if (is_simple_subquery(root, subquery, rte, lowest_outer_join) &&
+		(containing_appendrel == NULL || is_safe_append_member(subquery)))
+	{
+		/* good to go */
+	}
+	else
+	{
+		/*
+		 * Give up, return unmodified RangeTblRef.
+		 *
+		 * Note: The work we just did will be redone when the subquery gets
+		 * planned on its own.  Perhaps we could avoid that by storing the
+		 * modified subquery back into the rangetable, but I'm not gonna risk
+		 * it now.
+		 */
+		return jtnode;
+	}
+
+	/*
+	 * We must flatten any join alias Vars in the subquery's targetlist,
+	 * because pulling up the subquery's subqueries might have changed their
+	 * expansions into arbitrary expressions, which could affect
+	 * pullup_replace_vars' decisions about whether PlaceHolderVar wrappers
+	 * are needed for tlist entries.  (Likely it'd be better to do
+	 * flatten_join_alias_vars on the whole query tree at some earlier stage,
+	 * maybe even in the rewriter; but for now let's just fix this case here.)
+	 */
+	subquery->targetList = (List *)
+		flatten_join_alias_vars(subroot->parse, (Node *) subquery->targetList);
+
+	/*
+	 * Adjust level-0 varnos in subquery so that we can append its rangetable
+	 * to upper query's.  We have to fix the subquery's append_rel_list as
+	 * well.
+	 */
+	rtoffset = list_length(parse->rtable);
+	OffsetVarNodes((Node *) subquery, rtoffset, 0);
+	OffsetVarNodes((Node *) subroot->append_rel_list, rtoffset, 0);
+
+	/*
+	 * Upper-level vars in subquery are now one level closer to their parent
+	 * than before.
+	 */
+	IncrementVarSublevelsUp((Node *) subquery, -1, 1);
+	IncrementVarSublevelsUp((Node *) subroot->append_rel_list, -1, 1);
+
+	/*
+	 * The subquery's targetlist items are now in the appropriate form to
+	 * insert into the top query, except that we may need to wrap them in
+	 * PlaceHolderVars.  Set up required context data for pullup_replace_vars.
+	 */
+	rvcontext.root = root;
+	rvcontext.targetlist = subquery->targetList;
+	rvcontext.target_rte = rte;
+	if (rte->lateral)
+		rvcontext.relids = get_relids_in_jointree((Node *) subquery->jointree,
+												  true);
+	else						/* won't need relids */
+		rvcontext.relids = NULL;
+	rvcontext.outer_hasSubLinks = &parse->hasSubLinks;
+	rvcontext.varno = varno;
+	/* these flags will be set below, if needed */
+	rvcontext.need_phvs = false;
+	rvcontext.wrap_non_vars = false;
+	/* initialize cache array with indexes 0 .. length(tlist) */
+	rvcontext.rv_cache = palloc0((list_length(subquery->targetList) + 1) *
+								 sizeof(Node *));
+
+	/*
+	 * If we are under an outer join then non-nullable items and lateral
+	 * references may have to be turned into PlaceHolderVars.
+	 */
+	if (lowest_nulling_outer_join != NULL)
+		rvcontext.need_phvs = true;
+
+	/*
+	 * If we are dealing with an appendrel member then anything that's not a
+	 * simple Var has to be turned into a PlaceHolderVar.  We force this to
+	 * ensure that what we pull up doesn't get merged into a surrounding
+	 * expression during later processing and then fail to match the
+	 * expression actually available from the appendrel.
+	 */
+	if (containing_appendrel != NULL)
+	{
+		rvcontext.need_phvs = true;
+		rvcontext.wrap_non_vars = true;
+	}
+
+	/*
+	 * If the parent query uses grouping sets, we need a PlaceHolderVar for
+	 * anything that's not a simple Var.  Again, this ensures that expressions
+	 * retain their separate identity so that they will match grouping set
+	 * columns when appropriate.  (It'd be sufficient to wrap values used in
+	 * grouping set columns, and do so only in non-aggregated portions of the
+	 * tlist and havingQual, but that would require a lot of infrastructure
+	 * that pullup_replace_vars hasn't currently got.)
+	 */
+	if (parse->groupingSets)
+	{
+		rvcontext.need_phvs = true;
+		rvcontext.wrap_non_vars = true;
+	}
+
+	/*
+	 * Replace all of the top query's references to the subquery's outputs
+	 * with copies of the adjusted subtlist items, being careful not to
+	 * replace any of the jointree structure.
+	 */
+	perform_pullup_replace_vars(root, &rvcontext,
+								lowest_nulling_outer_join,
+								containing_appendrel);
+
+	/*
+	 * If the subquery had a LATERAL marker, propagate that to any of its
+	 * child RTEs that could possibly now contain lateral cross-references.
+	 * The children might or might not contain any actual lateral
+	 * cross-references, but we have to mark the pulled-up child RTEs so that
+	 * later planner stages will check for such.
+	 */
+	if (rte->lateral)
+	{
+		foreach(lc, subquery->rtable)
+		{
+			RangeTblEntry *child_rte = (RangeTblEntry *) lfirst(lc);
+
+			switch (child_rte->rtekind)
+			{
+				case RTE_RELATION:
+					if (child_rte->tablesample)
+						child_rte->lateral = true;
+					break;
+				case RTE_SUBQUERY:
+				case RTE_FUNCTION:
+				case RTE_VALUES:
+				case RTE_TABLEFUNC:
+					child_rte->lateral = true;
+					break;
+				case RTE_JOIN:
+				case RTE_CTE:
+				case RTE_NAMEDTUPLESTORE:
+				case RTE_RESULT:
+					/* these can't contain any lateral references */
+					break;
+			}
+		}
+	}
+
+	/*
+	 * Now append the adjusted rtable entries to upper query. (We hold off
+	 * until after fixing the upper rtable entries; no point in running that
+	 * code on the subquery ones too.)
+	 */
+	parse->rtable = list_concat(parse->rtable, subquery->rtable);
+
+	/*
+	 * Pull up any FOR UPDATE/SHARE markers, too.  (OffsetVarNodes already
+	 * adjusted the marker rtindexes, so just concat the lists.)
+	 */
+	parse->rowMarks = list_concat(parse->rowMarks, subquery->rowMarks);
+
+	/*
+	 * We also have to fix the relid sets of any PlaceHolderVar nodes in the
+	 * parent query.  (This could perhaps be done by pullup_replace_vars(),
+	 * but it seems cleaner to use two passes.)  Note in particular that any
+	 * PlaceHolderVar nodes just created by pullup_replace_vars() will be
+	 * adjusted, so having created them with the subquery's varno is correct.
+	 *
+	 * Likewise, relids appearing in AppendRelInfo nodes have to be fixed. We
+	 * already checked that this won't require introducing multiple subrelids
+	 * into the single-slot AppendRelInfo structs.
+	 */
+	if (parse->hasSubLinks || root->glob->lastPHId != 0 ||
+		root->append_rel_list)
+	{
+		Relids		subrelids;
+
+		subrelids = get_relids_in_jointree((Node *) subquery->jointree, false);
+		substitute_phv_relids((Node *) parse, varno, subrelids);
+		fix_append_rel_relids(root->append_rel_list, varno, subrelids);
+	}
+
+	/*
+	 * And now add subquery's AppendRelInfos to our list.
+	 */
+	root->append_rel_list = list_concat(root->append_rel_list,
+										subroot->append_rel_list);
+
+	/*
+	 * We don't have to do the equivalent bookkeeping for outer-join info,
+	 * because that hasn't been set up yet.  placeholder_list likewise.
+	 */
+	Assert(root->join_info_list == NIL);
+	Assert(subroot->join_info_list == NIL);
+	Assert(root->placeholder_list == NIL);
+	Assert(subroot->placeholder_list == NIL);
+
+	/*
+	 * We no longer need the RTE's copy of the subquery's query tree.  Getting
+	 * rid of it saves nothing in particular so far as this level of query is
+	 * concerned; but if this query level is in turn pulled up into a parent,
+	 * we'd waste cycles copying the now-unused query tree.
+	 */
+	rte->subquery = NULL;
+
+	/*
+	 * Miscellaneous housekeeping.
+	 *
+	 * Although replace_rte_variables() faithfully updated parse->hasSubLinks
+	 * if it copied any SubLinks out of the subquery's targetlist, we still
+	 * could have SubLinks added to the query in the expressions of FUNCTION
+	 * and VALUES RTEs copied up from the subquery.  So it's necessary to copy
+	 * subquery->hasSubLinks anyway.  Perhaps this can be improved someday.
+	 */
+	parse->hasSubLinks |= subquery->hasSubLinks;
+
+	/* If subquery had any RLS conditions, now main query does too */
+	parse->hasRowSecurity |= subquery->hasRowSecurity;
+
+	/*
+	 * subquery won't be pulled up if it hasAggs, hasWindowFuncs, or
+	 * hasTargetSRFs, so no work needed on those flags
+	 */
+
+	/*
+	 * Return the adjusted subquery jointree to replace the RangeTblRef entry
+	 * in parent's jointree; or, if the FromExpr is degenerate, just return
+	 * its single member.
+	 */
+	Assert(IsA(subquery->jointree, FromExpr));
+	Assert(subquery->jointree->fromlist != NIL);
+	if (subquery->jointree->quals == NULL &&
+		list_length(subquery->jointree->fromlist) == 1)
+		return (Node *) linitial(subquery->jointree->fromlist);
+
+	return (Node *) subquery->jointree;
+}
+
+/*
+ * pull_up_simple_union_all
+ *		Pull up a single simple UNION ALL subquery.
+ *
+ * jtnode is a RangeTblRef that has been identified as a simple UNION ALL
+ * subquery by pull_up_subqueries.  We pull up the leaf subqueries and
+ * build an "append relation" for the union set.  The result value is just
+ * jtnode, since we don't actually need to change the query jointree.
+ */
+static Node *
+pull_up_simple_union_all(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte)
+{
+	int			varno = ((RangeTblRef *) jtnode)->rtindex;
+	Query	   *subquery = rte->subquery;
+	int			rtoffset = list_length(root->parse->rtable);
+	List	   *rtable;
+
+	/*
+	 * Make a modifiable copy of the subquery's rtable, so we can adjust
+	 * upper-level Vars in it.  There are no such Vars in the setOperations
+	 * tree proper, so fixing the rtable should be sufficient.
+	 */
+	rtable = copyObject(subquery->rtable);
+
+	/*
+	 * Upper-level vars in subquery are now one level closer to their parent
+	 * than before.  We don't have to worry about offsetting varnos, though,
+	 * because the UNION leaf queries can't cross-reference each other.
+	 */
+	IncrementVarSublevelsUp_rtable(rtable, -1, 1);
+
+	/*
+	 * If the UNION ALL subquery had a LATERAL marker, propagate that to all
+	 * its children.  The individual children might or might not contain any
+	 * actual lateral cross-references, but we have to mark the pulled-up
+	 * child RTEs so that later planner stages will check for such.
+	 */
+	if (rte->lateral)
+	{
+		ListCell   *rt;
+
+		foreach(rt, rtable)
+		{
+			RangeTblEntry *child_rte = (RangeTblEntry *) lfirst(rt);
+
+			Assert(child_rte->rtekind == RTE_SUBQUERY);
+			child_rte->lateral = true;
+		}
+	}
+
+	/*
+	 * Append child RTEs to parent rtable.
+	 */
+	root->parse->rtable = list_concat(root->parse->rtable, rtable);
+
+	/*
+	 * Recursively scan the subquery's setOperations tree and add
+	 * AppendRelInfo nodes for leaf subqueries to the parent's
+	 * append_rel_list.  Also apply pull_up_subqueries to the leaf subqueries.
+	 */
+	Assert(subquery->setOperations);
+	pull_up_union_leaf_queries(subquery->setOperations, root, varno, subquery,
+							   rtoffset);
+
+	/*
+	 * Mark the parent as an append relation.
+	 */
+	rte->inh = true;
+
+	return jtnode;
+}
+
+/*
+ * pull_up_union_leaf_queries -- recursive guts of pull_up_simple_union_all
+ *
+ * Build an AppendRelInfo for each leaf query in the setop tree, and then
+ * apply pull_up_subqueries to the leaf query.
+ *
+ * Note that setOpQuery is the Query containing the setOp node, whose tlist
+ * contains references to all the setop output columns.  When called from
+ * pull_up_simple_union_all, this is *not* the same as root->parse, which is
+ * the parent Query we are pulling up into.
+ *
+ * parentRTindex is the appendrel parent's index in root->parse->rtable.
+ *
+ * The child RTEs have already been copied to the parent.  childRToffset
+ * tells us where in the parent's range table they were copied.  When called
+ * from flatten_simple_union_all, childRToffset is 0 since the child RTEs
+ * were already in root->parse->rtable and no RT index adjustment is needed.
+ */
+static void
+pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root, int parentRTindex,
+						   Query *setOpQuery, int childRToffset)
+{
+	if (IsA(setOp, RangeTblRef))
+	{
+		RangeTblRef *rtr = (RangeTblRef *) setOp;
+		int			childRTindex;
+		AppendRelInfo *appinfo;
+
+		/*
+		 * Calculate the index in the parent's range table
+		 */
+		childRTindex = childRToffset + rtr->rtindex;
+
+		/*
+		 * Build a suitable AppendRelInfo, and attach to parent's list.
+		 */
+		appinfo = makeNode(AppendRelInfo);
+		appinfo->parent_relid = parentRTindex;
+		appinfo->child_relid = childRTindex;
+		appinfo->parent_reltype = InvalidOid;
+		appinfo->child_reltype = InvalidOid;
+		make_setop_translation_list(setOpQuery, childRTindex, appinfo);
+		appinfo->parent_reloid = InvalidOid;
+		root->append_rel_list = lappend(root->append_rel_list, appinfo);
+
+		/*
+		 * Recursively apply pull_up_subqueries to the new child RTE.  (We
+		 * must build the AppendRelInfo first, because this will modify it.)
+		 * Note that we can pass NULL for containing-join info even if we're
+		 * actually under an outer join, because the child's expressions
+		 * aren't going to propagate up to the join.  Also, we ignore the
+		 * possibility that pull_up_subqueries_recurse() returns a different
+		 * jointree node than what we pass it; if it does, the important thing
+		 * is that it replaced the child relid in the AppendRelInfo node.
+		 */
+		rtr = makeNode(RangeTblRef);
+		rtr->rtindex = childRTindex;
+		(void) pull_up_subqueries_recurse(root, (Node *) rtr,
+										  NULL, NULL, appinfo);
+	}
+	else if (IsA(setOp, SetOperationStmt))
+	{
+		SetOperationStmt *op = (SetOperationStmt *) setOp;
+
+		/* Recurse to reach leaf queries */
+		pull_up_union_leaf_queries(op->larg, root, parentRTindex, setOpQuery,
+								   childRToffset);
+		pull_up_union_leaf_queries(op->rarg, root, parentRTindex, setOpQuery,
+								   childRToffset);
+	}
+	else
+	{
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(setOp));
+	}
+}
+
+/*
+ * make_setop_translation_list
+ *	  Build the list of translations from parent Vars to child Vars for
+ *	  a UNION ALL member.  (At this point it's just a simple list of
+ *	  referencing Vars, but if we succeed in pulling up the member
+ *	  subquery, the Vars will get replaced by pulled-up expressions.)
+ *	  Also create the rather trivial reverse-translation array.
+ */
+static void
+make_setop_translation_list(Query *query, int newvarno,
+							AppendRelInfo *appinfo)
+{
+	List	   *vars = NIL;
+	AttrNumber *pcolnos;
+	ListCell   *l;
+
+	/* Initialize reverse-translation array with all entries zero */
+	/* (entries for resjunk columns will stay that way) */
+	appinfo->num_child_cols = list_length(query->targetList);
+	appinfo->parent_colnos = pcolnos =
+		(AttrNumber *) palloc0(appinfo->num_child_cols * sizeof(AttrNumber));
+
+	foreach(l, query->targetList)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
+
+		if (tle->resjunk)
+			continue;
+
+		vars = lappend(vars, makeVarFromTargetEntry(newvarno, tle));
+		pcolnos[tle->resno - 1] = tle->resno;
+	}
+
+	appinfo->translated_vars = vars;
+}
+
+/*
+ * is_simple_subquery
+ *	  Check a subquery in the range table to see if it's simple enough
+ *	  to pull up into the parent query.
+ *
+ * rte is the RTE_SUBQUERY RangeTblEntry that contained the subquery.
+ * (Note subquery is not necessarily equal to rte->subquery; it could be a
+ * processed copy of that.)
+ * lowest_outer_join is the lowest outer join above the subquery, or NULL.
+ */
+static bool
+is_simple_subquery(PlannerInfo *root, Query *subquery, RangeTblEntry *rte,
+				   JoinExpr *lowest_outer_join)
+{
+	/*
+	 * Let's just make sure it's a valid subselect ...
+	 */
+	if (!IsA(subquery, Query) ||
+		subquery->commandType != CMD_SELECT)
+		elog(ERROR, "subquery is bogus");
+
+	/*
+	 * Can't currently pull up a query with setops (unless it's simple UNION
+	 * ALL, which is handled by a different code path). Maybe after querytree
+	 * redesign...
+	 */
+	if (subquery->setOperations)
+		return false;
+
+	/*
+	 * Can't pull up a subquery involving grouping, aggregation, SRFs,
+	 * sorting, limiting, or WITH.  (XXX WITH could possibly be allowed later)
+	 *
+	 * We also don't pull up a subquery that has explicit FOR UPDATE/SHARE
+	 * clauses, because pullup would cause the locking to occur semantically
+	 * higher than it should.  Implicit FOR UPDATE/SHARE is okay because in
+	 * that case the locking was originally declared in the upper query
+	 * anyway.
+	 */
+	if (subquery->hasAggs ||
+		subquery->hasWindowFuncs ||
+		subquery->hasTargetSRFs ||
+		subquery->groupClause ||
+		subquery->groupingSets ||
+		subquery->havingQual ||
+		subquery->sortClause ||
+		subquery->distinctClause ||
+		subquery->limitOffset ||
+		subquery->limitCount ||
+		subquery->hasForUpdate ||
+		subquery->cteList)
+		return false;
+
+	/*
+	 * Don't pull up if the RTE represents a security-barrier view; we
+	 * couldn't prevent information leakage once the RTE's Vars are scattered
+	 * about in the upper query.
+	 */
+	if (rte->security_barrier)
+		return false;
+
+	/*
+	 * If the subquery is LATERAL, check for pullup restrictions from that.
+	 */
+	if (rte->lateral)
+	{
+		bool		restricted;
+		Relids		safe_upper_varnos;
+
+		/*
+		 * The subquery's WHERE and JOIN/ON quals mustn't contain any lateral
+		 * references to rels outside a higher outer join (including the case
+		 * where the outer join is within the subquery itself).  In such a
+		 * case, pulling up would result in a situation where we need to
+		 * postpone quals from below an outer join to above it, which is
+		 * probably completely wrong and in any case is a complication that
+		 * doesn't seem worth addressing at the moment.
+		 */
+		if (lowest_outer_join != NULL)
+		{
+			restricted = true;
+			safe_upper_varnos = get_relids_in_jointree((Node *) lowest_outer_join,
+													   true);
+		}
+		else
+		{
+			restricted = false;
+			safe_upper_varnos = NULL;	/* doesn't matter */
+		}
+
+		if (jointree_contains_lateral_outer_refs(root,
+												 (Node *) subquery->jointree,
+												 restricted, safe_upper_varnos))
+			return false;
+
+		/*
+		 * If there's an outer join above the LATERAL subquery, also disallow
+		 * pullup if the subquery's targetlist has any references to rels
+		 * outside the outer join, since these might get pulled into quals
+		 * above the subquery (but in or below the outer join) and then lead
+		 * to qual-postponement issues similar to the case checked for above.
+		 * (We wouldn't need to prevent pullup if no such references appear in
+		 * outer-query quals, but we don't have enough info here to check
+		 * that.  Also, maybe this restriction could be removed if we forced
+		 * such refs to be wrapped in PlaceHolderVars, even when they're below
+		 * the nearest outer join?	But it's a pretty hokey usage, so not
+		 * clear this is worth sweating over.)
+		 */
+		if (lowest_outer_join != NULL)
+		{
+			Relids		lvarnos = pull_varnos_of_level(root,
+													   (Node *) subquery->targetList,
+													   1);
+
+			if (!bms_is_subset(lvarnos, safe_upper_varnos))
+				return false;
+		}
+	}
+
+	/*
+	 * Don't pull up a subquery that has any volatile functions in its
+	 * targetlist.  Otherwise we might introduce multiple evaluations of these
+	 * functions, if they get copied to multiple places in the upper query,
+	 * leading to surprising results.  (Note: the PlaceHolderVar mechanism
+	 * doesn't quite guarantee single evaluation; else we could pull up anyway
+	 * and just wrap such items in PlaceHolderVars ...)
+	 */
+	if (contain_volatile_functions((Node *) subquery->targetList))
+		return false;
+
+	return true;
+}
+
+/*
+ * pull_up_simple_values
+ *		Pull up a single simple VALUES RTE.
+ *
+ * jtnode is a RangeTblRef that has been identified as a simple VALUES RTE
+ * by pull_up_subqueries.  We always return a RangeTblRef representing a
+ * RESULT RTE to replace it (all failure cases should have been detected by
+ * is_simple_values()).  Actually, what we return is just jtnode, because
+ * we replace the VALUES RTE in the rangetable with the RESULT RTE.
+ *
+ * rte is the RangeTblEntry referenced by jtnode.  Because of the limited
+ * possible usage of VALUES RTEs, we do not need the remaining parameters
+ * of pull_up_subqueries_recurse.
+ */
+static Node *
+pull_up_simple_values(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte)
+{
+	Query	   *parse = root->parse;
+	int			varno = ((RangeTblRef *) jtnode)->rtindex;
+	List	   *values_list;
+	List	   *tlist;
+	AttrNumber	attrno;
+	pullup_replace_vars_context rvcontext;
+	ListCell   *lc;
+
+	Assert(rte->rtekind == RTE_VALUES);
+	Assert(list_length(rte->values_lists) == 1);
+
+	/*
+	 * Need a modifiable copy of the VALUES list to hack on, just in case it's
+	 * multiply referenced.
+	 */
+	values_list = copyObject(linitial(rte->values_lists));
+
+	/*
+	 * The VALUES RTE can't contain any Vars of level zero, let alone any that
+	 * are join aliases, so no need to flatten join alias Vars.
+	 */
+	Assert(!contain_vars_of_level((Node *) values_list, 0));
+
+	/*
+	 * Set up required context data for pullup_replace_vars.  In particular,
+	 * we have to make the VALUES list look like a subquery targetlist.
+	 */
+	tlist = NIL;
+	attrno = 1;
+	foreach(lc, values_list)
+	{
+		tlist = lappend(tlist,
+						makeTargetEntry((Expr *) lfirst(lc),
+										attrno,
+										NULL,
+										false));
+		attrno++;
+	}
+	rvcontext.root = root;
+	rvcontext.targetlist = tlist;
+	rvcontext.target_rte = rte;
+	rvcontext.relids = NULL;
+	rvcontext.outer_hasSubLinks = &parse->hasSubLinks;
+	rvcontext.varno = varno;
+	rvcontext.need_phvs = false;
+	rvcontext.wrap_non_vars = false;
+	/* initialize cache array with indexes 0 .. length(tlist) */
+	rvcontext.rv_cache = palloc0((list_length(tlist) + 1) *
+								 sizeof(Node *));
+
+	/*
+	 * Replace all of the top query's references to the RTE's outputs with
+	 * copies of the adjusted VALUES expressions, being careful not to replace
+	 * any of the jointree structure.  We can assume there's no outer joins or
+	 * appendrels in the dummy Query that surrounds a VALUES RTE.
+	 */
+	perform_pullup_replace_vars(root, &rvcontext, NULL, NULL);
+
+	/*
+	 * There should be no appendrels to fix, nor any outer joins and hence no
+	 * PlaceHolderVars.
+	 */
+	Assert(root->append_rel_list == NIL);
+	Assert(root->join_info_list == NIL);
+	Assert(root->placeholder_list == NIL);
+
+	/*
+	 * Replace the VALUES RTE with a RESULT RTE.  The VALUES RTE is the only
+	 * rtable entry in the current query level, so this is easy.
+	 */
+	Assert(list_length(parse->rtable) == 1);
+
+	/* Create suitable RTE */
+	rte = makeNode(RangeTblEntry);
+	rte->rtekind = RTE_RESULT;
+	rte->eref = makeAlias("*RESULT*", NIL);
+
+	/* Replace rangetable */
+	parse->rtable = list_make1(rte);
+
+	/* We could manufacture a new RangeTblRef, but the one we have is fine */
+	Assert(varno == 1);
+
+	return jtnode;
+}
+
+/*
+ * is_simple_values
+ *	  Check a VALUES RTE in the range table to see if it's simple enough
+ *	  to pull up into the parent query.
+ *
+ * rte is the RTE_VALUES RangeTblEntry to check.
+ */
+static bool
+is_simple_values(PlannerInfo *root, RangeTblEntry *rte)
+{
+	Assert(rte->rtekind == RTE_VALUES);
+
+	/*
+	 * There must be exactly one VALUES list, else it's not semantically
+	 * correct to replace the VALUES RTE with a RESULT RTE, nor would we have
+	 * a unique set of expressions to substitute into the parent query.
+	 */
+	if (list_length(rte->values_lists) != 1)
+		return false;
+
+	/*
+	 * Because VALUES can't appear under an outer join (or at least, we won't
+	 * try to pull it up if it does), we need not worry about LATERAL, nor
+	 * about validity of PHVs for the VALUES' outputs.
+	 */
+
+	/*
+	 * Don't pull up a VALUES that contains any set-returning or volatile
+	 * functions.  The considerations here are basically identical to the
+	 * restrictions on a pull-able subquery's targetlist.
+	 */
+	if (expression_returns_set((Node *) rte->values_lists) ||
+		contain_volatile_functions((Node *) rte->values_lists))
+		return false;
+
+	/*
+	 * Do not pull up a VALUES that's not the only RTE in its parent query.
+	 * This is actually the only case that the parser will generate at the
+	 * moment, and assuming this is true greatly simplifies
+	 * pull_up_simple_values().
+	 */
+	if (list_length(root->parse->rtable) != 1 ||
+		rte != (RangeTblEntry *) linitial(root->parse->rtable))
+		return false;
+
+	return true;
+}
+
+/*
+ * pull_up_constant_function
+ *		Pull up an RTE_FUNCTION expression that was simplified to a constant.
+ *
+ * jtnode is a RangeTblRef that has been identified as a FUNCTION RTE by
+ * pull_up_subqueries.  If its expression is just a Const, hoist that value
+ * up into the parent query, and replace the RTE_FUNCTION with RTE_RESULT.
+ *
+ * In principle we could pull up any immutable expression, but we don't.
+ * That might result in multiple evaluations of the expression, which could
+ * be costly if it's not just a Const.  Also, the main value of this is
+ * to let the constant participate in further const-folding, and of course
+ * that won't happen for a non-Const.
+ *
+ * The pulled-up value might need to be wrapped in a PlaceHolderVar if the
+ * RTE is below an outer join or is part of an appendrel; the extra
+ * parameters show whether that's needed.
+ */
+static Node *
+pull_up_constant_function(PlannerInfo *root, Node *jtnode,
+						  RangeTblEntry *rte,
+						  JoinExpr *lowest_nulling_outer_join,
+						  AppendRelInfo *containing_appendrel)
+{
+	Query	   *parse = root->parse;
+	RangeTblFunction *rtf;
+	TypeFuncClass functypclass;
+	Oid			funcrettype;
+	TupleDesc	tupdesc;
+	pullup_replace_vars_context rvcontext;
+
+	/* Fail if the RTE has ORDINALITY - we don't implement that here. */
+	if (rte->funcordinality)
+		return jtnode;
+
+	/* Fail if RTE isn't a single, simple Const expr */
+	if (list_length(rte->functions) != 1)
+		return jtnode;
+	rtf = linitial_node(RangeTblFunction, rte->functions);
+	if (!IsA(rtf->funcexpr, Const))
+		return jtnode;
+
+	/*
+	 * If the function's result is not a scalar, we punt.  In principle we
+	 * could break the composite constant value apart into per-column
+	 * constants, but for now it seems not worth the work.
+	 */
+	if (rtf->funccolcount != 1)
+		return jtnode;			/* definitely composite */
+
+	functypclass = get_expr_result_type(rtf->funcexpr,
+										&funcrettype,
+										&tupdesc);
+	if (functypclass != TYPEFUNC_SCALAR)
+		return jtnode;			/* must be a one-column composite type */
+
+	/* Create context for applying pullup_replace_vars */
+	rvcontext.root = root;
+	rvcontext.targetlist = list_make1(makeTargetEntry((Expr *) rtf->funcexpr,
+													  1,	/* resno */
+													  NULL, /* resname */
+													  false));	/* resjunk */
+	rvcontext.target_rte = rte;
+
+	/*
+	 * Since this function was reduced to a Const, it doesn't contain any
+	 * lateral references, even if it's marked as LATERAL.  This means we
+	 * don't need to fill relids.
+	 */
+	rvcontext.relids = NULL;
+
+	rvcontext.outer_hasSubLinks = &parse->hasSubLinks;
+	rvcontext.varno = ((RangeTblRef *) jtnode)->rtindex;
+	/* these flags will be set below, if needed */
+	rvcontext.need_phvs = false;
+	rvcontext.wrap_non_vars = false;
+	/* initialize cache array with indexes 0 .. length(tlist) */
+	rvcontext.rv_cache = palloc0((list_length(rvcontext.targetlist) + 1) *
+								 sizeof(Node *));
+
+	/*
+	 * If we are under an outer join then non-nullable items and lateral
+	 * references may have to be turned into PlaceHolderVars.
+	 */
+	if (lowest_nulling_outer_join != NULL)
+		rvcontext.need_phvs = true;
+
+	/*
+	 * If we are dealing with an appendrel member then anything that's not a
+	 * simple Var has to be turned into a PlaceHolderVar.  (See comments in
+	 * pull_up_simple_subquery().)
+	 */
+	if (containing_appendrel != NULL)
+	{
+		rvcontext.need_phvs = true;
+		rvcontext.wrap_non_vars = true;
+	}
+
+	/*
+	 * If the parent query uses grouping sets, we need a PlaceHolderVar for
+	 * anything that's not a simple Var.
+	 */
+	if (parse->groupingSets)
+	{
+		rvcontext.need_phvs = true;
+		rvcontext.wrap_non_vars = true;
+	}
+
+	/*
+	 * Replace all of the top query's references to the RTE's output with
+	 * copies of the funcexpr, being careful not to replace any of the
+	 * jointree structure.
+	 */
+	perform_pullup_replace_vars(root, &rvcontext,
+								lowest_nulling_outer_join,
+								containing_appendrel);
+
+	/*
+	 * We don't need to bother with changing PlaceHolderVars in the parent
+	 * query.  Their references to the RT index are still good for now, and
+	 * will get removed later if we're able to drop the RTE_RESULT.
+	 */
+
+	/*
+	 * Convert the RTE to be RTE_RESULT type, signifying that we don't need to
+	 * scan it anymore, and zero out RTE_FUNCTION-specific fields.  Also make
+	 * sure the RTE is not marked LATERAL, since elsewhere we don't expect
+	 * RTE_RESULTs to be LATERAL.
+	 */
+	rte->rtekind = RTE_RESULT;
+	rte->functions = NIL;
+	rte->lateral = false;
+
+	/*
+	 * We can reuse the RangeTblRef node.
+	 */
+	return jtnode;
+}
+
+/*
+ * is_simple_union_all
+ *	  Check a subquery to see if it's a simple UNION ALL.
+ *
+ * We require all the setops to be UNION ALL (no mixing) and there can't be
+ * any datatype coercions involved, ie, all the leaf queries must emit the
+ * same datatypes.
+ */
+static bool
+is_simple_union_all(Query *subquery)
+{
+	SetOperationStmt *topop;
+
+	/* Let's just make sure it's a valid subselect ... */
+	if (!IsA(subquery, Query) ||
+		subquery->commandType != CMD_SELECT)
+		elog(ERROR, "subquery is bogus");
+
+	/* Is it a set-operation query at all? */
+	topop = castNode(SetOperationStmt, subquery->setOperations);
+	if (!topop)
+		return false;
+
+	/* Can't handle ORDER BY, LIMIT/OFFSET, locking, or WITH */
+	if (subquery->sortClause ||
+		subquery->limitOffset ||
+		subquery->limitCount ||
+		subquery->rowMarks ||
+		subquery->cteList)
+		return false;
+
+	/* Recursively check the tree of set operations */
+	return is_simple_union_all_recurse((Node *) topop, subquery,
+									   topop->colTypes);
+}
+
+static bool
+is_simple_union_all_recurse(Node *setOp, Query *setOpQuery, List *colTypes)
+{
+	/* Since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
+	if (IsA(setOp, RangeTblRef))
+	{
+		RangeTblRef *rtr = (RangeTblRef *) setOp;
+		RangeTblEntry *rte = rt_fetch(rtr->rtindex, setOpQuery->rtable);
+		Query	   *subquery = rte->subquery;
+
+		Assert(subquery != NULL);
+
+		/* Leaf nodes are OK if they match the toplevel column types */
+		/* We don't have to compare typmods or collations here */
+		return tlist_same_datatypes(subquery->targetList, colTypes, true);
+	}
+	else if (IsA(setOp, SetOperationStmt))
+	{
+		SetOperationStmt *op = (SetOperationStmt *) setOp;
+
+		/* Must be UNION ALL */
+		if (op->op != SETOP_UNION || !op->all)
+			return false;
+
+		/* Recurse to check inputs */
+		return is_simple_union_all_recurse(op->larg, setOpQuery, colTypes) &&
+			is_simple_union_all_recurse(op->rarg, setOpQuery, colTypes);
+	}
+	else
+	{
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(setOp));
+		return false;			/* keep compiler quiet */
+	}
+}
+
+/*
+ * is_safe_append_member
+ *	  Check a subquery that is a leaf of a UNION ALL appendrel to see if it's
+ *	  safe to pull up.
+ */
+static bool
+is_safe_append_member(Query *subquery)
+{
+	FromExpr   *jtnode;
+
+	/*
+	 * It's only safe to pull up the child if its jointree contains exactly
+	 * one RTE, else the AppendRelInfo data structure breaks. The one base RTE
+	 * could be buried in several levels of FromExpr, however.  Also, if the
+	 * child's jointree is completely empty, we can pull up because
+	 * pull_up_simple_subquery will insert a single RTE_RESULT RTE instead.
+	 *
+	 * Also, the child can't have any WHERE quals because there's no place to
+	 * put them in an appendrel.  (This is a bit annoying...) If we didn't
+	 * need to check this, we'd just test whether get_relids_in_jointree()
+	 * yields a singleton set, to be more consistent with the coding of
+	 * fix_append_rel_relids().
+	 */
+	jtnode = subquery->jointree;
+	Assert(IsA(jtnode, FromExpr));
+	/* Check the completely-empty case */
+	if (jtnode->fromlist == NIL && jtnode->quals == NULL)
+		return true;
+	/* Check the more general case */
+	while (IsA(jtnode, FromExpr))
+	{
+		if (jtnode->quals != NULL)
+			return false;
+		if (list_length(jtnode->fromlist) != 1)
+			return false;
+		jtnode = linitial(jtnode->fromlist);
+	}
+	if (!IsA(jtnode, RangeTblRef))
+		return false;
+
+	return true;
+}
+
+/*
+ * jointree_contains_lateral_outer_refs
+ *		Check for disallowed lateral references in a jointree's quals
+ *
+ * If restricted is false, all level-1 Vars are allowed (but we still must
+ * search the jointree, since it might contain outer joins below which there
+ * will be restrictions).  If restricted is true, return true when any qual
+ * in the jointree contains level-1 Vars coming from outside the rels listed
+ * in safe_upper_varnos.
+ */
+static bool
+jointree_contains_lateral_outer_refs(PlannerInfo *root, Node *jtnode,
+									 bool restricted,
+									 Relids safe_upper_varnos)
+{
+	if (jtnode == NULL)
+		return false;
+	if (IsA(jtnode, RangeTblRef))
+		return false;
+	else if (IsA(jtnode, FromExpr))
+	{
+		FromExpr   *f = (FromExpr *) jtnode;
+		ListCell   *l;
+
+		/* First, recurse to check child joins */
+		foreach(l, f->fromlist)
+		{
+			if (jointree_contains_lateral_outer_refs(root,
+													 lfirst(l),
+													 restricted,
+													 safe_upper_varnos))
+				return true;
+		}
+
+		/* Then check the top-level quals */
+		if (restricted &&
+			!bms_is_subset(pull_varnos_of_level(root, f->quals, 1),
+						   safe_upper_varnos))
+			return true;
+	}
+	else if (IsA(jtnode, JoinExpr))
+	{
+		JoinExpr   *j = (JoinExpr *) jtnode;
+
+		/*
+		 * If this is an outer join, we mustn't allow any upper lateral
+		 * references in or below it.
+		 */
+		if (j->jointype != JOIN_INNER)
+		{
+			restricted = true;
+			safe_upper_varnos = NULL;
+		}
+
+		/* Check the child joins */
+		if (jointree_contains_lateral_outer_refs(root,
+												 j->larg,
+												 restricted,
+												 safe_upper_varnos))
+			return true;
+		if (jointree_contains_lateral_outer_refs(root,
+												 j->rarg,
+												 restricted,
+												 safe_upper_varnos))
+			return true;
+
+		/* Check the JOIN's qual clauses */
+		if (restricted &&
+			!bms_is_subset(pull_varnos_of_level(root, j->quals, 1),
+						   safe_upper_varnos))
+			return true;
+	}
+	else
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(jtnode));
+	return false;
+}
+
+/*
+ * Perform pullup_replace_vars everyplace it's needed in the query tree.
+ *
+ * Caller has already filled *rvcontext with data describing what to
+ * substitute for Vars referencing the target subquery.  In addition
+ * we need the identity of the lowest outer join that can null the
+ * target subquery, and its containing appendrel if any.
+ */
+static void
+perform_pullup_replace_vars(PlannerInfo *root,
+							pullup_replace_vars_context *rvcontext,
+							JoinExpr *lowest_nulling_outer_join,
+							AppendRelInfo *containing_appendrel)
+{
+	Query	   *parse = root->parse;
+	ListCell   *lc;
+
+	/*
+	 * Replace all of the top query's references to the subquery's outputs
+	 * with copies of the adjusted subtlist items, being careful not to
+	 * replace any of the jointree structure.  (This'd be a lot cleaner if we
+	 * could use query_tree_mutator.)  We have to use PHVs in the targetList,
+	 * returningList, and havingQual, since those are certainly above any
+	 * outer join.  replace_vars_in_jointree tracks its location in the
+	 * jointree and uses PHVs or not appropriately.
+	 */
+	parse->targetList = (List *)
+		pullup_replace_vars((Node *) parse->targetList, rvcontext);
+	parse->returningList = (List *)
+		pullup_replace_vars((Node *) parse->returningList, rvcontext);
+
+	foreach(lc, parse->windowClause)
+	{
+		WindowClause *wc = lfirst_node(WindowClause, lc);
+
+		if (wc->runCondition != NIL)
+			wc->runCondition = (List *)
+				pullup_replace_vars((Node *) wc->runCondition, rvcontext);
+	}
+	if (parse->onConflict)
+	{
+		parse->onConflict->onConflictSet = (List *)
+			pullup_replace_vars((Node *) parse->onConflict->onConflictSet,
+								rvcontext);
+		parse->onConflict->onConflictWhere =
+			pullup_replace_vars(parse->onConflict->onConflictWhere,
+								rvcontext);
+
+		/*
+		 * We assume ON CONFLICT's arbiterElems, arbiterWhere, exclRelTlist
+		 * can't contain any references to a subquery.
+		 */
+	}
+	if (parse->mergeActionList)
+	{
+		foreach(lc, parse->mergeActionList)
+		{
+			MergeAction *action = lfirst(lc);
+
+			action->qual = pullup_replace_vars(action->qual, rvcontext);
+			action->targetList = (List *)
+				pullup_replace_vars((Node *) action->targetList, rvcontext);
+		}
+	}
+	replace_vars_in_jointree((Node *) parse->jointree, rvcontext,
+							 lowest_nulling_outer_join);
+	Assert(parse->setOperations == NULL);
+	parse->havingQual = pullup_replace_vars(parse->havingQual, rvcontext);
+
+	/*
+	 * Replace references in the translated_vars lists of appendrels.  When
+	 * pulling up an appendrel member, we do not need PHVs in the list of the
+	 * parent appendrel --- there isn't any outer join between.  Elsewhere,
+	 * use PHVs for safety.  (This analysis could be made tighter but it seems
+	 * unlikely to be worth much trouble.)
+	 */
+	foreach(lc, root->append_rel_list)
+	{
+		AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(lc);
+		bool		save_need_phvs = rvcontext->need_phvs;
+
+		if (appinfo == containing_appendrel)
+			rvcontext->need_phvs = false;
+		appinfo->translated_vars = (List *)
+			pullup_replace_vars((Node *) appinfo->translated_vars, rvcontext);
+		rvcontext->need_phvs = save_need_phvs;
+	}
+
+	/*
+	 * Replace references in the joinaliasvars lists of join RTEs.
+	 *
+	 * You might think that we could avoid using PHVs for alias vars of joins
+	 * below lowest_nulling_outer_join, but that doesn't work because the
+	 * alias vars could be referenced above that join; we need the PHVs to be
+	 * present in such references after the alias vars get flattened.  (It
+	 * might be worth trying to be smarter here, someday.)
+	 */
+	foreach(lc, parse->rtable)
+	{
+		RangeTblEntry *otherrte = (RangeTblEntry *) lfirst(lc);
+
+		if (otherrte->rtekind == RTE_JOIN)
+			otherrte->joinaliasvars = (List *)
+				pullup_replace_vars((Node *) otherrte->joinaliasvars,
+									rvcontext);
+	}
+}
+
+/*
+ * Helper routine for perform_pullup_replace_vars: do pullup_replace_vars on
+ * every expression in the jointree, without changing the jointree structure
+ * itself.  Ugly, but there's no other way...
+ *
+ * If we are at or below lowest_nulling_outer_join, we can suppress use of
+ * PlaceHolderVars wrapped around the replacement expressions.
+ */
+static void
+replace_vars_in_jointree(Node *jtnode,
+						 pullup_replace_vars_context *context,
+						 JoinExpr *lowest_nulling_outer_join)
+{
+	if (jtnode == NULL)
+		return;
+	if (IsA(jtnode, RangeTblRef))
+	{
+		/*
+		 * If the RangeTblRef refers to a LATERAL subquery (that isn't the
+		 * same subquery we're pulling up), it might contain references to the
+		 * target subquery, which we must replace.  We drive this from the
+		 * jointree scan, rather than a scan of the rtable, for a couple of
+		 * reasons: we can avoid processing no-longer-referenced RTEs, and we
+		 * can use the appropriate setting of need_phvs depending on whether
+		 * the RTE is above possibly-nulling outer joins or not.
+		 */
+		int			varno = ((RangeTblRef *) jtnode)->rtindex;
+
+		if (varno != context->varno)	/* ignore target subquery itself */
+		{
+			RangeTblEntry *rte = rt_fetch(varno, context->root->parse->rtable);
+
+			Assert(rte != context->target_rte);
+			if (rte->lateral)
+			{
+				switch (rte->rtekind)
+				{
+					case RTE_RELATION:
+						/* shouldn't be marked LATERAL unless tablesample */
+						Assert(rte->tablesample);
+						rte->tablesample = (TableSampleClause *)
+							pullup_replace_vars((Node *) rte->tablesample,
+												context);
+						break;
+					case RTE_SUBQUERY:
+						rte->subquery =
+							pullup_replace_vars_subquery(rte->subquery,
+														 context);
+						break;
+					case RTE_FUNCTION:
+						rte->functions = (List *)
+							pullup_replace_vars((Node *) rte->functions,
+												context);
+						break;
+					case RTE_TABLEFUNC:
+						rte->tablefunc = (TableFunc *)
+							pullup_replace_vars((Node *) rte->tablefunc,
+												context);
+						break;
+					case RTE_VALUES:
+						rte->values_lists = (List *)
+							pullup_replace_vars((Node *) rte->values_lists,
+												context);
+						break;
+					case RTE_JOIN:
+					case RTE_CTE:
+					case RTE_NAMEDTUPLESTORE:
+					case RTE_RESULT:
+						/* these shouldn't be marked LATERAL */
+						Assert(false);
+						break;
+				}
+			}
+		}
+	}
+	else if (IsA(jtnode, FromExpr))
+	{
+		FromExpr   *f = (FromExpr *) jtnode;
+		ListCell   *l;
+
+		foreach(l, f->fromlist)
+			replace_vars_in_jointree(lfirst(l), context,
+									 lowest_nulling_outer_join);
+		f->quals = pullup_replace_vars(f->quals, context);
+	}
+	else if (IsA(jtnode, JoinExpr))
+	{
+		JoinExpr   *j = (JoinExpr *) jtnode;
+		bool		save_need_phvs = context->need_phvs;
+
+		if (j == lowest_nulling_outer_join)
+		{
+			/* no more PHVs in or below this join */
+			context->need_phvs = false;
+			lowest_nulling_outer_join = NULL;
+		}
+		replace_vars_in_jointree(j->larg, context, lowest_nulling_outer_join);
+		replace_vars_in_jointree(j->rarg, context, lowest_nulling_outer_join);
+
+		/*
+		 * Use PHVs within the join quals of a full join, even when it's the
+		 * lowest nulling outer join.  Otherwise, we cannot identify which
+		 * side of the join a pulled-up var-free expression came from, which
+		 * can lead to failure to make a plan at all because none of the quals
+		 * appear to be mergeable or hashable conditions.  For this purpose we
+		 * don't care about the state of wrap_non_vars, so leave it alone.
+		 */
+		if (j->jointype == JOIN_FULL)
+			context->need_phvs = true;
+
+		j->quals = pullup_replace_vars(j->quals, context);
+
+		/*
+		 * We don't bother to update the colvars list, since it won't be used
+		 * again ...
+		 */
+		context->need_phvs = save_need_phvs;
+	}
+	else
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(jtnode));
+}
+
+/*
+ * Apply pullup variable replacement throughout an expression tree
+ *
+ * Returns a modified copy of the tree, so this can't be used where we
+ * need to do in-place replacement.
+ */
+static Node *
+pullup_replace_vars(Node *expr, pullup_replace_vars_context *context)
+{
+	return replace_rte_variables(expr,
+								 context->varno, 0,
+								 pullup_replace_vars_callback,
+								 (void *) context,
+								 context->outer_hasSubLinks);
+}
+
+static Node *
+pullup_replace_vars_callback(Var *var,
+							 replace_rte_variables_context *context)
+{
+	pullup_replace_vars_context *rcon = (pullup_replace_vars_context *) context->callback_arg;
+	int			varattno = var->varattno;
+	Node	   *newnode;
+
+	/*
+	 * If PlaceHolderVars are needed, we cache the modified expressions in
+	 * rcon->rv_cache[].  This is not in hopes of any material speed gain
+	 * within this function, but to avoid generating identical PHVs with
+	 * different IDs.  That would result in duplicate evaluations at runtime,
+	 * and possibly prevent optimizations that rely on recognizing different
+	 * references to the same subquery output as being equal().  So it's worth
+	 * a bit of extra effort to avoid it.
+	 */
+	if (rcon->need_phvs &&
+		varattno >= InvalidAttrNumber &&
+		varattno <= list_length(rcon->targetlist) &&
+		rcon->rv_cache[varattno] != NULL)
+	{
+		/* Just copy the entry and fall through to adjust its varlevelsup */
+		newnode = copyObject(rcon->rv_cache[varattno]);
+	}
+	else if (varattno == InvalidAttrNumber)
+	{
+		/* Must expand whole-tuple reference into RowExpr */
+		RowExpr    *rowexpr;
+		List	   *colnames;
+		List	   *fields;
+		bool		save_need_phvs = rcon->need_phvs;
+		int			save_sublevelsup = context->sublevels_up;
+
+		/*
+		 * If generating an expansion for a var of a named rowtype (ie, this
+		 * is a plain relation RTE), then we must include dummy items for
+		 * dropped columns.  If the var is RECORD (ie, this is a JOIN), then
+		 * omit dropped columns.  In the latter case, attach column names to
+		 * the RowExpr for use of the executor and ruleutils.c.
+		 *
+		 * In order to be able to cache the results, we always generate the
+		 * expansion with varlevelsup = 0, and then adjust if needed.
+		 */
+		expandRTE(rcon->target_rte,
+				  var->varno, 0 /* not varlevelsup */ , var->location,
+				  (var->vartype != RECORDOID),
+				  &colnames, &fields);
+		/* Adjust the generated per-field Vars, but don't insert PHVs */
+		rcon->need_phvs = false;
+		context->sublevels_up = 0;	/* to match the expandRTE output */
+		fields = (List *) replace_rte_variables_mutator((Node *) fields,
+														context);
+		rcon->need_phvs = save_need_phvs;
+		context->sublevels_up = save_sublevelsup;
+
+		rowexpr = makeNode(RowExpr);
+		rowexpr->args = fields;
+		rowexpr->row_typeid = var->vartype;
+		rowexpr->row_format = COERCE_IMPLICIT_CAST;
+		rowexpr->colnames = (var->vartype == RECORDOID) ? colnames : NIL;
+		rowexpr->location = var->location;
+		newnode = (Node *) rowexpr;
+
+		/*
+		 * Insert PlaceHolderVar if needed.  Notice that we are wrapping one
+		 * PlaceHolderVar around the whole RowExpr, rather than putting one
+		 * around each element of the row.  This is because we need the
+		 * expression to yield NULL, not ROW(NULL,NULL,...) when it is forced
+		 * to null by an outer join.
+		 */
+		if (rcon->need_phvs)
+		{
+			/* RowExpr is certainly not strict, so always need PHV */
+			newnode = (Node *)
+				make_placeholder_expr(rcon->root,
+									  (Expr *) newnode,
+									  bms_make_singleton(rcon->varno));
+			/* cache it with the PHV, and with varlevelsup still zero */
+			rcon->rv_cache[InvalidAttrNumber] = copyObject(newnode);
+		}
+	}
+	else
+	{
+		/* Normal case referencing one targetlist element */
+		TargetEntry *tle = get_tle_by_resno(rcon->targetlist, varattno);
+
+		if (tle == NULL)		/* shouldn't happen */
+			elog(ERROR, "could not find attribute %d in subquery targetlist",
+				 varattno);
+
+		/* Make a copy of the tlist item to return */
+		newnode = (Node *) copyObject(tle->expr);
+
+		/* Insert PlaceHolderVar if needed */
+		if (rcon->need_phvs)
+		{
+			bool		wrap;
+
+			if (newnode && IsA(newnode, Var) &&
+				((Var *) newnode)->varlevelsup == 0)
+			{
+				/*
+				 * Simple Vars always escape being wrapped, unless they are
+				 * lateral references to something outside the subquery being
+				 * pulled up.  (Even then, we could omit the PlaceHolderVar if
+				 * the referenced rel is under the same lowest outer join, but
+				 * it doesn't seem worth the trouble to check that.)
+				 */
+				if (rcon->target_rte->lateral &&
+					!bms_is_member(((Var *) newnode)->varno, rcon->relids))
+					wrap = true;
+				else
+					wrap = false;
+			}
+			else if (newnode && IsA(newnode, PlaceHolderVar) &&
+					 ((PlaceHolderVar *) newnode)->phlevelsup == 0)
+			{
+				/* No need to wrap a PlaceHolderVar with another one, either */
+				wrap = false;
+			}
+			else if (rcon->wrap_non_vars)
+			{
+				/* Wrap all non-Vars in a PlaceHolderVar */
+				wrap = true;
+			}
+			else
+			{
+				/*
+				 * If it contains a Var of the subquery being pulled up, and
+				 * does not contain any non-strict constructs, then it's
+				 * certainly nullable so we don't need to insert a
+				 * PlaceHolderVar.
+				 *
+				 * This analysis could be tighter: in particular, a non-strict
+				 * construct hidden within a lower-level PlaceHolderVar is not
+				 * reason to add another PHV.  But for now it doesn't seem
+				 * worth the code to be more exact.
+				 *
+				 * Note: in future maybe we should insert a PlaceHolderVar
+				 * anyway, if the tlist item is expensive to evaluate?
+				 *
+				 * For a LATERAL subquery, we have to check the actual var
+				 * membership of the node, but if it's non-lateral then any
+				 * level-zero var must belong to the subquery.
+				 */
+				if ((rcon->target_rte->lateral ?
+					 bms_overlap(pull_varnos(rcon->root, (Node *) newnode),
+								 rcon->relids) :
+					 contain_vars_of_level((Node *) newnode, 0)) &&
+					!contain_nonstrict_functions((Node *) newnode))
+				{
+					/* No wrap needed */
+					wrap = false;
+				}
+				else
+				{
+					/* Else wrap it in a PlaceHolderVar */
+					wrap = true;
+				}
+			}
+
+			if (wrap)
+				newnode = (Node *)
+					make_placeholder_expr(rcon->root,
+										  (Expr *) newnode,
+										  bms_make_singleton(rcon->varno));
+
+			/*
+			 * Cache it if possible (ie, if the attno is in range, which it
+			 * probably always should be).  We can cache the value even if we
+			 * decided we didn't need a PHV, since this result will be
+			 * suitable for any request that has need_phvs.
+			 */
+			if (varattno > InvalidAttrNumber &&
+				varattno <= list_length(rcon->targetlist))
+				rcon->rv_cache[varattno] = copyObject(newnode);
+		}
+	}
+
+	/* Must adjust varlevelsup if tlist item is from higher query */
+	if (var->varlevelsup > 0)
+		IncrementVarSublevelsUp(newnode, var->varlevelsup, 0);
+
+	return newnode;
+}
+
+/*
+ * Apply pullup variable replacement to a subquery
+ *
+ * This needs to be different from pullup_replace_vars() because
+ * replace_rte_variables will think that it shouldn't increment sublevels_up
+ * before entering the Query; so we need to call it with sublevels_up == 1.
+ */
+static Query *
+pullup_replace_vars_subquery(Query *query,
+							 pullup_replace_vars_context *context)
+{
+	Assert(IsA(query, Query));
+	return (Query *) replace_rte_variables((Node *) query,
+										   context->varno, 1,
+										   pullup_replace_vars_callback,
+										   (void *) context,
+										   NULL);
+}
+
+
+/*
+ * flatten_simple_union_all
+ *		Try to optimize top-level UNION ALL structure into an appendrel
+ *
+ * If a query's setOperations tree consists entirely of simple UNION ALL
+ * operations, flatten it into an append relation, which we can process more
+ * intelligently than the general setops case.  Otherwise, do nothing.
+ *
+ * In most cases, this can succeed only for a top-level query, because for a
+ * subquery in FROM, the parent query's invocation of pull_up_subqueries would
+ * already have flattened the UNION via pull_up_simple_union_all.  But there
+ * are a few cases we can support here but not in that code path, for example
+ * when the subquery also contains ORDER BY.
+ */
+void
+flatten_simple_union_all(PlannerInfo *root)
+{
+	Query	   *parse = root->parse;
+	SetOperationStmt *topop;
+	Node	   *leftmostjtnode;
+	int			leftmostRTI;
+	RangeTblEntry *leftmostRTE;
+	int			childRTI;
+	RangeTblEntry *childRTE;
+	RangeTblRef *rtr;
+
+	/* Shouldn't be called unless query has setops */
+	topop = castNode(SetOperationStmt, parse->setOperations);
+	Assert(topop);
+
+	/* Can't optimize away a recursive UNION */
+	if (root->hasRecursion)
+		return;
+
+	/*
+	 * Recursively check the tree of set operations.  If not all UNION ALL
+	 * with identical column types, punt.
+	 */
+	if (!is_simple_union_all_recurse((Node *) topop, parse, topop->colTypes))
+		return;
+
+	/*
+	 * Locate the leftmost leaf query in the setops tree.  The upper query's
+	 * Vars all refer to this RTE (see transformSetOperationStmt).
+	 */
+	leftmostjtnode = topop->larg;
+	while (leftmostjtnode && IsA(leftmostjtnode, SetOperationStmt))
+		leftmostjtnode = ((SetOperationStmt *) leftmostjtnode)->larg;
+	Assert(leftmostjtnode && IsA(leftmostjtnode, RangeTblRef));
+	leftmostRTI = ((RangeTblRef *) leftmostjtnode)->rtindex;
+	leftmostRTE = rt_fetch(leftmostRTI, parse->rtable);
+	Assert(leftmostRTE->rtekind == RTE_SUBQUERY);
+
+	/*
+	 * Make a copy of the leftmost RTE and add it to the rtable.  This copy
+	 * will represent the leftmost leaf query in its capacity as a member of
+	 * the appendrel.  The original will represent the appendrel as a whole.
+	 * (We must do things this way because the upper query's Vars have to be
+	 * seen as referring to the whole appendrel.)
+	 */
+	childRTE = copyObject(leftmostRTE);
+	parse->rtable = lappend(parse->rtable, childRTE);
+	childRTI = list_length(parse->rtable);
+
+	/* Modify the setops tree to reference the child copy */
+	((RangeTblRef *) leftmostjtnode)->rtindex = childRTI;
+
+	/* Modify the formerly-leftmost RTE to mark it as an appendrel parent */
+	leftmostRTE->inh = true;
+
+	/*
+	 * Form a RangeTblRef for the appendrel, and insert it into FROM.  The top
+	 * Query of a setops tree should have had an empty FromClause initially.
+	 */
+	rtr = makeNode(RangeTblRef);
+	rtr->rtindex = leftmostRTI;
+	Assert(parse->jointree->fromlist == NIL);
+	parse->jointree->fromlist = list_make1(rtr);
+
+	/*
+	 * Now pretend the query has no setops.  We must do this before trying to
+	 * do subquery pullup, because of Assert in pull_up_simple_subquery.
+	 */
+	parse->setOperations = NULL;
+
+	/*
+	 * Build AppendRelInfo information, and apply pull_up_subqueries to the
+	 * leaf queries of the UNION ALL.  (We must do that now because they
+	 * weren't previously referenced by the jointree, and so were missed by
+	 * the main invocation of pull_up_subqueries.)
+	 */
+	pull_up_union_leaf_queries((Node *) topop, root, leftmostRTI, parse, 0);
+}
+
+
+/*
+ * reduce_outer_joins
+ *		Attempt to reduce outer joins to plain inner joins.
+ *
+ * The idea here is that given a query like
+ *		SELECT ... FROM a LEFT JOIN b ON (...) WHERE b.y = 42;
+ * we can reduce the LEFT JOIN to a plain JOIN if the "=" operator in WHERE
+ * is strict.  The strict operator will always return NULL, causing the outer
+ * WHERE to fail, on any row where the LEFT JOIN filled in NULLs for b's
+ * columns.  Therefore, there's no need for the join to produce null-extended
+ * rows in the first place --- which makes it a plain join not an outer join.
+ * (This scenario may not be very likely in a query written out by hand, but
+ * it's reasonably likely when pushing quals down into complex views.)
+ *
+ * More generally, an outer join can be reduced in strength if there is a
+ * strict qual above it in the qual tree that constrains a Var from the
+ * nullable side of the join to be non-null.  (For FULL joins this applies
+ * to each side separately.)
+ *
+ * Another transformation we apply here is to recognize cases like
+ *		SELECT ... FROM a LEFT JOIN b ON (a.x = b.y) WHERE b.y IS NULL;
+ * If the join clause is strict for b.y, then only null-extended rows could
+ * pass the upper WHERE, and we can conclude that what the query is really
+ * specifying is an anti-semijoin.  We change the join type from JOIN_LEFT
+ * to JOIN_ANTI.  The IS NULL clause then becomes redundant, and must be
+ * removed to prevent bogus selectivity calculations, but we leave it to
+ * distribute_qual_to_rels to get rid of such clauses.
+ *
+ * Also, we get rid of JOIN_RIGHT cases by flipping them around to become
+ * JOIN_LEFT.  This saves some code here and in some later planner routines,
+ * but the main reason to do it is to not need to invent a JOIN_REVERSE_ANTI
+ * join type.
+ *
+ * To ease recognition of strict qual clauses, we require this routine to be
+ * run after expression preprocessing (i.e., qual canonicalization and JOIN
+ * alias-var expansion).
+ */
+void
+reduce_outer_joins(PlannerInfo *root)
+{
+	reduce_outer_joins_state *state;
+
+	/*
+	 * To avoid doing strictness checks on more quals than necessary, we want
+	 * to stop descending the jointree as soon as there are no outer joins
+	 * below our current point.  This consideration forces a two-pass process.
+	 * The first pass gathers information about which base rels appear below
+	 * each side of each join clause, and about whether there are outer
+	 * join(s) below each side of each join clause. The second pass examines
+	 * qual clauses and changes join types as it descends the tree.
+	 */
+	state = reduce_outer_joins_pass1((Node *) root->parse->jointree);
+
+	/* planner.c shouldn't have called me if no outer joins */
+	if (state == NULL || !state->contains_outer)
+		elog(ERROR, "so where are the outer joins?");
+
+	reduce_outer_joins_pass2((Node *) root->parse->jointree,
+							 state, root, NULL, NIL, NIL);
+}
+
+/*
+ * reduce_outer_joins_pass1 - phase 1 data collection
+ *
+ * Returns a state node describing the given jointree node.
+ */
+static reduce_outer_joins_state *
+reduce_outer_joins_pass1(Node *jtnode)
+{
+	reduce_outer_joins_state *result;
+
+	result = (reduce_outer_joins_state *)
+		palloc(sizeof(reduce_outer_joins_state));
+	result->relids = NULL;
+	result->contains_outer = false;
+	result->sub_states = NIL;
+
+	if (jtnode == NULL)
+		return result;
+	if (IsA(jtnode, RangeTblRef))
+	{
+		int			varno = ((RangeTblRef *) jtnode)->rtindex;
+
+		result->relids = bms_make_singleton(varno);
+	}
+	else if (IsA(jtnode, FromExpr))
+	{
+		FromExpr   *f = (FromExpr *) jtnode;
+		ListCell   *l;
+
+		foreach(l, f->fromlist)
+		{
+			reduce_outer_joins_state *sub_state;
+
+			sub_state = reduce_outer_joins_pass1(lfirst(l));
+			result->relids = bms_add_members(result->relids,
+											 sub_state->relids);
+			result->contains_outer |= sub_state->contains_outer;
+			result->sub_states = lappend(result->sub_states, sub_state);
+		}
+	}
+	else if (IsA(jtnode, JoinExpr))
+	{
+		JoinExpr   *j = (JoinExpr *) jtnode;
+		reduce_outer_joins_state *sub_state;
+
+		/* join's own RT index is not wanted in result->relids */
+		if (IS_OUTER_JOIN(j->jointype))
+			result->contains_outer = true;
+
+		sub_state = reduce_outer_joins_pass1(j->larg);
+		result->relids = bms_add_members(result->relids,
+										 sub_state->relids);
+		result->contains_outer |= sub_state->contains_outer;
+		result->sub_states = lappend(result->sub_states, sub_state);
+
+		sub_state = reduce_outer_joins_pass1(j->rarg);
+		result->relids = bms_add_members(result->relids,
+										 sub_state->relids);
+		result->contains_outer |= sub_state->contains_outer;
+		result->sub_states = lappend(result->sub_states, sub_state);
+	}
+	else
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(jtnode));
+	return result;
+}
+
+/*
+ * reduce_outer_joins_pass2 - phase 2 processing
+ *
+ *	jtnode: current jointree node
+ *	state: state data collected by phase 1 for this node
+ *	root: toplevel planner state
+ *	nonnullable_rels: set of base relids forced non-null by upper quals
+ *	nonnullable_vars: list of Vars forced non-null by upper quals
+ *	forced_null_vars: list of Vars forced null by upper quals
+ */
+static void
+reduce_outer_joins_pass2(Node *jtnode,
+						 reduce_outer_joins_state *state,
+						 PlannerInfo *root,
+						 Relids nonnullable_rels,
+						 List *nonnullable_vars,
+						 List *forced_null_vars)
+{
+	/*
+	 * pass 2 should never descend as far as an empty subnode or base rel,
+	 * because it's only called on subtrees marked as contains_outer.
+	 */
+	if (jtnode == NULL)
+		elog(ERROR, "reached empty jointree");
+	if (IsA(jtnode, RangeTblRef))
+		elog(ERROR, "reached base rel");
+	else if (IsA(jtnode, FromExpr))
+	{
+		FromExpr   *f = (FromExpr *) jtnode;
+		ListCell   *l;
+		ListCell   *s;
+		Relids		pass_nonnullable_rels;
+		List	   *pass_nonnullable_vars;
+		List	   *pass_forced_null_vars;
+
+		/* Scan quals to see if we can add any constraints */
+		pass_nonnullable_rels = find_nonnullable_rels(f->quals);
+		pass_nonnullable_rels = bms_add_members(pass_nonnullable_rels,
+												nonnullable_rels);
+		pass_nonnullable_vars = find_nonnullable_vars(f->quals);
+		pass_nonnullable_vars = list_concat(pass_nonnullable_vars,
+											nonnullable_vars);
+		pass_forced_null_vars = find_forced_null_vars(f->quals);
+		pass_forced_null_vars = list_concat(pass_forced_null_vars,
+											forced_null_vars);
+		/* And recurse --- but only into interesting subtrees */
+		Assert(list_length(f->fromlist) == list_length(state->sub_states));
+		forboth(l, f->fromlist, s, state->sub_states)
+		{
+			reduce_outer_joins_state *sub_state = lfirst(s);
+
+			if (sub_state->contains_outer)
+				reduce_outer_joins_pass2(lfirst(l), sub_state, root,
+										 pass_nonnullable_rels,
+										 pass_nonnullable_vars,
+										 pass_forced_null_vars);
+		}
+		bms_free(pass_nonnullable_rels);
+		/* can't so easily clean up var lists, unfortunately */
+	}
+	else if (IsA(jtnode, JoinExpr))
+	{
+		JoinExpr   *j = (JoinExpr *) jtnode;
+		int			rtindex = j->rtindex;
+		JoinType	jointype = j->jointype;
+		reduce_outer_joins_state *left_state = linitial(state->sub_states);
+		reduce_outer_joins_state *right_state = lsecond(state->sub_states);
+		List	   *local_nonnullable_vars = NIL;
+		bool		computed_local_nonnullable_vars = false;
+
+		/* Can we simplify this join? */
+		switch (jointype)
+		{
+			case JOIN_INNER:
+				break;
+			case JOIN_LEFT:
+				if (bms_overlap(nonnullable_rels, right_state->relids))
+					jointype = JOIN_INNER;
+				break;
+			case JOIN_RIGHT:
+				if (bms_overlap(nonnullable_rels, left_state->relids))
+					jointype = JOIN_INNER;
+				break;
+			case JOIN_FULL:
+				if (bms_overlap(nonnullable_rels, left_state->relids))
+				{
+					if (bms_overlap(nonnullable_rels, right_state->relids))
+						jointype = JOIN_INNER;
+					else
+						jointype = JOIN_LEFT;
+				}
+				else
+				{
+					if (bms_overlap(nonnullable_rels, right_state->relids))
+						jointype = JOIN_RIGHT;
+				}
+				break;
+			case JOIN_SEMI:
+			case JOIN_ANTI:
+
+				/*
+				 * These could only have been introduced by pull_up_sublinks,
+				 * so there's no way that upper quals could refer to their
+				 * righthand sides, and no point in checking.
+				 */
+				break;
+			default:
+				elog(ERROR, "unrecognized join type: %d",
+					 (int) jointype);
+				break;
+		}
+
+		/*
+		 * Convert JOIN_RIGHT to JOIN_LEFT.  Note that in the case where we
+		 * reduced JOIN_FULL to JOIN_RIGHT, this will mean the JoinExpr no
+		 * longer matches the internal ordering of any CoalesceExpr's built to
+		 * represent merged join variables.  We don't care about that at
+		 * present, but be wary of it ...
+		 */
+		if (jointype == JOIN_RIGHT)
+		{
+			Node	   *tmparg;
+
+			tmparg = j->larg;
+			j->larg = j->rarg;
+			j->rarg = tmparg;
+			jointype = JOIN_LEFT;
+			right_state = linitial(state->sub_states);
+			left_state = lsecond(state->sub_states);
+		}
+
+		/*
+		 * See if we can reduce JOIN_LEFT to JOIN_ANTI.  This is the case if
+		 * the join's own quals are strict for any var that was forced null by
+		 * higher qual levels.  NOTE: there are other ways that we could
+		 * detect an anti-join, in particular if we were to check whether Vars
+		 * coming from the RHS must be non-null because of table constraints.
+		 * That seems complicated and expensive though (in particular, one
+		 * would have to be wary of lower outer joins). For the moment this
+		 * seems sufficient.
+		 */
+		if (jointype == JOIN_LEFT)
+		{
+			List	   *overlap;
+
+			local_nonnullable_vars = find_nonnullable_vars(j->quals);
+			computed_local_nonnullable_vars = true;
+
+			/*
+			 * It's not sufficient to check whether local_nonnullable_vars and
+			 * forced_null_vars overlap: we need to know if the overlap
+			 * includes any RHS variables.
+			 */
+			overlap = list_intersection(local_nonnullable_vars,
+										forced_null_vars);
+			if (overlap != NIL &&
+				bms_overlap(pull_varnos(root, (Node *) overlap),
+							right_state->relids))
+				jointype = JOIN_ANTI;
+		}
+
+		/* Apply the jointype change, if any, to both jointree node and RTE */
+		if (rtindex && jointype != j->jointype)
+		{
+			RangeTblEntry *rte = rt_fetch(rtindex, root->parse->rtable);
+
+			Assert(rte->rtekind == RTE_JOIN);
+			Assert(rte->jointype == j->jointype);
+			rte->jointype = jointype;
+		}
+		j->jointype = jointype;
+
+		/* Only recurse if there's more to do below here */
+		if (left_state->contains_outer || right_state->contains_outer)
+		{
+			Relids		local_nonnullable_rels;
+			List	   *local_forced_null_vars;
+			Relids		pass_nonnullable_rels;
+			List	   *pass_nonnullable_vars;
+			List	   *pass_forced_null_vars;
+
+			/*
+			 * If this join is (now) inner, we can add any constraints its
+			 * quals provide to those we got from above.  But if it is outer,
+			 * we can pass down the local constraints only into the nullable
+			 * side, because an outer join never eliminates any rows from its
+			 * non-nullable side.  Also, there is no point in passing upper
+			 * constraints into the nullable side, since if there were any
+			 * we'd have been able to reduce the join.  (In the case of upper
+			 * forced-null constraints, we *must not* pass them into the
+			 * nullable side --- they either applied here, or not.) The upshot
+			 * is that we pass either the local or the upper constraints,
+			 * never both, to the children of an outer join.
+			 *
+			 * Note that a SEMI join works like an inner join here: it's okay
+			 * to pass down both local and upper constraints.  (There can't be
+			 * any upper constraints affecting its inner side, but it's not
+			 * worth having a separate code path to avoid passing them.)
+			 *
+			 * At a FULL join we just punt and pass nothing down --- is it
+			 * possible to be smarter?
+			 */
+			if (jointype != JOIN_FULL)
+			{
+				local_nonnullable_rels = find_nonnullable_rels(j->quals);
+				if (!computed_local_nonnullable_vars)
+					local_nonnullable_vars = find_nonnullable_vars(j->quals);
+				local_forced_null_vars = find_forced_null_vars(j->quals);
+				if (jointype == JOIN_INNER || jointype == JOIN_SEMI)
+				{
+					/* OK to merge upper and local constraints */
+					local_nonnullable_rels = bms_add_members(local_nonnullable_rels,
+															 nonnullable_rels);
+					local_nonnullable_vars = list_concat(local_nonnullable_vars,
+														 nonnullable_vars);
+					local_forced_null_vars = list_concat(local_forced_null_vars,
+														 forced_null_vars);
+				}
+			}
+			else
+			{
+				/* no use in calculating these */
+				local_nonnullable_rels = NULL;
+				local_forced_null_vars = NIL;
+			}
+
+			if (left_state->contains_outer)
+			{
+				if (jointype == JOIN_INNER || jointype == JOIN_SEMI)
+				{
+					/* pass union of local and upper constraints */
+					pass_nonnullable_rels = local_nonnullable_rels;
+					pass_nonnullable_vars = local_nonnullable_vars;
+					pass_forced_null_vars = local_forced_null_vars;
+				}
+				else if (jointype != JOIN_FULL) /* ie, LEFT or ANTI */
+				{
+					/* can't pass local constraints to non-nullable side */
+					pass_nonnullable_rels = nonnullable_rels;
+					pass_nonnullable_vars = nonnullable_vars;
+					pass_forced_null_vars = forced_null_vars;
+				}
+				else
+				{
+					/* no constraints pass through JOIN_FULL */
+					pass_nonnullable_rels = NULL;
+					pass_nonnullable_vars = NIL;
+					pass_forced_null_vars = NIL;
+				}
+				reduce_outer_joins_pass2(j->larg, left_state, root,
+										 pass_nonnullable_rels,
+										 pass_nonnullable_vars,
+										 pass_forced_null_vars);
+			}
+
+			if (right_state->contains_outer)
+			{
+				if (jointype != JOIN_FULL)	/* ie, INNER/LEFT/SEMI/ANTI */
+				{
+					/* pass appropriate constraints, per comment above */
+					pass_nonnullable_rels = local_nonnullable_rels;
+					pass_nonnullable_vars = local_nonnullable_vars;
+					pass_forced_null_vars = local_forced_null_vars;
+				}
+				else
+				{
+					/* no constraints pass through JOIN_FULL */
+					pass_nonnullable_rels = NULL;
+					pass_nonnullable_vars = NIL;
+					pass_forced_null_vars = NIL;
+				}
+				reduce_outer_joins_pass2(j->rarg, right_state, root,
+										 pass_nonnullable_rels,
+										 pass_nonnullable_vars,
+										 pass_forced_null_vars);
+			}
+			bms_free(local_nonnullable_rels);
+		}
+	}
+	else
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(jtnode));
+}
+
+
+/*
+ * remove_useless_result_rtes
+ *		Attempt to remove RTE_RESULT RTEs from the join tree.
+ *
+ * We can remove RTE_RESULT entries from the join tree using the knowledge
+ * that RTE_RESULT returns exactly one row and has no output columns.  Hence,
+ * if one is inner-joined to anything else, we can delete it.  Optimizations
+ * are also possible for some outer-join cases, as detailed below.
+ *
+ * Some of these optimizations depend on recognizing empty (constant-true)
+ * quals for FromExprs and JoinExprs.  That makes it useful to apply this
+ * optimization pass after expression preprocessing, since that will have
+ * eliminated constant-true quals, allowing more cases to be recognized as
+ * optimizable.  What's more, the usual reason for an RTE_RESULT to be present
+ * is that we pulled up a subquery or VALUES clause, thus very possibly
+ * replacing Vars with constants, making it more likely that a qual can be
+ * reduced to constant true.  Also, because some optimizations depend on
+ * the outer-join type, it's best to have done reduce_outer_joins() first.
+ *
+ * A PlaceHolderVar referencing an RTE_RESULT RTE poses an obstacle to this
+ * process: we must remove the RTE_RESULT's relid from the PHV's phrels, but
+ * we must not reduce the phrels set to empty.  If that would happen, and
+ * the RTE_RESULT is an immediate child of an outer join, we have to give up
+ * and not remove the RTE_RESULT: there is noplace else to evaluate the
+ * PlaceHolderVar.  (That is, in such cases the RTE_RESULT *does* have output
+ * columns.)  But if the RTE_RESULT is an immediate child of an inner join,
+ * we can usually change the PlaceHolderVar's phrels so as to evaluate it at
+ * the inner join instead.  This is OK because we really only care that PHVs
+ * are evaluated above or below the correct outer joins.  We can't, however,
+ * postpone the evaluation of a PHV to above where it is used; so there are
+ * some checks below on whether output PHVs are laterally referenced in the
+ * other join input rel(s).
+ *
+ * We used to try to do this work as part of pull_up_subqueries() where the
+ * potentially-optimizable cases get introduced; but it's way simpler, and
+ * more effective, to do it separately.
+ */
+void
+remove_useless_result_rtes(PlannerInfo *root)
+{
+	ListCell   *cell;
+
+	/* Top level of jointree must always be a FromExpr */
+	Assert(IsA(root->parse->jointree, FromExpr));
+	/* Recurse ... */
+	root->parse->jointree = (FromExpr *)
+		remove_useless_results_recurse(root, (Node *) root->parse->jointree);
+	/* We should still have a FromExpr */
+	Assert(IsA(root->parse->jointree, FromExpr));
+
+	/*
+	 * Remove any PlanRowMark referencing an RTE_RESULT RTE.  We obviously
+	 * must do that for any RTE_RESULT that we just removed.  But one for a
+	 * RTE that we did not remove can be dropped anyway: since the RTE has
+	 * only one possible output row, there is no need for EPQ to mark and
+	 * restore that row.
+	 *
+	 * It's necessary, not optional, to remove the PlanRowMark for a surviving
+	 * RTE_RESULT RTE; otherwise we'll generate a whole-row Var for the
+	 * RTE_RESULT, which the executor has no support for.
+	 */
+	foreach(cell, root->rowMarks)
+	{
+		PlanRowMark *rc = (PlanRowMark *) lfirst(cell);
+
+		if (rt_fetch(rc->rti, root->parse->rtable)->rtekind == RTE_RESULT)
+			root->rowMarks = foreach_delete_current(root->rowMarks, cell);
+	}
+}
+
+/*
+ * remove_useless_results_recurse
+ *		Recursive guts of remove_useless_result_rtes.
+ *
+ * This recursively processes the jointree and returns a modified jointree.
+ */
+static Node *
+remove_useless_results_recurse(PlannerInfo *root, Node *jtnode)
+{
+	Assert(jtnode != NULL);
+	if (IsA(jtnode, RangeTblRef))
+	{
+		/* Can't immediately do anything with a RangeTblRef */
+	}
+	else if (IsA(jtnode, FromExpr))
+	{
+		FromExpr   *f = (FromExpr *) jtnode;
+		Relids		result_relids = NULL;
+		ListCell   *cell;
+
+		/*
+		 * We can drop RTE_RESULT rels from the fromlist so long as at least
+		 * one child remains, since joining to a one-row table changes
+		 * nothing.  (But we can't drop a RTE_RESULT that computes PHV(s) that
+		 * are needed by some sibling.  The cleanup transformation below would
+		 * reassign the PHVs to be computed at the join, which is too late for
+		 * the sibling's use.)  The easiest way to mechanize this rule is to
+		 * modify the list in-place.
+		 */
+		foreach(cell, f->fromlist)
+		{
+			Node	   *child = (Node *) lfirst(cell);
+			int			varno;
+
+			/* Recursively transform child ... */
+			child = remove_useless_results_recurse(root, child);
+			/* ... and stick it back into the tree */
+			lfirst(cell) = child;
+
+			/*
+			 * If it's an RTE_RESULT with at least one sibling, and no sibling
+			 * references dependent PHVs, we can drop it.  We don't yet know
+			 * what the inner join's final relid set will be, so postpone
+			 * cleanup of PHVs etc till after this loop.
+			 */
+			if (list_length(f->fromlist) > 1 &&
+				(varno = get_result_relid(root, child)) != 0 &&
+				!find_dependent_phvs_in_jointree(root, (Node *) f, varno))
+			{
+				f->fromlist = foreach_delete_current(f->fromlist, cell);
+				result_relids = bms_add_member(result_relids, varno);
+			}
+		}
+
+		/*
+		 * Clean up if we dropped any RTE_RESULT RTEs.  This is a bit
+		 * inefficient if there's more than one, but it seems better to
+		 * optimize the support code for the single-relid case.
+		 */
+		if (result_relids)
+		{
+			int			varno = -1;
+
+			while ((varno = bms_next_member(result_relids, varno)) >= 0)
+				remove_result_refs(root, varno, (Node *) f);
+		}
+
+		/*
+		 * If we're not at the top of the jointree, it's valid to simplify a
+		 * degenerate FromExpr into its single child.  (At the top, we must
+		 * keep the FromExpr since Query.jointree is required to point to a
+		 * FromExpr.)
+		 */
+		if (f != root->parse->jointree &&
+			f->quals == NULL &&
+			list_length(f->fromlist) == 1)
+			return (Node *) linitial(f->fromlist);
+	}
+	else if (IsA(jtnode, JoinExpr))
+	{
+		JoinExpr   *j = (JoinExpr *) jtnode;
+		int			varno;
+
+		/* First, recurse */
+		j->larg = remove_useless_results_recurse(root, j->larg);
+		j->rarg = remove_useless_results_recurse(root, j->rarg);
+
+		/* Apply join-type-specific optimization rules */
+		switch (j->jointype)
+		{
+			case JOIN_INNER:
+
+				/*
+				 * An inner join is equivalent to a FromExpr, so if either
+				 * side was simplified to an RTE_RESULT rel, we can replace
+				 * the join with a FromExpr with just the other side; and if
+				 * the qual is empty (JOIN ON TRUE) then we can omit the
+				 * FromExpr as well.
+				 *
+				 * Just as in the FromExpr case, we can't simplify if the
+				 * other input rel references any PHVs that are marked as to
+				 * be evaluated at the RTE_RESULT rel, because we can't
+				 * postpone their evaluation in that case.  But we only have
+				 * to check this in cases where it's syntactically legal for
+				 * the other input to have a LATERAL reference to the
+				 * RTE_RESULT rel.  Only RHSes of inner and left joins are
+				 * allowed to have such refs.
+				 */
+				if ((varno = get_result_relid(root, j->larg)) != 0 &&
+					!find_dependent_phvs_in_jointree(root, j->rarg, varno))
+				{
+					remove_result_refs(root, varno, j->rarg);
+					if (j->quals)
+						jtnode = (Node *)
+							makeFromExpr(list_make1(j->rarg), j->quals);
+					else
+						jtnode = j->rarg;
+				}
+				else if ((varno = get_result_relid(root, j->rarg)) != 0)
+				{
+					remove_result_refs(root, varno, j->larg);
+					if (j->quals)
+						jtnode = (Node *)
+							makeFromExpr(list_make1(j->larg), j->quals);
+					else
+						jtnode = j->larg;
+				}
+				break;
+			case JOIN_LEFT:
+
+				/*
+				 * We can simplify this case if the RHS is an RTE_RESULT, with
+				 * two different possibilities:
+				 *
+				 * If the qual is empty (JOIN ON TRUE), then the join can be
+				 * strength-reduced to a plain inner join, since each LHS row
+				 * necessarily has exactly one join partner.  So we can always
+				 * discard the RHS, much as in the JOIN_INNER case above.
+				 * (Again, the LHS could not contain a lateral reference to
+				 * the RHS.)
+				 *
+				 * Otherwise, it's still true that each LHS row should be
+				 * returned exactly once, and since the RHS returns no columns
+				 * (unless there are PHVs that have to be evaluated there), we
+				 * don't much care if it's null-extended or not.  So in this
+				 * case also, we can just ignore the qual and discard the left
+				 * join.
+				 */
+				if ((varno = get_result_relid(root, j->rarg)) != 0 &&
+					(j->quals == NULL ||
+					 !find_dependent_phvs(root, varno)))
+				{
+					remove_result_refs(root, varno, j->larg);
+					jtnode = j->larg;
+				}
+				break;
+			case JOIN_SEMI:
+
+				/*
+				 * We may simplify this case if the RHS is an RTE_RESULT; the
+				 * join qual becomes effectively just a filter qual for the
+				 * LHS, since we should either return the LHS row or not.  For
+				 * simplicity we inject the filter qual into a new FromExpr.
+				 *
+				 * There is a fine point about PHVs that are supposed to be
+				 * evaluated at the RHS.  Such PHVs could only appear in the
+				 * semijoin's qual, since the rest of the query cannot
+				 * reference any outputs of the semijoin's RHS.  Therefore,
+				 * they can't actually go to null before being examined, and
+				 * it'd be OK to just remove the PHV wrapping.  We don't have
+				 * infrastructure for that, but remove_result_refs() will
+				 * relabel them as to be evaluated at the LHS, which is fine.
+				 */
+				if ((varno = get_result_relid(root, j->rarg)) != 0)
+				{
+					remove_result_refs(root, varno, j->larg);
+					if (j->quals)
+						jtnode = (Node *)
+							makeFromExpr(list_make1(j->larg), j->quals);
+					else
+						jtnode = j->larg;
+				}
+				break;
+			case JOIN_FULL:
+			case JOIN_ANTI:
+				/* We have no special smarts for these cases */
+				break;
+			default:
+				/* Note: JOIN_RIGHT should be gone at this point */
+				elog(ERROR, "unrecognized join type: %d",
+					 (int) j->jointype);
+				break;
+		}
+	}
+	else
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(jtnode));
+	return jtnode;
+}
+
+/*
+ * get_result_relid
+ *		If jtnode is a RangeTblRef for an RTE_RESULT RTE, return its relid;
+ *		otherwise return 0.
+ */
+static int
+get_result_relid(PlannerInfo *root, Node *jtnode)
+{
+	int			varno;
+
+	if (!IsA(jtnode, RangeTblRef))
+		return 0;
+	varno = ((RangeTblRef *) jtnode)->rtindex;
+	if (rt_fetch(varno, root->parse->rtable)->rtekind != RTE_RESULT)
+		return 0;
+	return varno;
+}
+
+/*
+ * remove_result_refs
+ *		Helper routine for dropping an unneeded RTE_RESULT RTE.
+ *
+ * This doesn't physically remove the RTE from the jointree, because that's
+ * more easily handled in remove_useless_results_recurse.  What it does do
+ * is the necessary cleanup in the rest of the tree: we must adjust any PHVs
+ * that may reference the RTE.  Be sure to call this at a point where the
+ * jointree is valid (no disconnected nodes).
+ *
+ * Note that we don't need to process the append_rel_list, since RTEs
+ * referenced directly in the jointree won't be appendrel members.
+ *
+ * varno is the RTE_RESULT's relid.
+ * newjtloc is the jointree location at which any PHVs referencing the
+ * RTE_RESULT should be evaluated instead.
+ */
+static void
+remove_result_refs(PlannerInfo *root, int varno, Node *newjtloc)
+{
+	/* Fix up PlaceHolderVars as needed */
+	/* If there are no PHVs anywhere, we can skip this bit */
+	if (root->glob->lastPHId != 0)
+	{
+		Relids		subrelids;
+
+		subrelids = get_relids_in_jointree(newjtloc, false);
+		Assert(!bms_is_empty(subrelids));
+		substitute_phv_relids((Node *) root->parse, varno, subrelids);
+		fix_append_rel_relids(root->append_rel_list, varno, subrelids);
+	}
+
+	/*
+	 * We also need to remove any PlanRowMark referencing the RTE, but we
+	 * postpone that work until we return to remove_useless_result_rtes.
+	 */
+}
+
+
+/*
+ * find_dependent_phvs - are there any PlaceHolderVars whose relids are
+ * exactly the given varno?
+ *
+ * find_dependent_phvs should be used when we want to see if there are
+ * any such PHVs anywhere in the Query.  Another use-case is to see if
+ * a subtree of the join tree contains such PHVs; but for that, we have
+ * to look not only at the join tree nodes themselves but at the
+ * referenced RTEs.  For that, use find_dependent_phvs_in_jointree.
+ */
+
+typedef struct
+{
+	Relids		relids;
+	int			sublevels_up;
+} find_dependent_phvs_context;
+
+static bool
+find_dependent_phvs_walker(Node *node,
+						   find_dependent_phvs_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		if (phv->phlevelsup == context->sublevels_up &&
+			bms_equal(context->relids, phv->phrels))
+			return true;
+		/* fall through to examine children */
+	}
+	if (IsA(node, Query))
+	{
+		/* Recurse into subselects */
+		bool		result;
+
+		context->sublevels_up++;
+		result = query_tree_walker((Query *) node,
+								   find_dependent_phvs_walker,
+								   (void *) context, 0);
+		context->sublevels_up--;
+		return result;
+	}
+	/* Shouldn't need to handle planner auxiliary nodes here */
+	Assert(!IsA(node, SpecialJoinInfo));
+	Assert(!IsA(node, AppendRelInfo));
+	Assert(!IsA(node, PlaceHolderInfo));
+	Assert(!IsA(node, MinMaxAggInfo));
+
+	return expression_tree_walker(node, find_dependent_phvs_walker,
+								  (void *) context);
+}
+
+static bool
+find_dependent_phvs(PlannerInfo *root, int varno)
+{
+	find_dependent_phvs_context context;
+
+	/* If there are no PHVs anywhere, we needn't work hard */
+	if (root->glob->lastPHId == 0)
+		return false;
+
+	context.relids = bms_make_singleton(varno);
+	context.sublevels_up = 0;
+
+	return query_tree_walker(root->parse,
+							 find_dependent_phvs_walker,
+							 (void *) &context,
+							 0);
+}
+
+static bool
+find_dependent_phvs_in_jointree(PlannerInfo *root, Node *node, int varno)
+{
+	find_dependent_phvs_context context;
+	Relids		subrelids;
+	int			relid;
+
+	/* If there are no PHVs anywhere, we needn't work hard */
+	if (root->glob->lastPHId == 0)
+		return false;
+
+	context.relids = bms_make_singleton(varno);
+	context.sublevels_up = 0;
+
+	/*
+	 * See if the jointree fragment itself contains references (in join quals)
+	 */
+	if (find_dependent_phvs_walker(node, &context))
+		return true;
+
+	/*
+	 * Otherwise, identify the set of referenced RTEs (we can ignore joins,
+	 * since they should be flattened already, so their join alias lists no
+	 * longer matter), and tediously check each RTE.  We can ignore RTEs that
+	 * are not marked LATERAL, though, since they couldn't possibly contain
+	 * any cross-references to other RTEs.
+	 */
+	subrelids = get_relids_in_jointree(node, false);
+	relid = -1;
+	while ((relid = bms_next_member(subrelids, relid)) >= 0)
+	{
+		RangeTblEntry *rte = rt_fetch(relid, root->parse->rtable);
+
+		if (rte->lateral &&
+			range_table_entry_walker(rte,
+									 find_dependent_phvs_walker,
+									 (void *) &context,
+									 0))
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * substitute_phv_relids - adjust PlaceHolderVar relid sets after pulling up
+ * a subquery or removing an RTE_RESULT jointree item
+ *
+ * Find any PlaceHolderVar nodes in the given tree that reference the
+ * pulled-up relid, and change them to reference the replacement relid(s).
+ *
+ * NOTE: although this has the form of a walker, we cheat and modify the
+ * nodes in-place.  This should be OK since the tree was copied by
+ * pullup_replace_vars earlier.  Avoid scribbling on the original values of
+ * the bitmapsets, though, because expression_tree_mutator doesn't copy those.
+ */
+
+typedef struct
+{
+	int			varno;
+	int			sublevels_up;
+	Relids		subrelids;
+} substitute_phv_relids_context;
+
+static bool
+substitute_phv_relids_walker(Node *node,
+							 substitute_phv_relids_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		if (phv->phlevelsup == context->sublevels_up &&
+			bms_is_member(context->varno, phv->phrels))
+		{
+			phv->phrels = bms_union(phv->phrels,
+									context->subrelids);
+			phv->phrels = bms_del_member(phv->phrels,
+										 context->varno);
+			/* Assert we haven't broken the PHV */
+			Assert(!bms_is_empty(phv->phrels));
+		}
+		/* fall through to examine children */
+	}
+	if (IsA(node, Query))
+	{
+		/* Recurse into subselects */
+		bool		result;
+
+		context->sublevels_up++;
+		result = query_tree_walker((Query *) node,
+								   substitute_phv_relids_walker,
+								   (void *) context, 0);
+		context->sublevels_up--;
+		return result;
+	}
+	/* Shouldn't need to handle planner auxiliary nodes here */
+	Assert(!IsA(node, SpecialJoinInfo));
+	Assert(!IsA(node, AppendRelInfo));
+	Assert(!IsA(node, PlaceHolderInfo));
+	Assert(!IsA(node, MinMaxAggInfo));
+
+	return expression_tree_walker(node, substitute_phv_relids_walker,
+								  (void *) context);
+}
+
+static void
+substitute_phv_relids(Node *node, int varno, Relids subrelids)
+{
+	substitute_phv_relids_context context;
+
+	context.varno = varno;
+	context.sublevels_up = 0;
+	context.subrelids = subrelids;
+
+	/*
+	 * Must be prepared to start with a Query or a bare expression tree.
+	 */
+	query_or_expression_tree_walker(node,
+									substitute_phv_relids_walker,
+									(void *) &context,
+									0);
+}
+
+/*
+ * fix_append_rel_relids: update RT-index fields of AppendRelInfo nodes
+ *
+ * When we pull up a subquery, any AppendRelInfo references to the subquery's
+ * RT index have to be replaced by the substituted relid (and there had better
+ * be only one).  We also need to apply substitute_phv_relids to their
+ * translated_vars lists, since those might contain PlaceHolderVars.
+ *
+ * We assume we may modify the AppendRelInfo nodes in-place.
+ */
+static void
+fix_append_rel_relids(List *append_rel_list, int varno, Relids subrelids)
+{
+	ListCell   *l;
+	int			subvarno = -1;
+
+	/*
+	 * We only want to extract the member relid once, but we mustn't fail
+	 * immediately if there are multiple members; it could be that none of the
+	 * AppendRelInfo nodes refer to it.  So compute it on first use. Note that
+	 * bms_singleton_member will complain if set is not singleton.
+	 */
+	foreach(l, append_rel_list)
+	{
+		AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
+
+		/* The parent_relid shouldn't ever be a pullup target */
+		Assert(appinfo->parent_relid != varno);
+
+		if (appinfo->child_relid == varno)
+		{
+			if (subvarno < 0)
+				subvarno = bms_singleton_member(subrelids);
+			appinfo->child_relid = subvarno;
+		}
+
+		/* Also fix up any PHVs in its translated vars */
+		substitute_phv_relids((Node *) appinfo->translated_vars,
+							  varno, subrelids);
+	}
+}
+
+/*
+ * get_relids_in_jointree: get set of RT indexes present in a jointree
+ *
+ * If include_joins is true, join RT indexes are included; if false,
+ * only base rels are included.
+ */
+Relids
+get_relids_in_jointree(Node *jtnode, bool include_joins)
+{
+	Relids		result = NULL;
+
+	if (jtnode == NULL)
+		return result;
+	if (IsA(jtnode, RangeTblRef))
+	{
+		int			varno = ((RangeTblRef *) jtnode)->rtindex;
+
+		result = bms_make_singleton(varno);
+	}
+	else if (IsA(jtnode, FromExpr))
+	{
+		FromExpr   *f = (FromExpr *) jtnode;
+		ListCell   *l;
+
+		foreach(l, f->fromlist)
+		{
+			result = bms_join(result,
+							  get_relids_in_jointree(lfirst(l),
+													 include_joins));
+		}
+	}
+	else if (IsA(jtnode, JoinExpr))
+	{
+		JoinExpr   *j = (JoinExpr *) jtnode;
+
+		result = get_relids_in_jointree(j->larg, include_joins);
+		result = bms_join(result,
+						  get_relids_in_jointree(j->rarg, include_joins));
+		if (include_joins && j->rtindex)
+			result = bms_add_member(result, j->rtindex);
+	}
+	else
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(jtnode));
+	return result;
+}
+
+/*
+ * get_relids_for_join: get set of base RT indexes making up a join
+ */
+Relids
+get_relids_for_join(Query *query, int joinrelid)
+{
+	Node	   *jtnode;
+
+	jtnode = find_jointree_node_for_rel((Node *) query->jointree,
+										joinrelid);
+	if (!jtnode)
+		elog(ERROR, "could not find join node %d", joinrelid);
+	return get_relids_in_jointree(jtnode, false);
+}
+
+/*
+ * find_jointree_node_for_rel: locate jointree node for a base or join RT index
+ *
+ * Returns NULL if not found
+ */
+static Node *
+find_jointree_node_for_rel(Node *jtnode, int relid)
+{
+	if (jtnode == NULL)
+		return NULL;
+	if (IsA(jtnode, RangeTblRef))
+	{
+		int			varno = ((RangeTblRef *) jtnode)->rtindex;
+
+		if (relid == varno)
+			return jtnode;
+	}
+	else if (IsA(jtnode, FromExpr))
+	{
+		FromExpr   *f = (FromExpr *) jtnode;
+		ListCell   *l;
+
+		foreach(l, f->fromlist)
+		{
+			jtnode = find_jointree_node_for_rel(lfirst(l), relid);
+			if (jtnode)
+				return jtnode;
+		}
+	}
+	else if (IsA(jtnode, JoinExpr))
+	{
+		JoinExpr   *j = (JoinExpr *) jtnode;
+
+		if (relid == j->rtindex)
+			return jtnode;
+		jtnode = find_jointree_node_for_rel(j->larg, relid);
+		if (jtnode)
+			return jtnode;
+		jtnode = find_jointree_node_for_rel(j->rarg, relid);
+		if (jtnode)
+			return jtnode;
+	}
+	else
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(jtnode));
+	return NULL;
+}