Adding upstream version 15.5.upstream/15.5

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

1 files changed, 3696 insertions, 0 deletions

diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c
new file mode 100644
index 0000000..d821969
--- /dev/null
+++ b/src/backend/parser/parse_clause.c
@@ -0,0 +1,3696 @@
+/*-------------------------------------------------------------------------
+ *
+ * parse_clause.c
+ *	  handle clauses in parser
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/parser/parse_clause.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "access/nbtree.h"
+#include "access/table.h"
+#include "access/tsmapi.h"
+#include "catalog/catalog.h"
+#include "catalog/heap.h"
+#include "catalog/pg_am.h"
+#include "catalog/pg_amproc.h"
+#include "catalog/pg_collation.h"
+#include "catalog/pg_constraint.h"
+#include "catalog/pg_type.h"
+#include "commands/defrem.h"
+#include "miscadmin.h"
+#include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
+#include "optimizer/optimizer.h"
+#include "parser/analyze.h"
+#include "parser/parse_clause.h"
+#include "parser/parse_coerce.h"
+#include "parser/parse_collate.h"
+#include "parser/parse_expr.h"
+#include "parser/parse_func.h"
+#include "parser/parse_oper.h"
+#include "parser/parse_relation.h"
+#include "parser/parse_target.h"
+#include "parser/parse_type.h"
+#include "parser/parser.h"
+#include "parser/parsetree.h"
+#include "rewrite/rewriteManip.h"
+#include "utils/builtins.h"
+#include "utils/catcache.h"
+#include "utils/guc.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/syscache.h"
+
+
+static int	extractRemainingColumns(ParseNamespaceColumn *src_nscolumns,
+									List *src_colnames,
+									List **src_colnos,
+									List **res_colnames, List **res_colvars,
+									ParseNamespaceColumn *res_nscolumns);
+static Node *transformJoinUsingClause(ParseState *pstate,
+									  List *leftVars, List *rightVars);
+static Node *transformJoinOnClause(ParseState *pstate, JoinExpr *j,
+								   List *namespace);
+static ParseNamespaceItem *transformTableEntry(ParseState *pstate, RangeVar *r);
+static ParseNamespaceItem *transformRangeSubselect(ParseState *pstate,
+												   RangeSubselect *r);
+static ParseNamespaceItem *transformRangeFunction(ParseState *pstate,
+												  RangeFunction *r);
+static ParseNamespaceItem *transformRangeTableFunc(ParseState *pstate,
+												   RangeTableFunc *t);
+static TableSampleClause *transformRangeTableSample(ParseState *pstate,
+													RangeTableSample *rts);
+static ParseNamespaceItem *getNSItemForSpecialRelationTypes(ParseState *pstate,
+															RangeVar *rv);
+static Node *transformFromClauseItem(ParseState *pstate, Node *n,
+									 ParseNamespaceItem **top_nsitem,
+									 List **namespace);
+static Var *buildVarFromNSColumn(ParseNamespaceColumn *nscol);
+static Node *buildMergedJoinVar(ParseState *pstate, JoinType jointype,
+								Var *l_colvar, Var *r_colvar);
+static void setNamespaceColumnVisibility(List *namespace, bool cols_visible);
+static void setNamespaceLateralState(List *namespace,
+									 bool lateral_only, bool lateral_ok);
+static void checkExprIsVarFree(ParseState *pstate, Node *n,
+							   const char *constructName);
+static TargetEntry *findTargetlistEntrySQL92(ParseState *pstate, Node *node,
+											 List **tlist, ParseExprKind exprKind);
+static TargetEntry *findTargetlistEntrySQL99(ParseState *pstate, Node *node,
+											 List **tlist, ParseExprKind exprKind);
+static int	get_matching_location(int sortgroupref,
+								  List *sortgrouprefs, List *exprs);
+static List *resolve_unique_index_expr(ParseState *pstate, InferClause *infer,
+									   Relation heapRel);
+static List *addTargetToGroupList(ParseState *pstate, TargetEntry *tle,
+								  List *grouplist, List *targetlist, int location);
+static WindowClause *findWindowClause(List *wclist, const char *name);
+static Node *transformFrameOffset(ParseState *pstate, int frameOptions,
+								  Oid rangeopfamily, Oid rangeopcintype, Oid *inRangeFunc,
+								  Node *clause);
+
+
+/*
+ * transformFromClause -
+ *	  Process the FROM clause and add items to the query's range table,
+ *	  joinlist, and namespace.
+ *
+ * Note: we assume that the pstate's p_rtable, p_joinlist, and p_namespace
+ * lists were initialized to NIL when the pstate was created.
+ * We will add onto any entries already present --- this is needed for rule
+ * processing, as well as for UPDATE and DELETE.
+ */
+void
+transformFromClause(ParseState *pstate, List *frmList)
+{
+	ListCell   *fl;
+
+	/*
+	 * The grammar will have produced a list of RangeVars, RangeSubselects,
+	 * RangeFunctions, and/or JoinExprs. Transform each one (possibly adding
+	 * entries to the rtable), check for duplicate refnames, and then add it
+	 * to the joinlist and namespace.
+	 *
+	 * Note we must process the items left-to-right for proper handling of
+	 * LATERAL references.
+	 */
+	foreach(fl, frmList)
+	{
+		Node	   *n = lfirst(fl);
+		ParseNamespaceItem *nsitem;
+		List	   *namespace;
+
+		n = transformFromClauseItem(pstate, n,
+									&nsitem,
+									&namespace);
+
+		checkNameSpaceConflicts(pstate, pstate->p_namespace, namespace);
+
+		/* Mark the new namespace items as visible only to LATERAL */
+		setNamespaceLateralState(namespace, true, true);
+
+		pstate->p_joinlist = lappend(pstate->p_joinlist, n);
+		pstate->p_namespace = list_concat(pstate->p_namespace, namespace);
+	}
+
+	/*
+	 * We're done parsing the FROM list, so make all namespace items
+	 * unconditionally visible.  Note that this will also reset lateral_only
+	 * for any namespace items that were already present when we were called;
+	 * but those should have been that way already.
+	 */
+	setNamespaceLateralState(pstate->p_namespace, false, true);
+}
+
+/*
+ * setTargetTable
+ *	  Add the target relation of INSERT/UPDATE/DELETE/MERGE to the range table,
+ *	  and make the special links to it in the ParseState.
+ *
+ *	  We also open the target relation and acquire a write lock on it.
+ *	  This must be done before processing the FROM list, in case the target
+ *	  is also mentioned as a source relation --- we want to be sure to grab
+ *	  the write lock before any read lock.
+ *
+ *	  If alsoSource is true, add the target to the query's joinlist and
+ *	  namespace.  For INSERT, we don't want the target to be joined to;
+ *	  it's a destination of tuples, not a source.  MERGE is actually
+ *	  both, but we'll add it separately to joinlist and namespace, so
+ *	  doing nothing (like INSERT) is correct here.  For UPDATE/DELETE,
+ *	  we do need to scan or join the target.  (NOTE: we do not bother
+ *	  to check for namespace conflict; we assume that the namespace was
+ *	  initially empty in these cases.)
+ *
+ *	  Finally, we mark the relation as requiring the permissions specified
+ *	  by requiredPerms.
+ *
+ *	  Returns the rangetable index of the target relation.
+ */
+int
+setTargetTable(ParseState *pstate, RangeVar *relation,
+			   bool inh, bool alsoSource, AclMode requiredPerms)
+{
+	ParseNamespaceItem *nsitem;
+
+	/*
+	 * ENRs hide tables of the same name, so we need to check for them first.
+	 * In contrast, CTEs don't hide tables (for this purpose).
+	 */
+	if (relation->schemaname == NULL &&
+		scanNameSpaceForENR(pstate, relation->relname))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("relation \"%s\" cannot be the target of a modifying statement",
+						relation->relname)));
+
+	/* Close old target; this could only happen for multi-action rules */
+	if (pstate->p_target_relation != NULL)
+		table_close(pstate->p_target_relation, NoLock);
+
+	/*
+	 * Open target rel and grab suitable lock (which we will hold till end of
+	 * transaction).
+	 *
+	 * free_parsestate() will eventually do the corresponding table_close(),
+	 * but *not* release the lock.
+	 */
+	pstate->p_target_relation = parserOpenTable(pstate, relation,
+												RowExclusiveLock);
+
+	/*
+	 * Now build an RTE and a ParseNamespaceItem.
+	 */
+	nsitem = addRangeTableEntryForRelation(pstate, pstate->p_target_relation,
+										   RowExclusiveLock,
+										   relation->alias, inh, false);
+
+	/* remember the RTE/nsitem as being the query target */
+	pstate->p_target_nsitem = nsitem;
+
+	/*
+	 * Override addRangeTableEntry's default ACL_SELECT permissions check, and
+	 * instead mark target table as requiring exactly the specified
+	 * permissions.
+	 *
+	 * If we find an explicit reference to the rel later during parse
+	 * analysis, we will add the ACL_SELECT bit back again; see
+	 * markVarForSelectPriv and its callers.
+	 */
+	nsitem->p_rte->requiredPerms = requiredPerms;
+
+	/*
+	 * If UPDATE/DELETE, add table to joinlist and namespace.
+	 */
+	if (alsoSource)
+		addNSItemToQuery(pstate, nsitem, true, true, true);
+
+	return nsitem->p_rtindex;
+}
+
+/*
+ * Extract all not-in-common columns from column lists of a source table
+ *
+ * src_nscolumns and src_colnames describe the source table.
+ *
+ * *src_colnos initially contains the column numbers of the already-merged
+ * columns.  We add to it the column number of each additional column.
+ * Also append to *res_colnames the name of each additional column,
+ * append to *res_colvars a Var for each additional column, and copy the
+ * columns' nscolumns data into res_nscolumns[] (which is caller-allocated
+ * space that had better be big enough).
+ *
+ * Returns the number of columns added.
+ */
+static int
+extractRemainingColumns(ParseNamespaceColumn *src_nscolumns,
+						List *src_colnames,
+						List **src_colnos,
+						List **res_colnames, List **res_colvars,
+						ParseNamespaceColumn *res_nscolumns)
+{
+	int			colcount = 0;
+	Bitmapset  *prevcols;
+	int			attnum;
+	ListCell   *lc;
+
+	/*
+	 * While we could just test "list_member_int(*src_colnos, attnum)" to
+	 * detect already-merged columns in the loop below, that would be O(N^2)
+	 * for a wide input table.  Instead build a bitmapset of just the merged
+	 * USING columns, which we won't add to within the main loop.
+	 */
+	prevcols = NULL;
+	foreach(lc, *src_colnos)
+	{
+		prevcols = bms_add_member(prevcols, lfirst_int(lc));
+	}
+
+	attnum = 0;
+	foreach(lc, src_colnames)
+	{
+		char	   *colname = strVal(lfirst(lc));
+
+		attnum++;
+		/* Non-dropped and not already merged? */
+		if (colname[0] != '\0' && !bms_is_member(attnum, prevcols))
+		{
+			/* Yes, so emit it as next output column */
+			*src_colnos = lappend_int(*src_colnos, attnum);
+			*res_colnames = lappend(*res_colnames, lfirst(lc));
+			*res_colvars = lappend(*res_colvars,
+								   buildVarFromNSColumn(src_nscolumns + attnum - 1));
+			/* Copy the input relation's nscolumn data for this column */
+			res_nscolumns[colcount] = src_nscolumns[attnum - 1];
+			colcount++;
+		}
+	}
+	return colcount;
+}
+
+/* transformJoinUsingClause()
+ *	  Build a complete ON clause from a partially-transformed USING list.
+ *	  We are given lists of nodes representing left and right match columns.
+ *	  Result is a transformed qualification expression.
+ */
+static Node *
+transformJoinUsingClause(ParseState *pstate,
+						 List *leftVars, List *rightVars)
+{
+	Node	   *result;
+	List	   *andargs = NIL;
+	ListCell   *lvars,
+			   *rvars;
+
+	/*
+	 * We cheat a little bit here by building an untransformed operator tree
+	 * whose leaves are the already-transformed Vars.  This requires collusion
+	 * from transformExpr(), which normally could be expected to complain
+	 * about already-transformed subnodes.  However, this does mean that we
+	 * have to mark the columns as requiring SELECT privilege for ourselves;
+	 * transformExpr() won't do it.
+	 */
+	forboth(lvars, leftVars, rvars, rightVars)
+	{
+		Var		   *lvar = (Var *) lfirst(lvars);
+		Var		   *rvar = (Var *) lfirst(rvars);
+		A_Expr	   *e;
+
+		/* Require read access to the join variables */
+		markVarForSelectPriv(pstate, lvar);
+		markVarForSelectPriv(pstate, rvar);
+
+		/* Now create the lvar = rvar join condition */
+		e = makeSimpleA_Expr(AEXPR_OP, "=",
+							 (Node *) copyObject(lvar), (Node *) copyObject(rvar),
+							 -1);
+
+		/* Prepare to combine into an AND clause, if multiple join columns */
+		andargs = lappend(andargs, e);
+	}
+
+	/* Only need an AND if there's more than one join column */
+	if (list_length(andargs) == 1)
+		result = (Node *) linitial(andargs);
+	else
+		result = (Node *) makeBoolExpr(AND_EXPR, andargs, -1);
+
+	/*
+	 * Since the references are already Vars, and are certainly from the input
+	 * relations, we don't have to go through the same pushups that
+	 * transformJoinOnClause() does.  Just invoke transformExpr() to fix up
+	 * the operators, and we're done.
+	 */
+	result = transformExpr(pstate, result, EXPR_KIND_JOIN_USING);
+
+	result = coerce_to_boolean(pstate, result, "JOIN/USING");
+
+	return result;
+}
+
+/* transformJoinOnClause()
+ *	  Transform the qual conditions for JOIN/ON.
+ *	  Result is a transformed qualification expression.
+ */
+static Node *
+transformJoinOnClause(ParseState *pstate, JoinExpr *j, List *namespace)
+{
+	Node	   *result;
+	List	   *save_namespace;
+
+	/*
+	 * The namespace that the join expression should see is just the two
+	 * subtrees of the JOIN plus any outer references from upper pstate
+	 * levels.  Temporarily set this pstate's namespace accordingly.  (We need
+	 * not check for refname conflicts, because transformFromClauseItem()
+	 * already did.)  All namespace items are marked visible regardless of
+	 * LATERAL state.
+	 */
+	setNamespaceLateralState(namespace, false, true);
+
+	save_namespace = pstate->p_namespace;
+	pstate->p_namespace = namespace;
+
+	result = transformWhereClause(pstate, j->quals,
+								  EXPR_KIND_JOIN_ON, "JOIN/ON");
+
+	pstate->p_namespace = save_namespace;
+
+	return result;
+}
+
+/*
+ * transformTableEntry --- transform a RangeVar (simple relation reference)
+ */
+static ParseNamespaceItem *
+transformTableEntry(ParseState *pstate, RangeVar *r)
+{
+	/* addRangeTableEntry does all the work */
+	return addRangeTableEntry(pstate, r, r->alias, r->inh, true);
+}
+
+/*
+ * transformRangeSubselect --- transform a sub-SELECT appearing in FROM
+ */
+static ParseNamespaceItem *
+transformRangeSubselect(ParseState *pstate, RangeSubselect *r)
+{
+	Query	   *query;
+
+	/*
+	 * We require user to supply an alias for a subselect, per SQL92. To relax
+	 * this, we'd have to be prepared to gin up a unique alias for an
+	 * unlabeled subselect.  (This is just elog, not ereport, because the
+	 * grammar should have enforced it already.  It'd probably be better to
+	 * report the error here, but we don't have a good error location here.)
+	 */
+	if (r->alias == NULL)
+		elog(ERROR, "subquery in FROM must have an alias");
+
+	/*
+	 * Set p_expr_kind to show this parse level is recursing to a subselect.
+	 * We can't be nested within any expression, so don't need save-restore
+	 * logic here.
+	 */
+	Assert(pstate->p_expr_kind == EXPR_KIND_NONE);
+	pstate->p_expr_kind = EXPR_KIND_FROM_SUBSELECT;
+
+	/*
+	 * If the subselect is LATERAL, make lateral_only names of this level
+	 * visible to it.  (LATERAL can't nest within a single pstate level, so we
+	 * don't need save/restore logic here.)
+	 */
+	Assert(!pstate->p_lateral_active);
+	pstate->p_lateral_active = r->lateral;
+
+	/*
+	 * Analyze and transform the subquery.
+	 */
+	query = parse_sub_analyze(r->subquery, pstate, NULL,
+							  isLockedRefname(pstate, r->alias->aliasname),
+							  true);
+
+	/* Restore state */
+	pstate->p_lateral_active = false;
+	pstate->p_expr_kind = EXPR_KIND_NONE;
+
+	/*
+	 * Check that we got a SELECT.  Anything else should be impossible given
+	 * restrictions of the grammar, but check anyway.
+	 */
+	if (!IsA(query, Query) ||
+		query->commandType != CMD_SELECT)
+		elog(ERROR, "unexpected non-SELECT command in subquery in FROM");
+
+	/*
+	 * OK, build an RTE and nsitem for the subquery.
+	 */
+	return addRangeTableEntryForSubquery(pstate,
+										 query,
+										 r->alias,
+										 r->lateral,
+										 true);
+}
+
+
+/*
+ * transformRangeFunction --- transform a function call appearing in FROM
+ */
+static ParseNamespaceItem *
+transformRangeFunction(ParseState *pstate, RangeFunction *r)
+{
+	List	   *funcexprs = NIL;
+	List	   *funcnames = NIL;
+	List	   *coldeflists = NIL;
+	bool		is_lateral;
+	ListCell   *lc;
+
+	/*
+	 * We make lateral_only names of this level visible, whether or not the
+	 * RangeFunction is explicitly marked LATERAL.  This is needed for SQL
+	 * spec compliance in the case of UNNEST(), and seems useful on
+	 * convenience grounds for all functions in FROM.
+	 *
+	 * (LATERAL can't nest within a single pstate level, so we don't need
+	 * save/restore logic here.)
+	 */
+	Assert(!pstate->p_lateral_active);
+	pstate->p_lateral_active = true;
+
+	/*
+	 * Transform the raw expressions.
+	 *
+	 * While transforming, also save function names for possible use as alias
+	 * and column names.  We use the same transformation rules as for a SELECT
+	 * output expression.  For a FuncCall node, the result will be the
+	 * function name, but it is possible for the grammar to hand back other
+	 * node types.
+	 *
+	 * We have to get this info now, because FigureColname only works on raw
+	 * parsetrees.  Actually deciding what to do with the names is left up to
+	 * addRangeTableEntryForFunction.
+	 *
+	 * Likewise, collect column definition lists if there were any.  But
+	 * complain if we find one here and the RangeFunction has one too.
+	 */
+	foreach(lc, r->functions)
+	{
+		List	   *pair = (List *) lfirst(lc);
+		Node	   *fexpr;
+		List	   *coldeflist;
+		Node	   *newfexpr;
+		Node	   *last_srf;
+
+		/* Disassemble the function-call/column-def-list pairs */
+		Assert(list_length(pair) == 2);
+		fexpr = (Node *) linitial(pair);
+		coldeflist = (List *) lsecond(pair);
+
+		/*
+		 * If we find a function call unnest() with more than one argument and
+		 * no special decoration, transform it into separate unnest() calls on
+		 * each argument.  This is a kluge, for sure, but it's less nasty than
+		 * other ways of implementing the SQL-standard UNNEST() syntax.
+		 *
+		 * If there is any decoration (including a coldeflist), we don't
+		 * transform, which probably means a no-such-function error later.  We
+		 * could alternatively throw an error right now, but that doesn't seem
+		 * tremendously helpful.  If someone is using any such decoration,
+		 * then they're not using the SQL-standard syntax, and they're more
+		 * likely expecting an un-tweaked function call.
+		 *
+		 * Note: the transformation changes a non-schema-qualified unnest()
+		 * function name into schema-qualified pg_catalog.unnest().  This
+		 * choice is also a bit debatable, but it seems reasonable to force
+		 * use of built-in unnest() when we make this transformation.
+		 */
+		if (IsA(fexpr, FuncCall))
+		{
+			FuncCall   *fc = (FuncCall *) fexpr;
+
+			if (list_length(fc->funcname) == 1 &&
+				strcmp(strVal(linitial(fc->funcname)), "unnest") == 0 &&
+				list_length(fc->args) > 1 &&
+				fc->agg_order == NIL &&
+				fc->agg_filter == NULL &&
+				fc->over == NULL &&
+				!fc->agg_star &&
+				!fc->agg_distinct &&
+				!fc->func_variadic &&
+				coldeflist == NIL)
+			{
+				ListCell   *lc;
+
+				foreach(lc, fc->args)
+				{
+					Node	   *arg = (Node *) lfirst(lc);
+					FuncCall   *newfc;
+
+					last_srf = pstate->p_last_srf;
+
+					newfc = makeFuncCall(SystemFuncName("unnest"),
+										 list_make1(arg),
+										 COERCE_EXPLICIT_CALL,
+										 fc->location);
+
+					newfexpr = transformExpr(pstate, (Node *) newfc,
+											 EXPR_KIND_FROM_FUNCTION);
+
+					/* nodeFunctionscan.c requires SRFs to be at top level */
+					if (pstate->p_last_srf != last_srf &&
+						pstate->p_last_srf != newfexpr)
+						ereport(ERROR,
+								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+								 errmsg("set-returning functions must appear at top level of FROM"),
+								 parser_errposition(pstate,
+													exprLocation(pstate->p_last_srf))));
+
+					funcexprs = lappend(funcexprs, newfexpr);
+
+					funcnames = lappend(funcnames,
+										FigureColname((Node *) newfc));
+
+					/* coldeflist is empty, so no error is possible */
+
+					coldeflists = lappend(coldeflists, coldeflist);
+				}
+				continue;		/* done with this function item */
+			}
+		}
+
+		/* normal case ... */
+		last_srf = pstate->p_last_srf;
+
+		newfexpr = transformExpr(pstate, fexpr,
+								 EXPR_KIND_FROM_FUNCTION);
+
+		/* nodeFunctionscan.c requires SRFs to be at top level */
+		if (pstate->p_last_srf != last_srf &&
+			pstate->p_last_srf != newfexpr)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("set-returning functions must appear at top level of FROM"),
+					 parser_errposition(pstate,
+										exprLocation(pstate->p_last_srf))));
+
+		funcexprs = lappend(funcexprs, newfexpr);
+
+		funcnames = lappend(funcnames,
+							FigureColname(fexpr));
+
+		if (coldeflist && r->coldeflist)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("multiple column definition lists are not allowed for the same function"),
+					 parser_errposition(pstate,
+										exprLocation((Node *) r->coldeflist))));
+
+		coldeflists = lappend(coldeflists, coldeflist);
+	}
+
+	pstate->p_lateral_active = false;
+
+	/*
+	 * We must assign collations now so that the RTE exposes correct collation
+	 * info for Vars created from it.
+	 */
+	assign_list_collations(pstate, funcexprs);
+
+	/*
+	 * Install the top-level coldeflist if there was one (we already checked
+	 * that there was no conflicting per-function coldeflist).
+	 *
+	 * We only allow this when there's a single function (even after UNNEST
+	 * expansion) and no WITH ORDINALITY.  The reason for the latter
+	 * restriction is that it's not real clear whether the ordinality column
+	 * should be in the coldeflist, and users are too likely to make mistakes
+	 * in one direction or the other.  Putting the coldeflist inside ROWS
+	 * FROM() is much clearer in this case.
+	 */
+	if (r->coldeflist)
+	{
+		if (list_length(funcexprs) != 1)
+		{
+			if (r->is_rowsfrom)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("ROWS FROM() with multiple functions cannot have a column definition list"),
+						 errhint("Put a separate column definition list for each function inside ROWS FROM()."),
+						 parser_errposition(pstate,
+											exprLocation((Node *) r->coldeflist))));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("UNNEST() with multiple arguments cannot have a column definition list"),
+						 errhint("Use separate UNNEST() calls inside ROWS FROM(), and attach a column definition list to each one."),
+						 parser_errposition(pstate,
+											exprLocation((Node *) r->coldeflist))));
+		}
+		if (r->ordinality)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("WITH ORDINALITY cannot be used with a column definition list"),
+					 errhint("Put the column definition list inside ROWS FROM()."),
+					 parser_errposition(pstate,
+										exprLocation((Node *) r->coldeflist))));
+
+		coldeflists = list_make1(r->coldeflist);
+	}
+
+	/*
+	 * Mark the RTE as LATERAL if the user said LATERAL explicitly, or if
+	 * there are any lateral cross-references in it.
+	 */
+	is_lateral = r->lateral || contain_vars_of_level((Node *) funcexprs, 0);
+
+	/*
+	 * OK, build an RTE and nsitem for the function.
+	 */
+	return addRangeTableEntryForFunction(pstate,
+										 funcnames, funcexprs, coldeflists,
+										 r, is_lateral, true);
+}
+
+/*
+ * transformRangeTableFunc -
+ *			Transform a raw RangeTableFunc into TableFunc.
+ *
+ * Transform the namespace clauses, the document-generating expression, the
+ * row-generating expression, the column-generating expressions, and the
+ * default value expressions.
+ */
+static ParseNamespaceItem *
+transformRangeTableFunc(ParseState *pstate, RangeTableFunc *rtf)
+{
+	TableFunc  *tf = makeNode(TableFunc);
+	const char *constructName;
+	Oid			docType;
+	bool		is_lateral;
+	ListCell   *col;
+	char	  **names;
+	int			colno;
+
+	/* Currently only XMLTABLE is supported */
+	constructName = "XMLTABLE";
+	docType = XMLOID;
+
+	/*
+	 * We make lateral_only names of this level visible, whether or not the
+	 * RangeTableFunc is explicitly marked LATERAL.  This is needed for SQL
+	 * spec compliance and seems useful on convenience grounds for all
+	 * functions in FROM.
+	 *
+	 * (LATERAL can't nest within a single pstate level, so we don't need
+	 * save/restore logic here.)
+	 */
+	Assert(!pstate->p_lateral_active);
+	pstate->p_lateral_active = true;
+
+	/* Transform and apply typecast to the row-generating expression ... */
+	Assert(rtf->rowexpr != NULL);
+	tf->rowexpr = coerce_to_specific_type(pstate,
+										  transformExpr(pstate, rtf->rowexpr, EXPR_KIND_FROM_FUNCTION),
+										  TEXTOID,
+										  constructName);
+	assign_expr_collations(pstate, tf->rowexpr);
+
+	/* ... and to the document itself */
+	Assert(rtf->docexpr != NULL);
+	tf->docexpr = coerce_to_specific_type(pstate,
+										  transformExpr(pstate, rtf->docexpr, EXPR_KIND_FROM_FUNCTION),
+										  docType,
+										  constructName);
+	assign_expr_collations(pstate, tf->docexpr);
+
+	/* undef ordinality column number */
+	tf->ordinalitycol = -1;
+
+	/* Process column specs */
+	names = palloc(sizeof(char *) * list_length(rtf->columns));
+
+	colno = 0;
+	foreach(col, rtf->columns)
+	{
+		RangeTableFuncCol *rawc = (RangeTableFuncCol *) lfirst(col);
+		Oid			typid;
+		int32		typmod;
+		Node	   *colexpr;
+		Node	   *coldefexpr;
+		int			j;
+
+		tf->colnames = lappend(tf->colnames,
+							   makeString(pstrdup(rawc->colname)));
+
+		/*
+		 * Determine the type and typmod for the new column. FOR ORDINALITY
+		 * columns are INTEGER per spec; the others are user-specified.
+		 */
+		if (rawc->for_ordinality)
+		{
+			if (tf->ordinalitycol != -1)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("only one FOR ORDINALITY column is allowed"),
+						 parser_errposition(pstate, rawc->location)));
+
+			typid = INT4OID;
+			typmod = -1;
+			tf->ordinalitycol = colno;
+		}
+		else
+		{
+			if (rawc->typeName->setof)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("column \"%s\" cannot be declared SETOF",
+								rawc->colname),
+						 parser_errposition(pstate, rawc->location)));
+
+			typenameTypeIdAndMod(pstate, rawc->typeName,
+								 &typid, &typmod);
+		}
+
+		tf->coltypes = lappend_oid(tf->coltypes, typid);
+		tf->coltypmods = lappend_int(tf->coltypmods, typmod);
+		tf->colcollations = lappend_oid(tf->colcollations,
+										get_typcollation(typid));
+
+		/* Transform the PATH and DEFAULT expressions */
+		if (rawc->colexpr)
+		{
+			colexpr = coerce_to_specific_type(pstate,
+											  transformExpr(pstate, rawc->colexpr,
+															EXPR_KIND_FROM_FUNCTION),
+											  TEXTOID,
+											  constructName);
+			assign_expr_collations(pstate, colexpr);
+		}
+		else
+			colexpr = NULL;
+
+		if (rawc->coldefexpr)
+		{
+			coldefexpr = coerce_to_specific_type_typmod(pstate,
+														transformExpr(pstate, rawc->coldefexpr,
+																	  EXPR_KIND_FROM_FUNCTION),
+														typid, typmod,
+														constructName);
+			assign_expr_collations(pstate, coldefexpr);
+		}
+		else
+			coldefexpr = NULL;
+
+		tf->colexprs = lappend(tf->colexprs, colexpr);
+		tf->coldefexprs = lappend(tf->coldefexprs, coldefexpr);
+
+		if (rawc->is_not_null)
+			tf->notnulls = bms_add_member(tf->notnulls, colno);
+
+		/* make sure column names are unique */
+		for (j = 0; j < colno; j++)
+			if (strcmp(names[j], rawc->colname) == 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("column name \"%s\" is not unique",
+								rawc->colname),
+						 parser_errposition(pstate, rawc->location)));
+		names[colno] = rawc->colname;
+
+		colno++;
+	}
+	pfree(names);
+
+	/* Namespaces, if any, also need to be transformed */
+	if (rtf->namespaces != NIL)
+	{
+		ListCell   *ns;
+		ListCell   *lc2;
+		List	   *ns_uris = NIL;
+		List	   *ns_names = NIL;
+		bool		default_ns_seen = false;
+
+		foreach(ns, rtf->namespaces)
+		{
+			ResTarget  *r = (ResTarget *) lfirst(ns);
+			Node	   *ns_uri;
+
+			Assert(IsA(r, ResTarget));
+			ns_uri = transformExpr(pstate, r->val, EXPR_KIND_FROM_FUNCTION);
+			ns_uri = coerce_to_specific_type(pstate, ns_uri,
+											 TEXTOID, constructName);
+			assign_expr_collations(pstate, ns_uri);
+			ns_uris = lappend(ns_uris, ns_uri);
+
+			/* Verify consistency of name list: no dupes, only one DEFAULT */
+			if (r->name != NULL)
+			{
+				foreach(lc2, ns_names)
+				{
+					String	   *ns_node = lfirst_node(String, lc2);
+
+					if (ns_node == NULL)
+						continue;
+					if (strcmp(strVal(ns_node), r->name) == 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_SYNTAX_ERROR),
+								 errmsg("namespace name \"%s\" is not unique",
+										r->name),
+								 parser_errposition(pstate, r->location)));
+				}
+			}
+			else
+			{
+				if (default_ns_seen)
+					ereport(ERROR,
+							(errcode(ERRCODE_SYNTAX_ERROR),
+							 errmsg("only one default namespace is allowed"),
+							 parser_errposition(pstate, r->location)));
+				default_ns_seen = true;
+			}
+
+			/* We represent DEFAULT by a null pointer */
+			ns_names = lappend(ns_names,
+							   r->name ? makeString(r->name) : NULL);
+		}
+
+		tf->ns_uris = ns_uris;
+		tf->ns_names = ns_names;
+	}
+
+	tf->location = rtf->location;
+
+	pstate->p_lateral_active = false;
+
+	/*
+	 * Mark the RTE as LATERAL if the user said LATERAL explicitly, or if
+	 * there are any lateral cross-references in it.
+	 */
+	is_lateral = rtf->lateral || contain_vars_of_level((Node *) tf, 0);
+
+	return addRangeTableEntryForTableFunc(pstate,
+										  tf, rtf->alias, is_lateral, true);
+}
+
+/*
+ * transformRangeTableSample --- transform a TABLESAMPLE clause
+ *
+ * Caller has already transformed rts->relation, we just have to validate
+ * the remaining fields and create a TableSampleClause node.
+ */
+static TableSampleClause *
+transformRangeTableSample(ParseState *pstate, RangeTableSample *rts)
+{
+	TableSampleClause *tablesample;
+	Oid			handlerOid;
+	Oid			funcargtypes[1];
+	TsmRoutine *tsm;
+	List	   *fargs;
+	ListCell   *larg,
+			   *ltyp;
+
+	/*
+	 * To validate the sample method name, look up the handler function, which
+	 * has the same name, one dummy INTERNAL argument, and a result type of
+	 * tsm_handler.  (Note: tablesample method names are not schema-qualified
+	 * in the SQL standard; but since they are just functions to us, we allow
+	 * schema qualification to resolve any potential ambiguity.)
+	 */
+	funcargtypes[0] = INTERNALOID;
+
+	handlerOid = LookupFuncName(rts->method, 1, funcargtypes, true);
+
+	/* we want error to complain about no-such-method, not no-such-function */
+	if (!OidIsValid(handlerOid))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("tablesample method %s does not exist",
+						NameListToString(rts->method)),
+				 parser_errposition(pstate, rts->location)));
+
+	/* check that handler has correct return type */
+	if (get_func_rettype(handlerOid) != TSM_HANDLEROID)
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("function %s must return type %s",
+						NameListToString(rts->method), "tsm_handler"),
+				 parser_errposition(pstate, rts->location)));
+
+	/* OK, run the handler to get TsmRoutine, for argument type info */
+	tsm = GetTsmRoutine(handlerOid);
+
+	tablesample = makeNode(TableSampleClause);
+	tablesample->tsmhandler = handlerOid;
+
+	/* check user provided the expected number of arguments */
+	if (list_length(rts->args) != list_length(tsm->parameterTypes))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TABLESAMPLE_ARGUMENT),
+				 errmsg_plural("tablesample method %s requires %d argument, not %d",
+							   "tablesample method %s requires %d arguments, not %d",
+							   list_length(tsm->parameterTypes),
+							   NameListToString(rts->method),
+							   list_length(tsm->parameterTypes),
+							   list_length(rts->args)),
+				 parser_errposition(pstate, rts->location)));
+
+	/*
+	 * Transform the arguments, typecasting them as needed.  Note we must also
+	 * assign collations now, because assign_query_collations() doesn't
+	 * examine any substructure of RTEs.
+	 */
+	fargs = NIL;
+	forboth(larg, rts->args, ltyp, tsm->parameterTypes)
+	{
+		Node	   *arg = (Node *) lfirst(larg);
+		Oid			argtype = lfirst_oid(ltyp);
+
+		arg = transformExpr(pstate, arg, EXPR_KIND_FROM_FUNCTION);
+		arg = coerce_to_specific_type(pstate, arg, argtype, "TABLESAMPLE");
+		assign_expr_collations(pstate, arg);
+		fargs = lappend(fargs, arg);
+	}
+	tablesample->args = fargs;
+
+	/* Process REPEATABLE (seed) */
+	if (rts->repeatable != NULL)
+	{
+		Node	   *arg;
+
+		if (!tsm->repeatable_across_queries)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("tablesample method %s does not support REPEATABLE",
+							NameListToString(rts->method)),
+					 parser_errposition(pstate, rts->location)));
+
+		arg = transformExpr(pstate, rts->repeatable, EXPR_KIND_FROM_FUNCTION);
+		arg = coerce_to_specific_type(pstate, arg, FLOAT8OID, "REPEATABLE");
+		assign_expr_collations(pstate, arg);
+		tablesample->repeatable = (Expr *) arg;
+	}
+	else
+		tablesample->repeatable = NULL;
+
+	return tablesample;
+}
+
+/*
+ * getNSItemForSpecialRelationTypes
+ *
+ * If given RangeVar refers to a CTE or an EphemeralNamedRelation,
+ * build and return an appropriate ParseNamespaceItem, otherwise return NULL
+ */
+static ParseNamespaceItem *
+getNSItemForSpecialRelationTypes(ParseState *pstate, RangeVar *rv)
+{
+	ParseNamespaceItem *nsitem;
+	CommonTableExpr *cte;
+	Index		levelsup;
+
+	/*
+	 * if it is a qualified name, it can't be a CTE or tuplestore reference
+	 */
+	if (rv->schemaname)
+		return NULL;
+
+	cte = scanNameSpaceForCTE(pstate, rv->relname, &levelsup);
+	if (cte)
+		nsitem = addRangeTableEntryForCTE(pstate, cte, levelsup, rv, true);
+	else if (scanNameSpaceForENR(pstate, rv->relname))
+		nsitem = addRangeTableEntryForENR(pstate, rv, true);
+	else
+		nsitem = NULL;
+
+	return nsitem;
+}
+
+/*
+ * transformFromClauseItem -
+ *	  Transform a FROM-clause item, adding any required entries to the
+ *	  range table list being built in the ParseState, and return the
+ *	  transformed item ready to include in the joinlist.  Also build a
+ *	  ParseNamespaceItem list describing the names exposed by this item.
+ *	  This routine can recurse to handle SQL92 JOIN expressions.
+ *
+ * The function return value is the node to add to the jointree (a
+ * RangeTblRef or JoinExpr).  Additional output parameters are:
+ *
+ * *top_nsitem: receives the ParseNamespaceItem directly corresponding to the
+ * jointree item.  (This is only used during internal recursion, not by
+ * outside callers.)
+ *
+ * *namespace: receives a List of ParseNamespaceItems for the RTEs exposed
+ * as table/column names by this item.  (The lateral_only flags in these items
+ * are indeterminate and should be explicitly set by the caller before use.)
+ */
+static Node *
+transformFromClauseItem(ParseState *pstate, Node *n,
+						ParseNamespaceItem **top_nsitem,
+						List **namespace)
+{
+	/* Guard against stack overflow due to overly deep subtree */
+	check_stack_depth();
+
+	if (IsA(n, RangeVar))
+	{
+		/* Plain relation reference, or perhaps a CTE reference */
+		RangeVar   *rv = (RangeVar *) n;
+		RangeTblRef *rtr;
+		ParseNamespaceItem *nsitem;
+
+		/* Check if it's a CTE or tuplestore reference */
+		nsitem = getNSItemForSpecialRelationTypes(pstate, rv);
+
+		/* if not found above, must be a table reference */
+		if (!nsitem)
+			nsitem = transformTableEntry(pstate, rv);
+
+		*top_nsitem = nsitem;
+		*namespace = list_make1(nsitem);
+		rtr = makeNode(RangeTblRef);
+		rtr->rtindex = nsitem->p_rtindex;
+		return (Node *) rtr;
+	}
+	else if (IsA(n, RangeSubselect))
+	{
+		/* sub-SELECT is like a plain relation */
+		RangeTblRef *rtr;
+		ParseNamespaceItem *nsitem;
+
+		nsitem = transformRangeSubselect(pstate, (RangeSubselect *) n);
+		*top_nsitem = nsitem;
+		*namespace = list_make1(nsitem);
+		rtr = makeNode(RangeTblRef);
+		rtr->rtindex = nsitem->p_rtindex;
+		return (Node *) rtr;
+	}
+	else if (IsA(n, RangeFunction))
+	{
+		/* function is like a plain relation */
+		RangeTblRef *rtr;
+		ParseNamespaceItem *nsitem;
+
+		nsitem = transformRangeFunction(pstate, (RangeFunction *) n);
+		*top_nsitem = nsitem;
+		*namespace = list_make1(nsitem);
+		rtr = makeNode(RangeTblRef);
+		rtr->rtindex = nsitem->p_rtindex;
+		return (Node *) rtr;
+	}
+	else if (IsA(n, RangeTableFunc))
+	{
+		/* table function is like a plain relation */
+		RangeTblRef *rtr;
+		ParseNamespaceItem *nsitem;
+
+		nsitem = transformRangeTableFunc(pstate, (RangeTableFunc *) n);
+		*top_nsitem = nsitem;
+		*namespace = list_make1(nsitem);
+		rtr = makeNode(RangeTblRef);
+		rtr->rtindex = nsitem->p_rtindex;
+		return (Node *) rtr;
+	}
+	else if (IsA(n, RangeTableSample))
+	{
+		/* TABLESAMPLE clause (wrapping some other valid FROM node) */
+		RangeTableSample *rts = (RangeTableSample *) n;
+		Node	   *rel;
+		RangeTblEntry *rte;
+
+		/* Recursively transform the contained relation */
+		rel = transformFromClauseItem(pstate, rts->relation,
+									  top_nsitem, namespace);
+		rte = (*top_nsitem)->p_rte;
+		/* We only support this on plain relations and matviews */
+		if (rte->rtekind != RTE_RELATION ||
+			(rte->relkind != RELKIND_RELATION &&
+			 rte->relkind != RELKIND_MATVIEW &&
+			 rte->relkind != RELKIND_PARTITIONED_TABLE))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("TABLESAMPLE clause can only be applied to tables and materialized views"),
+					 parser_errposition(pstate, exprLocation(rts->relation))));
+
+		/* Transform TABLESAMPLE details and attach to the RTE */
+		rte->tablesample = transformRangeTableSample(pstate, rts);
+		return rel;
+	}
+	else if (IsA(n, JoinExpr))
+	{
+		/* A newfangled join expression */
+		JoinExpr   *j = (JoinExpr *) n;
+		ParseNamespaceItem *nsitem;
+		ParseNamespaceItem *l_nsitem;
+		ParseNamespaceItem *r_nsitem;
+		List	   *l_namespace,
+				   *r_namespace,
+				   *my_namespace,
+				   *l_colnames,
+				   *r_colnames,
+				   *res_colnames,
+				   *l_colnos,
+				   *r_colnos,
+				   *res_colvars;
+		ParseNamespaceColumn *l_nscolumns,
+				   *r_nscolumns,
+				   *res_nscolumns;
+		int			res_colindex;
+		bool		lateral_ok;
+		int			sv_namespace_length;
+		int			k;
+
+		/*
+		 * Recursively process the left subtree, then the right.  We must do
+		 * it in this order for correct visibility of LATERAL references.
+		 */
+		j->larg = transformFromClauseItem(pstate, j->larg,
+										  &l_nsitem,
+										  &l_namespace);
+
+		/*
+		 * Make the left-side RTEs available for LATERAL access within the
+		 * right side, by temporarily adding them to the pstate's namespace
+		 * list.  Per SQL:2008, if the join type is not INNER or LEFT then the
+		 * left-side names must still be exposed, but it's an error to
+		 * reference them.  (Stupid design, but that's what it says.)  Hence,
+		 * we always push them into the namespace, but mark them as not
+		 * lateral_ok if the jointype is wrong.
+		 *
+		 * Notice that we don't require the merged namespace list to be
+		 * conflict-free.  See the comments for scanNameSpaceForRefname().
+		 */
+		lateral_ok = (j->jointype == JOIN_INNER || j->jointype == JOIN_LEFT);
+		setNamespaceLateralState(l_namespace, true, lateral_ok);
+
+		sv_namespace_length = list_length(pstate->p_namespace);
+		pstate->p_namespace = list_concat(pstate->p_namespace, l_namespace);
+
+		/* And now we can process the RHS */
+		j->rarg = transformFromClauseItem(pstate, j->rarg,
+										  &r_nsitem,
+										  &r_namespace);
+
+		/* Remove the left-side RTEs from the namespace list again */
+		pstate->p_namespace = list_truncate(pstate->p_namespace,
+											sv_namespace_length);
+
+		/*
+		 * Check for conflicting refnames in left and right subtrees. Must do
+		 * this because higher levels will assume I hand back a self-
+		 * consistent namespace list.
+		 */
+		checkNameSpaceConflicts(pstate, l_namespace, r_namespace);
+
+		/*
+		 * Generate combined namespace info for possible use below.
+		 */
+		my_namespace = list_concat(l_namespace, r_namespace);
+
+		/*
+		 * We'll work from the nscolumns data and eref alias column names for
+		 * each of the input nsitems.  Note that these include dropped
+		 * columns, which is helpful because we can keep track of physical
+		 * input column numbers more easily.
+		 */
+		l_nscolumns = l_nsitem->p_nscolumns;
+		l_colnames = l_nsitem->p_names->colnames;
+		r_nscolumns = r_nsitem->p_nscolumns;
+		r_colnames = r_nsitem->p_names->colnames;
+
+		/*
+		 * Natural join does not explicitly specify columns; must generate
+		 * columns to join. Need to run through the list of columns from each
+		 * table or join result and match up the column names. Use the first
+		 * table, and check every column in the second table for a match.
+		 * (We'll check that the matches were unique later on.) The result of
+		 * this step is a list of column names just like an explicitly-written
+		 * USING list.
+		 */
+		if (j->isNatural)
+		{
+			List	   *rlist = NIL;
+			ListCell   *lx,
+					   *rx;
+
+			Assert(j->usingClause == NIL);	/* shouldn't have USING() too */
+
+			foreach(lx, l_colnames)
+			{
+				char	   *l_colname = strVal(lfirst(lx));
+				String	   *m_name = NULL;
+
+				if (l_colname[0] == '\0')
+					continue;	/* ignore dropped columns */
+
+				foreach(rx, r_colnames)
+				{
+					char	   *r_colname = strVal(lfirst(rx));
+
+					if (strcmp(l_colname, r_colname) == 0)
+					{
+						m_name = makeString(l_colname);
+						break;
+					}
+				}
+
+				/* matched a right column? then keep as join column... */
+				if (m_name != NULL)
+					rlist = lappend(rlist, m_name);
+			}
+
+			j->usingClause = rlist;
+		}
+
+		/*
+		 * If a USING clause alias was specified, save the USING columns as
+		 * its column list.
+		 */
+		if (j->join_using_alias)
+			j->join_using_alias->colnames = j->usingClause;
+
+		/*
+		 * Now transform the join qualifications, if any.
+		 */
+		l_colnos = NIL;
+		r_colnos = NIL;
+		res_colnames = NIL;
+		res_colvars = NIL;
+
+		/* this may be larger than needed, but it's not worth being exact */
+		res_nscolumns = (ParseNamespaceColumn *)
+			palloc0((list_length(l_colnames) + list_length(r_colnames)) *
+					sizeof(ParseNamespaceColumn));
+		res_colindex = 0;
+
+		if (j->usingClause)
+		{
+			/*
+			 * JOIN/USING (or NATURAL JOIN, as transformed above). Transform
+			 * the list into an explicit ON-condition, and generate a list of
+			 * merged result columns.
+			 */
+			List	   *ucols = j->usingClause;
+			List	   *l_usingvars = NIL;
+			List	   *r_usingvars = NIL;
+			ListCell   *ucol;
+
+			Assert(j->quals == NULL);	/* shouldn't have ON() too */
+
+			foreach(ucol, ucols)
+			{
+				char	   *u_colname = strVal(lfirst(ucol));
+				ListCell   *col;
+				int			ndx;
+				int			l_index = -1;
+				int			r_index = -1;
+				Var		   *l_colvar,
+						   *r_colvar;
+				Node	   *u_colvar;
+				ParseNamespaceColumn *res_nscolumn;
+
+				Assert(u_colname[0] != '\0');
+
+				/* Check for USING(foo,foo) */
+				foreach(col, res_colnames)
+				{
+					char	   *res_colname = strVal(lfirst(col));
+
+					if (strcmp(res_colname, u_colname) == 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_DUPLICATE_COLUMN),
+								 errmsg("column name \"%s\" appears more than once in USING clause",
+										u_colname)));
+				}
+
+				/* Find it in left input */
+				ndx = 0;
+				foreach(col, l_colnames)
+				{
+					char	   *l_colname = strVal(lfirst(col));
+
+					if (strcmp(l_colname, u_colname) == 0)
+					{
+						if (l_index >= 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_AMBIGUOUS_COLUMN),
+									 errmsg("common column name \"%s\" appears more than once in left table",
+											u_colname)));
+						l_index = ndx;
+					}
+					ndx++;
+				}
+				if (l_index < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_UNDEFINED_COLUMN),
+							 errmsg("column \"%s\" specified in USING clause does not exist in left table",
+									u_colname)));
+				l_colnos = lappend_int(l_colnos, l_index + 1);
+
+				/* Find it in right input */
+				ndx = 0;
+				foreach(col, r_colnames)
+				{
+					char	   *r_colname = strVal(lfirst(col));
+
+					if (strcmp(r_colname, u_colname) == 0)
+					{
+						if (r_index >= 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_AMBIGUOUS_COLUMN),
+									 errmsg("common column name \"%s\" appears more than once in right table",
+											u_colname)));
+						r_index = ndx;
+					}
+					ndx++;
+				}
+				if (r_index < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_UNDEFINED_COLUMN),
+							 errmsg("column \"%s\" specified in USING clause does not exist in right table",
+									u_colname)));
+				r_colnos = lappend_int(r_colnos, r_index + 1);
+
+				l_colvar = buildVarFromNSColumn(l_nscolumns + l_index);
+				l_usingvars = lappend(l_usingvars, l_colvar);
+				r_colvar = buildVarFromNSColumn(r_nscolumns + r_index);
+				r_usingvars = lappend(r_usingvars, r_colvar);
+
+				res_colnames = lappend(res_colnames, lfirst(ucol));
+				u_colvar = buildMergedJoinVar(pstate,
+											  j->jointype,
+											  l_colvar,
+											  r_colvar);
+				res_colvars = lappend(res_colvars, u_colvar);
+				res_nscolumn = res_nscolumns + res_colindex;
+				res_colindex++;
+				if (u_colvar == (Node *) l_colvar)
+				{
+					/* Merged column is equivalent to left input */
+					*res_nscolumn = l_nscolumns[l_index];
+				}
+				else if (u_colvar == (Node *) r_colvar)
+				{
+					/* Merged column is equivalent to right input */
+					*res_nscolumn = r_nscolumns[r_index];
+				}
+				else
+				{
+					/*
+					 * Merged column is not semantically equivalent to either
+					 * input, so it needs to be referenced as the join output
+					 * column.  We don't know the join's varno yet, so we'll
+					 * replace these zeroes below.
+					 */
+					res_nscolumn->p_varno = 0;
+					res_nscolumn->p_varattno = res_colindex;
+					res_nscolumn->p_vartype = exprType(u_colvar);
+					res_nscolumn->p_vartypmod = exprTypmod(u_colvar);
+					res_nscolumn->p_varcollid = exprCollation(u_colvar);
+					res_nscolumn->p_varnosyn = 0;
+					res_nscolumn->p_varattnosyn = res_colindex;
+				}
+			}
+
+			j->quals = transformJoinUsingClause(pstate,
+												l_usingvars,
+												r_usingvars);
+		}
+		else if (j->quals)
+		{
+			/* User-written ON-condition; transform it */
+			j->quals = transformJoinOnClause(pstate, j, my_namespace);
+		}
+		else
+		{
+			/* CROSS JOIN: no quals */
+		}
+
+		/* Add remaining columns from each side to the output columns */
+		res_colindex +=
+			extractRemainingColumns(l_nscolumns, l_colnames, &l_colnos,
+									&res_colnames, &res_colvars,
+									res_nscolumns + res_colindex);
+		res_colindex +=
+			extractRemainingColumns(r_nscolumns, r_colnames, &r_colnos,
+									&res_colnames, &res_colvars,
+									res_nscolumns + res_colindex);
+
+		/*
+		 * Now build an RTE and nsitem for the result of the join.
+		 * res_nscolumns isn't totally done yet, but that's OK because
+		 * addRangeTableEntryForJoin doesn't examine it, only store a pointer.
+		 */
+		nsitem = addRangeTableEntryForJoin(pstate,
+										   res_colnames,
+										   res_nscolumns,
+										   j->jointype,
+										   list_length(j->usingClause),
+										   res_colvars,
+										   l_colnos,
+										   r_colnos,
+										   j->join_using_alias,
+										   j->alias,
+										   true);
+
+		j->rtindex = nsitem->p_rtindex;
+
+		/*
+		 * Now that we know the join RTE's rangetable index, we can fix up the
+		 * res_nscolumns data in places where it should contain that.
+		 */
+		Assert(res_colindex == list_length(nsitem->p_names->colnames));
+		for (k = 0; k < res_colindex; k++)
+		{
+			ParseNamespaceColumn *nscol = res_nscolumns + k;
+
+			/* fill in join RTI for merged columns */
+			if (nscol->p_varno == 0)
+				nscol->p_varno = j->rtindex;
+			if (nscol->p_varnosyn == 0)
+				nscol->p_varnosyn = j->rtindex;
+			/* if join has an alias, it syntactically hides all inputs */
+			if (j->alias)
+			{
+				nscol->p_varnosyn = j->rtindex;
+				nscol->p_varattnosyn = k + 1;
+			}
+		}
+
+		/* make a matching link to the JoinExpr for later use */
+		for (k = list_length(pstate->p_joinexprs) + 1; k < j->rtindex; k++)
+			pstate->p_joinexprs = lappend(pstate->p_joinexprs, NULL);
+		pstate->p_joinexprs = lappend(pstate->p_joinexprs, j);
+		Assert(list_length(pstate->p_joinexprs) == j->rtindex);
+
+		/*
+		 * If the join has a USING alias, build a ParseNamespaceItem for that
+		 * and add it to the list of nsitems in the join's input.
+		 */
+		if (j->join_using_alias)
+		{
+			ParseNamespaceItem *jnsitem;
+
+			jnsitem = (ParseNamespaceItem *) palloc(sizeof(ParseNamespaceItem));
+			jnsitem->p_names = j->join_using_alias;
+			jnsitem->p_rte = nsitem->p_rte;
+			jnsitem->p_rtindex = nsitem->p_rtindex;
+			/* no need to copy the first N columns, just use res_nscolumns */
+			jnsitem->p_nscolumns = res_nscolumns;
+			/* set default visibility flags; might get changed later */
+			jnsitem->p_rel_visible = true;
+			jnsitem->p_cols_visible = true;
+			jnsitem->p_lateral_only = false;
+			jnsitem->p_lateral_ok = true;
+			/* Per SQL, we must check for alias conflicts */
+			checkNameSpaceConflicts(pstate, list_make1(jnsitem), my_namespace);
+			my_namespace = lappend(my_namespace, jnsitem);
+		}
+
+		/*
+		 * Prepare returned namespace list.  If the JOIN has an alias then it
+		 * hides the contained RTEs completely; otherwise, the contained RTEs
+		 * are still visible as table names, but are not visible for
+		 * unqualified column-name access.
+		 *
+		 * Note: if there are nested alias-less JOINs, the lower-level ones
+		 * will remain in the list although they have neither p_rel_visible
+		 * nor p_cols_visible set.  We could delete such list items, but it's
+		 * unclear that it's worth expending cycles to do so.
+		 */
+		if (j->alias != NULL)
+			my_namespace = NIL;
+		else
+			setNamespaceColumnVisibility(my_namespace, false);
+
+		/*
+		 * The join RTE itself is always made visible for unqualified column
+		 * names.  It's visible as a relation name only if it has an alias.
+		 */
+		nsitem->p_rel_visible = (j->alias != NULL);
+		nsitem->p_cols_visible = true;
+		nsitem->p_lateral_only = false;
+		nsitem->p_lateral_ok = true;
+
+		*top_nsitem = nsitem;
+		*namespace = lappend(my_namespace, nsitem);
+
+		return (Node *) j;
+	}
+	else
+		elog(ERROR, "unrecognized node type: %d", (int) nodeTag(n));
+	return NULL;				/* can't get here, keep compiler quiet */
+}
+
+/*
+ * buildVarFromNSColumn -
+ *	  build a Var node using ParseNamespaceColumn data
+ *
+ * We assume varlevelsup should be 0, and no location is specified
+ */
+static Var *
+buildVarFromNSColumn(ParseNamespaceColumn *nscol)
+{
+	Var		   *var;
+
+	Assert(nscol->p_varno > 0); /* i.e., not deleted column */
+	var = makeVar(nscol->p_varno,
+				  nscol->p_varattno,
+				  nscol->p_vartype,
+				  nscol->p_vartypmod,
+				  nscol->p_varcollid,
+				  0);
+	/* makeVar doesn't offer parameters for these, so set by hand: */
+	var->varnosyn = nscol->p_varnosyn;
+	var->varattnosyn = nscol->p_varattnosyn;
+	return var;
+}
+
+/*
+ * buildMergedJoinVar -
+ *	  generate a suitable replacement expression for a merged join column
+ */
+static Node *
+buildMergedJoinVar(ParseState *pstate, JoinType jointype,
+				   Var *l_colvar, Var *r_colvar)
+{
+	Oid			outcoltype;
+	int32		outcoltypmod;
+	Node	   *l_node,
+			   *r_node,
+			   *res_node;
+
+	outcoltype = select_common_type(pstate,
+									list_make2(l_colvar, r_colvar),
+									"JOIN/USING",
+									NULL);
+	outcoltypmod = select_common_typmod(pstate,
+										list_make2(l_colvar, r_colvar),
+										outcoltype);
+
+	/*
+	 * Insert coercion functions if needed.  Note that a difference in typmod
+	 * can only happen if input has typmod but outcoltypmod is -1. In that
+	 * case we insert a RelabelType to clearly mark that result's typmod is
+	 * not same as input.  We never need coerce_type_typmod.
+	 */
+	if (l_colvar->vartype != outcoltype)
+		l_node = coerce_type(pstate, (Node *) l_colvar, l_colvar->vartype,
+							 outcoltype, outcoltypmod,
+							 COERCION_IMPLICIT, COERCE_IMPLICIT_CAST, -1);
+	else if (l_colvar->vartypmod != outcoltypmod)
+		l_node = (Node *) makeRelabelType((Expr *) l_colvar,
+										  outcoltype, outcoltypmod,
+										  InvalidOid,	/* fixed below */
+										  COERCE_IMPLICIT_CAST);
+	else
+		l_node = (Node *) l_colvar;
+
+	if (r_colvar->vartype != outcoltype)
+		r_node = coerce_type(pstate, (Node *) r_colvar, r_colvar->vartype,
+							 outcoltype, outcoltypmod,
+							 COERCION_IMPLICIT, COERCE_IMPLICIT_CAST, -1);
+	else if (r_colvar->vartypmod != outcoltypmod)
+		r_node = (Node *) makeRelabelType((Expr *) r_colvar,
+										  outcoltype, outcoltypmod,
+										  InvalidOid,	/* fixed below */
+										  COERCE_IMPLICIT_CAST);
+	else
+		r_node = (Node *) r_colvar;
+
+	/*
+	 * Choose what to emit
+	 */
+	switch (jointype)
+	{
+		case JOIN_INNER:
+
+			/*
+			 * We can use either var; prefer non-coerced one if available.
+			 */
+			if (IsA(l_node, Var))
+				res_node = l_node;
+			else if (IsA(r_node, Var))
+				res_node = r_node;
+			else
+				res_node = l_node;
+			break;
+		case JOIN_LEFT:
+			/* Always use left var */
+			res_node = l_node;
+			break;
+		case JOIN_RIGHT:
+			/* Always use right var */
+			res_node = r_node;
+			break;
+		case JOIN_FULL:
+			{
+				/*
+				 * Here we must build a COALESCE expression to ensure that the
+				 * join output is non-null if either input is.
+				 */
+				CoalesceExpr *c = makeNode(CoalesceExpr);
+
+				c->coalescetype = outcoltype;
+				/* coalescecollid will get set below */
+				c->args = list_make2(l_node, r_node);
+				c->location = -1;
+				res_node = (Node *) c;
+				break;
+			}
+		default:
+			elog(ERROR, "unrecognized join type: %d", (int) jointype);
+			res_node = NULL;	/* keep compiler quiet */
+			break;
+	}
+
+	/*
+	 * Apply assign_expr_collations to fix up the collation info in the
+	 * coercion and CoalesceExpr nodes, if we made any.  This must be done now
+	 * so that the join node's alias vars show correct collation info.
+	 */
+	assign_expr_collations(pstate, res_node);
+
+	return res_node;
+}
+
+/*
+ * setNamespaceColumnVisibility -
+ *	  Convenience subroutine to update cols_visible flags in a namespace list.
+ */
+static void
+setNamespaceColumnVisibility(List *namespace, bool cols_visible)
+{
+	ListCell   *lc;
+
+	foreach(lc, namespace)
+	{
+		ParseNamespaceItem *nsitem = (ParseNamespaceItem *) lfirst(lc);
+
+		nsitem->p_cols_visible = cols_visible;
+	}
+}
+
+/*
+ * setNamespaceLateralState -
+ *	  Convenience subroutine to update LATERAL flags in a namespace list.
+ */
+static void
+setNamespaceLateralState(List *namespace, bool lateral_only, bool lateral_ok)
+{
+	ListCell   *lc;
+
+	foreach(lc, namespace)
+	{
+		ParseNamespaceItem *nsitem = (ParseNamespaceItem *) lfirst(lc);
+
+		nsitem->p_lateral_only = lateral_only;
+		nsitem->p_lateral_ok = lateral_ok;
+	}
+}
+
+
+/*
+ * transformWhereClause -
+ *	  Transform the qualification and make sure it is of type boolean.
+ *	  Used for WHERE and allied clauses.
+ *
+ * constructName does not affect the semantics, but is used in error messages
+ */
+Node *
+transformWhereClause(ParseState *pstate, Node *clause,
+					 ParseExprKind exprKind, const char *constructName)
+{
+	Node	   *qual;
+
+	if (clause == NULL)
+		return NULL;
+
+	qual = transformExpr(pstate, clause, exprKind);
+
+	qual = coerce_to_boolean(pstate, qual, constructName);
+
+	return qual;
+}
+
+
+/*
+ * transformLimitClause -
+ *	  Transform the expression and make sure it is of type bigint.
+ *	  Used for LIMIT and allied clauses.
+ *
+ * Note: as of Postgres 8.2, LIMIT expressions are expected to yield int8,
+ * rather than int4 as before.
+ *
+ * constructName does not affect the semantics, but is used in error messages
+ */
+Node *
+transformLimitClause(ParseState *pstate, Node *clause,
+					 ParseExprKind exprKind, const char *constructName,
+					 LimitOption limitOption)
+{
+	Node	   *qual;
+
+	if (clause == NULL)
+		return NULL;
+
+	qual = transformExpr(pstate, clause, exprKind);
+
+	qual = coerce_to_specific_type(pstate, qual, INT8OID, constructName);
+
+	/* LIMIT can't refer to any variables of the current query */
+	checkExprIsVarFree(pstate, qual, constructName);
+
+	/*
+	 * Don't allow NULLs in FETCH FIRST .. WITH TIES.  This test is ugly and
+	 * extremely simplistic, in that you can pass a NULL anyway by hiding it
+	 * inside an expression -- but this protects ruleutils against emitting an
+	 * unadorned NULL that's not accepted back by the grammar.
+	 */
+	if (exprKind == EXPR_KIND_LIMIT && limitOption == LIMIT_OPTION_WITH_TIES &&
+		IsA(clause, A_Const) && castNode(A_Const, clause)->isnull)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_ROW_COUNT_IN_LIMIT_CLAUSE),
+				 errmsg("row count cannot be null in FETCH FIRST ... WITH TIES clause")));
+
+	return qual;
+}
+
+/*
+ * checkExprIsVarFree
+ *		Check that given expr has no Vars of the current query level
+ *		(aggregates and window functions should have been rejected already).
+ *
+ * This is used to check expressions that have to have a consistent value
+ * across all rows of the query, such as a LIMIT.  Arguably it should reject
+ * volatile functions, too, but we don't do that --- whatever value the
+ * function gives on first execution is what you get.
+ *
+ * constructName does not affect the semantics, but is used in error messages
+ */
+static void
+checkExprIsVarFree(ParseState *pstate, Node *n, const char *constructName)
+{
+	if (contain_vars_of_level(n, 0))
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
+		/* translator: %s is name of a SQL construct, eg LIMIT */
+				 errmsg("argument of %s must not contain variables",
+						constructName),
+				 parser_errposition(pstate,
+									locate_var_of_level(n, 0))));
+	}
+}
+
+
+/*
+ * checkTargetlistEntrySQL92 -
+ *	  Validate a targetlist entry found by findTargetlistEntrySQL92
+ *
+ * When we select a pre-existing tlist entry as a result of syntax such
+ * as "GROUP BY 1", we have to make sure it is acceptable for use in the
+ * indicated clause type; transformExpr() will have treated it as a regular
+ * targetlist item.
+ */
+static void
+checkTargetlistEntrySQL92(ParseState *pstate, TargetEntry *tle,
+						  ParseExprKind exprKind)
+{
+	switch (exprKind)
+	{
+		case EXPR_KIND_GROUP_BY:
+			/* reject aggregates and window functions */
+			if (pstate->p_hasAggs &&
+				contain_aggs_of_level((Node *) tle->expr, 0))
+				ereport(ERROR,
+						(errcode(ERRCODE_GROUPING_ERROR),
+				/* translator: %s is name of a SQL construct, eg GROUP BY */
+						 errmsg("aggregate functions are not allowed in %s",
+								ParseExprKindName(exprKind)),
+						 parser_errposition(pstate,
+											locate_agg_of_level((Node *) tle->expr, 0))));
+			if (pstate->p_hasWindowFuncs &&
+				contain_windowfuncs((Node *) tle->expr))
+				ereport(ERROR,
+						(errcode(ERRCODE_WINDOWING_ERROR),
+				/* translator: %s is name of a SQL construct, eg GROUP BY */
+						 errmsg("window functions are not allowed in %s",
+								ParseExprKindName(exprKind)),
+						 parser_errposition(pstate,
+											locate_windowfunc((Node *) tle->expr))));
+			break;
+		case EXPR_KIND_ORDER_BY:
+			/* no extra checks needed */
+			break;
+		case EXPR_KIND_DISTINCT_ON:
+			/* no extra checks needed */
+			break;
+		default:
+			elog(ERROR, "unexpected exprKind in checkTargetlistEntrySQL92");
+			break;
+	}
+}
+
+/*
+ *	findTargetlistEntrySQL92 -
+ *	  Returns the targetlist entry matching the given (untransformed) node.
+ *	  If no matching entry exists, one is created and appended to the target
+ *	  list as a "resjunk" node.
+ *
+ * This function supports the old SQL92 ORDER BY interpretation, where the
+ * expression is an output column name or number.  If we fail to find a
+ * match of that sort, we fall through to the SQL99 rules.  For historical
+ * reasons, Postgres also allows this interpretation for GROUP BY, though
+ * the standard never did.  However, for GROUP BY we prefer a SQL99 match.
+ * This function is *not* used for WINDOW definitions.
+ *
+ * node		the ORDER BY, GROUP BY, or DISTINCT ON expression to be matched
+ * tlist	the target list (passed by reference so we can append to it)
+ * exprKind identifies clause type being processed
+ */
+static TargetEntry *
+findTargetlistEntrySQL92(ParseState *pstate, Node *node, List **tlist,
+						 ParseExprKind exprKind)
+{
+	ListCell   *tl;
+
+	/*----------
+	 * Handle two special cases as mandated by the SQL92 spec:
+	 *
+	 * 1. Bare ColumnName (no qualifier or subscripts)
+	 *	  For a bare identifier, we search for a matching column name
+	 *	  in the existing target list.  Multiple matches are an error
+	 *	  unless they refer to identical values; for example,
+	 *	  we allow	SELECT a, a FROM table ORDER BY a
+	 *	  but not	SELECT a AS b, b FROM table ORDER BY b
+	 *	  If no match is found, we fall through and treat the identifier
+	 *	  as an expression.
+	 *	  For GROUP BY, it is incorrect to match the grouping item against
+	 *	  targetlist entries: according to SQL92, an identifier in GROUP BY
+	 *	  is a reference to a column name exposed by FROM, not to a target
+	 *	  list column.  However, many implementations (including pre-7.0
+	 *	  PostgreSQL) accept this anyway.  So for GROUP BY, we look first
+	 *	  to see if the identifier matches any FROM column name, and only
+	 *	  try for a targetlist name if it doesn't.  This ensures that we
+	 *	  adhere to the spec in the case where the name could be both.
+	 *	  DISTINCT ON isn't in the standard, so we can do what we like there;
+	 *	  we choose to make it work like ORDER BY, on the rather flimsy
+	 *	  grounds that ordinary DISTINCT works on targetlist entries.
+	 *
+	 * 2. IntegerConstant
+	 *	  This means to use the n'th item in the existing target list.
+	 *	  Note that it would make no sense to order/group/distinct by an
+	 *	  actual constant, so this does not create a conflict with SQL99.
+	 *	  GROUP BY column-number is not allowed by SQL92, but since
+	 *	  the standard has no other behavior defined for this syntax,
+	 *	  we may as well accept this common extension.
+	 *
+	 * Note that pre-existing resjunk targets must not be used in either case,
+	 * since the user didn't write them in his SELECT list.
+	 *
+	 * If neither special case applies, fall through to treat the item as
+	 * an expression per SQL99.
+	 *----------
+	 */
+	if (IsA(node, ColumnRef) &&
+		list_length(((ColumnRef *) node)->fields) == 1 &&
+		IsA(linitial(((ColumnRef *) node)->fields), String))
+	{
+		char	   *name = strVal(linitial(((ColumnRef *) node)->fields));
+		int			location = ((ColumnRef *) node)->location;
+
+		if (exprKind == EXPR_KIND_GROUP_BY)
+		{
+			/*
+			 * In GROUP BY, we must prefer a match against a FROM-clause
+			 * column to one against the targetlist.  Look to see if there is
+			 * a matching column.  If so, fall through to use SQL99 rules.
+			 * NOTE: if name could refer ambiguously to more than one column
+			 * name exposed by FROM, colNameToVar will ereport(ERROR). That's
+			 * just what we want here.
+			 *
+			 * Small tweak for 7.4.3: ignore matches in upper query levels.
+			 * This effectively changes the search order for bare names to (1)
+			 * local FROM variables, (2) local targetlist aliases, (3) outer
+			 * FROM variables, whereas before it was (1) (3) (2). SQL92 and
+			 * SQL99 do not allow GROUPing BY an outer reference, so this
+			 * breaks no cases that are legal per spec, and it seems a more
+			 * self-consistent behavior.
+			 */
+			if (colNameToVar(pstate, name, true, location) != NULL)
+				name = NULL;
+		}
+
+		if (name != NULL)
+		{
+			TargetEntry *target_result = NULL;
+
+			foreach(tl, *tlist)
+			{
+				TargetEntry *tle = (TargetEntry *) lfirst(tl);
+
+				if (!tle->resjunk &&
+					strcmp(tle->resname, name) == 0)
+				{
+					if (target_result != NULL)
+					{
+						if (!equal(target_result->expr, tle->expr))
+							ereport(ERROR,
+									(errcode(ERRCODE_AMBIGUOUS_COLUMN),
+
+							/*------
+							  translator: first %s is name of a SQL construct, eg ORDER BY */
+									 errmsg("%s \"%s\" is ambiguous",
+											ParseExprKindName(exprKind),
+											name),
+									 parser_errposition(pstate, location)));
+					}
+					else
+						target_result = tle;
+					/* Stay in loop to check for ambiguity */
+				}
+			}
+			if (target_result != NULL)
+			{
+				/* return the first match, after suitable validation */
+				checkTargetlistEntrySQL92(pstate, target_result, exprKind);
+				return target_result;
+			}
+		}
+	}
+	if (IsA(node, A_Const))
+	{
+		A_Const    *aconst = castNode(A_Const, node);
+		int			targetlist_pos = 0;
+		int			target_pos;
+
+		if (!IsA(&aconst->val, Integer))
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+			/* translator: %s is name of a SQL construct, eg ORDER BY */
+					 errmsg("non-integer constant in %s",
+							ParseExprKindName(exprKind)),
+					 parser_errposition(pstate, aconst->location)));
+
+		target_pos = intVal(&aconst->val);
+		foreach(tl, *tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(tl);
+
+			if (!tle->resjunk)
+			{
+				if (++targetlist_pos == target_pos)
+				{
+					/* return the unique match, after suitable validation */
+					checkTargetlistEntrySQL92(pstate, tle, exprKind);
+					return tle;
+				}
+			}
+		}
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
+		/* translator: %s is name of a SQL construct, eg ORDER BY */
+				 errmsg("%s position %d is not in select list",
+						ParseExprKindName(exprKind), target_pos),
+				 parser_errposition(pstate, aconst->location)));
+	}
+
+	/*
+	 * Otherwise, we have an expression, so process it per SQL99 rules.
+	 */
+	return findTargetlistEntrySQL99(pstate, node, tlist, exprKind);
+}
+
+/*
+ *	findTargetlistEntrySQL99 -
+ *	  Returns the targetlist entry matching the given (untransformed) node.
+ *	  If no matching entry exists, one is created and appended to the target
+ *	  list as a "resjunk" node.
+ *
+ * This function supports the SQL99 interpretation, wherein the expression
+ * is just an ordinary expression referencing input column names.
+ *
+ * node		the ORDER BY, GROUP BY, etc expression to be matched
+ * tlist	the target list (passed by reference so we can append to it)
+ * exprKind identifies clause type being processed
+ */
+static TargetEntry *
+findTargetlistEntrySQL99(ParseState *pstate, Node *node, List **tlist,
+						 ParseExprKind exprKind)
+{
+	TargetEntry *target_result;
+	ListCell   *tl;
+	Node	   *expr;
+
+	/*
+	 * Convert the untransformed node to a transformed expression, and search
+	 * for a match in the tlist.  NOTE: it doesn't really matter whether there
+	 * is more than one match.  Also, we are willing to match an existing
+	 * resjunk target here, though the SQL92 cases above must ignore resjunk
+	 * targets.
+	 */
+	expr = transformExpr(pstate, node, exprKind);
+
+	foreach(tl, *tlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(tl);
+		Node	   *texpr;
+
+		/*
+		 * Ignore any implicit cast on the existing tlist expression.
+		 *
+		 * This essentially allows the ORDER/GROUP/etc item to adopt the same
+		 * datatype previously selected for a textually-equivalent tlist item.
+		 * There can't be any implicit cast at top level in an ordinary SELECT
+		 * tlist at this stage, but the case does arise with ORDER BY in an
+		 * aggregate function.
+		 */
+		texpr = strip_implicit_coercions((Node *) tle->expr);
+
+		if (equal(expr, texpr))
+			return tle;
+	}
+
+	/*
+	 * If no matches, construct a new target entry which is appended to the
+	 * end of the target list.  This target is given resjunk = true so that it
+	 * will not be projected into the final tuple.
+	 */
+	target_result = transformTargetEntry(pstate, node, expr, exprKind,
+										 NULL, true);
+
+	*tlist = lappend(*tlist, target_result);
+
+	return target_result;
+}
+
+/*-------------------------------------------------------------------------
+ * Flatten out parenthesized sublists in grouping lists, and some cases
+ * of nested grouping sets.
+ *
+ * Inside a grouping set (ROLLUP, CUBE, or GROUPING SETS), we expect the
+ * content to be nested no more than 2 deep: i.e. ROLLUP((a,b),(c,d)) is
+ * ok, but ROLLUP((a,(b,c)),d) is flattened to ((a,b,c),d), which we then
+ * (later) normalize to ((a,b,c),(d)).
+ *
+ * CUBE or ROLLUP can be nested inside GROUPING SETS (but not the reverse),
+ * and we leave that alone if we find it. But if we see GROUPING SETS inside
+ * GROUPING SETS, we can flatten and normalize as follows:
+ *	 GROUPING SETS (a, (b,c), GROUPING SETS ((c,d),(e)), (f,g))
+ * becomes
+ *	 GROUPING SETS ((a), (b,c), (c,d), (e), (f,g))
+ *
+ * This is per the spec's syntax transformations, but these are the only such
+ * transformations we do in parse analysis, so that queries retain the
+ * originally specified grouping set syntax for CUBE and ROLLUP as much as
+ * possible when deparsed. (Full expansion of the result into a list of
+ * grouping sets is left to the planner.)
+ *
+ * When we're done, the resulting list should contain only these possible
+ * elements:
+ *	 - an expression
+ *	 - a CUBE or ROLLUP with a list of expressions nested 2 deep
+ *	 - a GROUPING SET containing any of:
+ *		- expression lists
+ *		- empty grouping sets
+ *		- CUBE or ROLLUP nodes with lists nested 2 deep
+ * The return is a new list, but doesn't deep-copy the old nodes except for
+ * GroupingSet nodes.
+ *
+ * As a side effect, flag whether the list has any GroupingSet nodes.
+ *-------------------------------------------------------------------------
+ */
+static Node *
+flatten_grouping_sets(Node *expr, bool toplevel, bool *hasGroupingSets)
+{
+	/* just in case of pathological input */
+	check_stack_depth();
+
+	if (expr == (Node *) NIL)
+		return (Node *) NIL;
+
+	switch (expr->type)
+	{
+		case T_RowExpr:
+			{
+				RowExpr    *r = (RowExpr *) expr;
+
+				if (r->row_format == COERCE_IMPLICIT_CAST)
+					return flatten_grouping_sets((Node *) r->args,
+												 false, NULL);
+			}
+			break;
+		case T_GroupingSet:
+			{
+				GroupingSet *gset = (GroupingSet *) expr;
+				ListCell   *l2;
+				List	   *result_set = NIL;
+
+				if (hasGroupingSets)
+					*hasGroupingSets = true;
+
+				/*
+				 * at the top level, we skip over all empty grouping sets; the
+				 * caller can supply the canonical GROUP BY () if nothing is
+				 * left.
+				 */
+
+				if (toplevel && gset->kind == GROUPING_SET_EMPTY)
+					return (Node *) NIL;
+
+				foreach(l2, gset->content)
+				{
+					Node	   *n1 = lfirst(l2);
+					Node	   *n2 = flatten_grouping_sets(n1, false, NULL);
+
+					if (IsA(n1, GroupingSet) &&
+						((GroupingSet *) n1)->kind == GROUPING_SET_SETS)
+						result_set = list_concat(result_set, (List *) n2);
+					else
+						result_set = lappend(result_set, n2);
+				}
+
+				/*
+				 * At top level, keep the grouping set node; but if we're in a
+				 * nested grouping set, then we need to concat the flattened
+				 * result into the outer list if it's simply nested.
+				 */
+
+				if (toplevel || (gset->kind != GROUPING_SET_SETS))
+				{
+					return (Node *) makeGroupingSet(gset->kind, result_set, gset->location);
+				}
+				else
+					return (Node *) result_set;
+			}
+		case T_List:
+			{
+				List	   *result = NIL;
+				ListCell   *l;
+
+				foreach(l, (List *) expr)
+				{
+					Node	   *n = flatten_grouping_sets(lfirst(l), toplevel, hasGroupingSets);
+
+					if (n != (Node *) NIL)
+					{
+						if (IsA(n, List))
+							result = list_concat(result, (List *) n);
+						else
+							result = lappend(result, n);
+					}
+				}
+
+				return (Node *) result;
+			}
+		default:
+			break;
+	}
+
+	return expr;
+}
+
+/*
+ * Transform a single expression within a GROUP BY clause or grouping set.
+ *
+ * The expression is added to the targetlist if not already present, and to the
+ * flatresult list (which will become the groupClause) if not already present
+ * there.  The sortClause is consulted for operator and sort order hints.
+ *
+ * Returns the ressortgroupref of the expression.
+ *
+ * flatresult	reference to flat list of SortGroupClause nodes
+ * seen_local	bitmapset of sortgrouprefs already seen at the local level
+ * pstate		ParseState
+ * gexpr		node to transform
+ * targetlist	reference to TargetEntry list
+ * sortClause	ORDER BY clause (SortGroupClause nodes)
+ * exprKind		expression kind
+ * useSQL99		SQL99 rather than SQL92 syntax
+ * toplevel		false if within any grouping set
+ */
+static Index
+transformGroupClauseExpr(List **flatresult, Bitmapset *seen_local,
+						 ParseState *pstate, Node *gexpr,
+						 List **targetlist, List *sortClause,
+						 ParseExprKind exprKind, bool useSQL99, bool toplevel)
+{
+	TargetEntry *tle;
+	bool		found = false;
+
+	if (useSQL99)
+		tle = findTargetlistEntrySQL99(pstate, gexpr,
+									   targetlist, exprKind);
+	else
+		tle = findTargetlistEntrySQL92(pstate, gexpr,
+									   targetlist, exprKind);
+
+	if (tle->ressortgroupref > 0)
+	{
+		ListCell   *sl;
+
+		/*
+		 * Eliminate duplicates (GROUP BY x, x) but only at local level.
+		 * (Duplicates in grouping sets can affect the number of returned
+		 * rows, so can't be dropped indiscriminately.)
+		 *
+		 * Since we don't care about anything except the sortgroupref, we can
+		 * use a bitmapset rather than scanning lists.
+		 */
+		if (bms_is_member(tle->ressortgroupref, seen_local))
+			return 0;
+
+		/*
+		 * If we're already in the flat clause list, we don't need to consider
+		 * adding ourselves again.
+		 */
+		found = targetIsInSortList(tle, InvalidOid, *flatresult);
+		if (found)
+			return tle->ressortgroupref;
+
+		/*
+		 * If the GROUP BY tlist entry also appears in ORDER BY, copy operator
+		 * info from the (first) matching ORDER BY item.  This means that if
+		 * you write something like "GROUP BY foo ORDER BY foo USING <<<", the
+		 * GROUP BY operation silently takes on the equality semantics implied
+		 * by the ORDER BY.  There are two reasons to do this: it improves the
+		 * odds that we can implement both GROUP BY and ORDER BY with a single
+		 * sort step, and it allows the user to choose the equality semantics
+		 * used by GROUP BY, should she be working with a datatype that has
+		 * more than one equality operator.
+		 *
+		 * If we're in a grouping set, though, we force our requested ordering
+		 * to be NULLS LAST, because if we have any hope of using a sorted agg
+		 * for the job, we're going to be tacking on generated NULL values
+		 * after the corresponding groups. If the user demands nulls first,
+		 * another sort step is going to be inevitable, but that's the
+		 * planner's problem.
+		 */
+
+		foreach(sl, sortClause)
+		{
+			SortGroupClause *sc = (SortGroupClause *) lfirst(sl);
+
+			if (sc->tleSortGroupRef == tle->ressortgroupref)
+			{
+				SortGroupClause *grpc = copyObject(sc);
+
+				if (!toplevel)
+					grpc->nulls_first = false;
+				*flatresult = lappend(*flatresult, grpc);
+				found = true;
+				break;
+			}
+		}
+	}
+
+	/*
+	 * If no match in ORDER BY, just add it to the result using default
+	 * sort/group semantics.
+	 */
+	if (!found)
+		*flatresult = addTargetToGroupList(pstate, tle,
+										   *flatresult, *targetlist,
+										   exprLocation(gexpr));
+
+	/*
+	 * _something_ must have assigned us a sortgroupref by now...
+	 */
+
+	return tle->ressortgroupref;
+}
+
+/*
+ * Transform a list of expressions within a GROUP BY clause or grouping set.
+ *
+ * The list of expressions belongs to a single clause within which duplicates
+ * can be safely eliminated.
+ *
+ * Returns an integer list of ressortgroupref values.
+ *
+ * flatresult	reference to flat list of SortGroupClause nodes
+ * pstate		ParseState
+ * list			nodes to transform
+ * targetlist	reference to TargetEntry list
+ * sortClause	ORDER BY clause (SortGroupClause nodes)
+ * exprKind		expression kind
+ * useSQL99		SQL99 rather than SQL92 syntax
+ * toplevel		false if within any grouping set
+ */
+static List *
+transformGroupClauseList(List **flatresult,
+						 ParseState *pstate, List *list,
+						 List **targetlist, List *sortClause,
+						 ParseExprKind exprKind, bool useSQL99, bool toplevel)
+{
+	Bitmapset  *seen_local = NULL;
+	List	   *result = NIL;
+	ListCell   *gl;
+
+	foreach(gl, list)
+	{
+		Node	   *gexpr = (Node *) lfirst(gl);
+
+		Index		ref = transformGroupClauseExpr(flatresult,
+												   seen_local,
+												   pstate,
+												   gexpr,
+												   targetlist,
+												   sortClause,
+												   exprKind,
+												   useSQL99,
+												   toplevel);
+
+		if (ref > 0)
+		{
+			seen_local = bms_add_member(seen_local, ref);
+			result = lappend_int(result, ref);
+		}
+	}
+
+	return result;
+}
+
+/*
+ * Transform a grouping set and (recursively) its content.
+ *
+ * The grouping set might be a GROUPING SETS node with other grouping sets
+ * inside it, but SETS within SETS have already been flattened out before
+ * reaching here.
+ *
+ * Returns the transformed node, which now contains SIMPLE nodes with lists
+ * of ressortgrouprefs rather than expressions.
+ *
+ * flatresult	reference to flat list of SortGroupClause nodes
+ * pstate		ParseState
+ * gset			grouping set to transform
+ * targetlist	reference to TargetEntry list
+ * sortClause	ORDER BY clause (SortGroupClause nodes)
+ * exprKind		expression kind
+ * useSQL99		SQL99 rather than SQL92 syntax
+ * toplevel		false if within any grouping set
+ */
+static Node *
+transformGroupingSet(List **flatresult,
+					 ParseState *pstate, GroupingSet *gset,
+					 List **targetlist, List *sortClause,
+					 ParseExprKind exprKind, bool useSQL99, bool toplevel)
+{
+	ListCell   *gl;
+	List	   *content = NIL;
+
+	Assert(toplevel || gset->kind != GROUPING_SET_SETS);
+
+	foreach(gl, gset->content)
+	{
+		Node	   *n = lfirst(gl);
+
+		if (IsA(n, List))
+		{
+			List	   *l = transformGroupClauseList(flatresult,
+													 pstate, (List *) n,
+													 targetlist, sortClause,
+													 exprKind, useSQL99, false);
+
+			content = lappend(content, makeGroupingSet(GROUPING_SET_SIMPLE,
+													   l,
+													   exprLocation(n)));
+		}
+		else if (IsA(n, GroupingSet))
+		{
+			GroupingSet *gset2 = (GroupingSet *) lfirst(gl);
+
+			content = lappend(content, transformGroupingSet(flatresult,
+															pstate, gset2,
+															targetlist, sortClause,
+															exprKind, useSQL99, false));
+		}
+		else
+		{
+			Index		ref = transformGroupClauseExpr(flatresult,
+													   NULL,
+													   pstate,
+													   n,
+													   targetlist,
+													   sortClause,
+													   exprKind,
+													   useSQL99,
+													   false);
+
+			content = lappend(content, makeGroupingSet(GROUPING_SET_SIMPLE,
+													   list_make1_int(ref),
+													   exprLocation(n)));
+		}
+	}
+
+	/* Arbitrarily cap the size of CUBE, which has exponential growth */
+	if (gset->kind == GROUPING_SET_CUBE)
+	{
+		if (list_length(content) > 12)
+			ereport(ERROR,
+					(errcode(ERRCODE_TOO_MANY_COLUMNS),
+					 errmsg("CUBE is limited to 12 elements"),
+					 parser_errposition(pstate, gset->location)));
+	}
+
+	return (Node *) makeGroupingSet(gset->kind, content, gset->location);
+}
+
+
+/*
+ * transformGroupClause -
+ *	  transform a GROUP BY clause
+ *
+ * GROUP BY items will be added to the targetlist (as resjunk columns)
+ * if not already present, so the targetlist must be passed by reference.
+ *
+ * This is also used for window PARTITION BY clauses (which act almost the
+ * same, but are always interpreted per SQL99 rules).
+ *
+ * Grouping sets make this a lot more complex than it was. Our goal here is
+ * twofold: we make a flat list of SortGroupClause nodes referencing each
+ * distinct expression used for grouping, with those expressions added to the
+ * targetlist if needed. At the same time, we build the groupingSets tree,
+ * which stores only ressortgrouprefs as integer lists inside GroupingSet nodes
+ * (possibly nested, but limited in depth: a GROUPING_SET_SETS node can contain
+ * nested SIMPLE, CUBE or ROLLUP nodes, but not more sets - we flatten that
+ * out; while CUBE and ROLLUP can contain only SIMPLE nodes).
+ *
+ * We skip much of the hard work if there are no grouping sets.
+ *
+ * One subtlety is that the groupClause list can end up empty while the
+ * groupingSets list is not; this happens if there are only empty grouping
+ * sets, or an explicit GROUP BY (). This has the same effect as specifying
+ * aggregates or a HAVING clause with no GROUP BY; the output is one row per
+ * grouping set even if the input is empty.
+ *
+ * Returns the transformed (flat) groupClause.
+ *
+ * pstate		ParseState
+ * grouplist	clause to transform
+ * groupingSets reference to list to contain the grouping set tree
+ * targetlist	reference to TargetEntry list
+ * sortClause	ORDER BY clause (SortGroupClause nodes)
+ * exprKind		expression kind
+ * useSQL99		SQL99 rather than SQL92 syntax
+ */
+List *
+transformGroupClause(ParseState *pstate, List *grouplist, List **groupingSets,
+					 List **targetlist, List *sortClause,
+					 ParseExprKind exprKind, bool useSQL99)
+{
+	List	   *result = NIL;
+	List	   *flat_grouplist;
+	List	   *gsets = NIL;
+	ListCell   *gl;
+	bool		hasGroupingSets = false;
+	Bitmapset  *seen_local = NULL;
+
+	/*
+	 * Recursively flatten implicit RowExprs. (Technically this is only needed
+	 * for GROUP BY, per the syntax rules for grouping sets, but we do it
+	 * anyway.)
+	 */
+	flat_grouplist = (List *) flatten_grouping_sets((Node *) grouplist,
+													true,
+													&hasGroupingSets);
+
+	/*
+	 * If the list is now empty, but hasGroupingSets is true, it's because we
+	 * elided redundant empty grouping sets. Restore a single empty grouping
+	 * set to leave a canonical form: GROUP BY ()
+	 */
+
+	if (flat_grouplist == NIL && hasGroupingSets)
+	{
+		flat_grouplist = list_make1(makeGroupingSet(GROUPING_SET_EMPTY,
+													NIL,
+													exprLocation((Node *) grouplist)));
+	}
+
+	foreach(gl, flat_grouplist)
+	{
+		Node	   *gexpr = (Node *) lfirst(gl);
+
+		if (IsA(gexpr, GroupingSet))
+		{
+			GroupingSet *gset = (GroupingSet *) gexpr;
+
+			switch (gset->kind)
+			{
+				case GROUPING_SET_EMPTY:
+					gsets = lappend(gsets, gset);
+					break;
+				case GROUPING_SET_SIMPLE:
+					/* can't happen */
+					Assert(false);
+					break;
+				case GROUPING_SET_SETS:
+				case GROUPING_SET_CUBE:
+				case GROUPING_SET_ROLLUP:
+					gsets = lappend(gsets,
+									transformGroupingSet(&result,
+														 pstate, gset,
+														 targetlist, sortClause,
+														 exprKind, useSQL99, true));
+					break;
+			}
+		}
+		else
+		{
+			Index		ref = transformGroupClauseExpr(&result, seen_local,
+													   pstate, gexpr,
+													   targetlist, sortClause,
+													   exprKind, useSQL99, true);
+
+			if (ref > 0)
+			{
+				seen_local = bms_add_member(seen_local, ref);
+				if (hasGroupingSets)
+					gsets = lappend(gsets,
+									makeGroupingSet(GROUPING_SET_SIMPLE,
+													list_make1_int(ref),
+													exprLocation(gexpr)));
+			}
+		}
+	}
+
+	/* parser should prevent this */
+	Assert(gsets == NIL || groupingSets != NULL);
+
+	if (groupingSets)
+		*groupingSets = gsets;
+
+	return result;
+}
+
+/*
+ * transformSortClause -
+ *	  transform an ORDER BY clause
+ *
+ * ORDER BY items will be added to the targetlist (as resjunk columns)
+ * if not already present, so the targetlist must be passed by reference.
+ *
+ * This is also used for window and aggregate ORDER BY clauses (which act
+ * almost the same, but are always interpreted per SQL99 rules).
+ */
+List *
+transformSortClause(ParseState *pstate,
+					List *orderlist,
+					List **targetlist,
+					ParseExprKind exprKind,
+					bool useSQL99)
+{
+	List	   *sortlist = NIL;
+	ListCell   *olitem;
+
+	foreach(olitem, orderlist)
+	{
+		SortBy	   *sortby = (SortBy *) lfirst(olitem);
+		TargetEntry *tle;
+
+		if (useSQL99)
+			tle = findTargetlistEntrySQL99(pstate, sortby->node,
+										   targetlist, exprKind);
+		else
+			tle = findTargetlistEntrySQL92(pstate, sortby->node,
+										   targetlist, exprKind);
+
+		sortlist = addTargetToSortList(pstate, tle,
+									   sortlist, *targetlist, sortby);
+	}
+
+	return sortlist;
+}
+
+/*
+ * transformWindowDefinitions -
+ *		transform window definitions (WindowDef to WindowClause)
+ */
+List *
+transformWindowDefinitions(ParseState *pstate,
+						   List *windowdefs,
+						   List **targetlist)
+{
+	List	   *result = NIL;
+	Index		winref = 0;
+	ListCell   *lc;
+
+	foreach(lc, windowdefs)
+	{
+		WindowDef  *windef = (WindowDef *) lfirst(lc);
+		WindowClause *refwc = NULL;
+		List	   *partitionClause;
+		List	   *orderClause;
+		Oid			rangeopfamily = InvalidOid;
+		Oid			rangeopcintype = InvalidOid;
+		WindowClause *wc;
+
+		winref++;
+
+		/*
+		 * Check for duplicate window names.
+		 */
+		if (windef->name &&
+			findWindowClause(result, windef->name) != NULL)
+			ereport(ERROR,
+					(errcode(ERRCODE_WINDOWING_ERROR),
+					 errmsg("window \"%s\" is already defined", windef->name),
+					 parser_errposition(pstate, windef->location)));
+
+		/*
+		 * If it references a previous window, look that up.
+		 */
+		if (windef->refname)
+		{
+			refwc = findWindowClause(result, windef->refname);
+			if (refwc == NULL)
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("window \"%s\" does not exist",
+								windef->refname),
+						 parser_errposition(pstate, windef->location)));
+		}
+
+		/*
+		 * Transform PARTITION and ORDER specs, if any.  These are treated
+		 * almost exactly like top-level GROUP BY and ORDER BY clauses,
+		 * including the special handling of nondefault operator semantics.
+		 */
+		orderClause = transformSortClause(pstate,
+										  windef->orderClause,
+										  targetlist,
+										  EXPR_KIND_WINDOW_ORDER,
+										  true /* force SQL99 rules */ );
+		partitionClause = transformGroupClause(pstate,
+											   windef->partitionClause,
+											   NULL,
+											   targetlist,
+											   orderClause,
+											   EXPR_KIND_WINDOW_PARTITION,
+											   true /* force SQL99 rules */ );
+
+		/*
+		 * And prepare the new WindowClause.
+		 */
+		wc = makeNode(WindowClause);
+		wc->name = windef->name;
+		wc->refname = windef->refname;
+
+		/*
+		 * Per spec, a windowdef that references a previous one copies the
+		 * previous partition clause (and mustn't specify its own).  It can
+		 * specify its own ordering clause, but only if the previous one had
+		 * none.  It always specifies its own frame clause, and the previous
+		 * one must not have a frame clause.  Yeah, it's bizarre that each of
+		 * these cases works differently, but SQL:2008 says so; see 7.11
+		 * <window clause> syntax rule 10 and general rule 1.  The frame
+		 * clause rule is especially bizarre because it makes "OVER foo"
+		 * different from "OVER (foo)", and requires the latter to throw an
+		 * error if foo has a nondefault frame clause.  Well, ours not to
+		 * reason why, but we do go out of our way to throw a useful error
+		 * message for such cases.
+		 */
+		if (refwc)
+		{
+			if (partitionClause)
+				ereport(ERROR,
+						(errcode(ERRCODE_WINDOWING_ERROR),
+						 errmsg("cannot override PARTITION BY clause of window \"%s\"",
+								windef->refname),
+						 parser_errposition(pstate, windef->location)));
+			wc->partitionClause = copyObject(refwc->partitionClause);
+		}
+		else
+			wc->partitionClause = partitionClause;
+		if (refwc)
+		{
+			if (orderClause && refwc->orderClause)
+				ereport(ERROR,
+						(errcode(ERRCODE_WINDOWING_ERROR),
+						 errmsg("cannot override ORDER BY clause of window \"%s\"",
+								windef->refname),
+						 parser_errposition(pstate, windef->location)));
+			if (orderClause)
+			{
+				wc->orderClause = orderClause;
+				wc->copiedOrder = false;
+			}
+			else
+			{
+				wc->orderClause = copyObject(refwc->orderClause);
+				wc->copiedOrder = true;
+			}
+		}
+		else
+		{
+			wc->orderClause = orderClause;
+			wc->copiedOrder = false;
+		}
+		if (refwc && refwc->frameOptions != FRAMEOPTION_DEFAULTS)
+		{
+			/*
+			 * Use this message if this is a WINDOW clause, or if it's an OVER
+			 * clause that includes ORDER BY or framing clauses.  (We already
+			 * rejected PARTITION BY above, so no need to check that.)
+			 */
+			if (windef->name ||
+				orderClause || windef->frameOptions != FRAMEOPTION_DEFAULTS)
+				ereport(ERROR,
+						(errcode(ERRCODE_WINDOWING_ERROR),
+						 errmsg("cannot copy window \"%s\" because it has a frame clause",
+								windef->refname),
+						 parser_errposition(pstate, windef->location)));
+			/* Else this clause is just OVER (foo), so say this: */
+			ereport(ERROR,
+					(errcode(ERRCODE_WINDOWING_ERROR),
+					 errmsg("cannot copy window \"%s\" because it has a frame clause",
+							windef->refname),
+					 errhint("Omit the parentheses in this OVER clause."),
+					 parser_errposition(pstate, windef->location)));
+		}
+		wc->frameOptions = windef->frameOptions;
+
+		/*
+		 * RANGE offset PRECEDING/FOLLOWING requires exactly one ORDER BY
+		 * column; check that and get its sort opfamily info.
+		 */
+		if ((wc->frameOptions & FRAMEOPTION_RANGE) &&
+			(wc->frameOptions & (FRAMEOPTION_START_OFFSET |
+								 FRAMEOPTION_END_OFFSET)))
+		{
+			SortGroupClause *sortcl;
+			Node	   *sortkey;
+			int16		rangestrategy;
+
+			if (list_length(wc->orderClause) != 1)
+				ereport(ERROR,
+						(errcode(ERRCODE_WINDOWING_ERROR),
+						 errmsg("RANGE with offset PRECEDING/FOLLOWING requires exactly one ORDER BY column"),
+						 parser_errposition(pstate, windef->location)));
+			sortcl = linitial_node(SortGroupClause, wc->orderClause);
+			sortkey = get_sortgroupclause_expr(sortcl, *targetlist);
+			/* Find the sort operator in pg_amop */
+			if (!get_ordering_op_properties(sortcl->sortop,
+											&rangeopfamily,
+											&rangeopcintype,
+											&rangestrategy))
+				elog(ERROR, "operator %u is not a valid ordering operator",
+					 sortcl->sortop);
+			/* Record properties of sort ordering */
+			wc->inRangeColl = exprCollation(sortkey);
+			wc->inRangeAsc = (rangestrategy == BTLessStrategyNumber);
+			wc->inRangeNullsFirst = sortcl->nulls_first;
+		}
+
+		/* Per spec, GROUPS mode requires an ORDER BY clause */
+		if (wc->frameOptions & FRAMEOPTION_GROUPS)
+		{
+			if (wc->orderClause == NIL)
+				ereport(ERROR,
+						(errcode(ERRCODE_WINDOWING_ERROR),
+						 errmsg("GROUPS mode requires an ORDER BY clause"),
+						 parser_errposition(pstate, windef->location)));
+		}
+
+		/* Process frame offset expressions */
+		wc->startOffset = transformFrameOffset(pstate, wc->frameOptions,
+											   rangeopfamily, rangeopcintype,
+											   &wc->startInRangeFunc,
+											   windef->startOffset);
+		wc->endOffset = transformFrameOffset(pstate, wc->frameOptions,
+											 rangeopfamily, rangeopcintype,
+											 &wc->endInRangeFunc,
+											 windef->endOffset);
+		wc->runCondition = NIL;
+		wc->winref = winref;
+
+		result = lappend(result, wc);
+	}
+
+	return result;
+}
+
+/*
+ * transformDistinctClause -
+ *	  transform a DISTINCT clause
+ *
+ * Since we may need to add items to the query's targetlist, that list
+ * is passed by reference.
+ *
+ * As with GROUP BY, we absorb the sorting semantics of ORDER BY as much as
+ * possible into the distinctClause.  This avoids a possible need to re-sort,
+ * and allows the user to choose the equality semantics used by DISTINCT,
+ * should she be working with a datatype that has more than one equality
+ * operator.
+ *
+ * is_agg is true if we are transforming an aggregate(DISTINCT ...)
+ * function call.  This does not affect any behavior, only the phrasing
+ * of error messages.
+ */
+List *
+transformDistinctClause(ParseState *pstate,
+						List **targetlist, List *sortClause, bool is_agg)
+{
+	List	   *result = NIL;
+	ListCell   *slitem;
+	ListCell   *tlitem;
+
+	/*
+	 * The distinctClause should consist of all ORDER BY items followed by all
+	 * other non-resjunk targetlist items.  There must not be any resjunk
+	 * ORDER BY items --- that would imply that we are sorting by a value that
+	 * isn't necessarily unique within a DISTINCT group, so the results
+	 * wouldn't be well-defined.  This construction ensures we follow the rule
+	 * that sortClause and distinctClause match; in fact the sortClause will
+	 * always be a prefix of distinctClause.
+	 *
+	 * Note a corner case: the same TLE could be in the ORDER BY list multiple
+	 * times with different sortops.  We have to include it in the
+	 * distinctClause the same way to preserve the prefix property. The net
+	 * effect will be that the TLE value will be made unique according to both
+	 * sortops.
+	 */
+	foreach(slitem, sortClause)
+	{
+		SortGroupClause *scl = (SortGroupClause *) lfirst(slitem);
+		TargetEntry *tle = get_sortgroupclause_tle(scl, *targetlist);
+
+		if (tle->resjunk)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
+					 is_agg ?
+					 errmsg("in an aggregate with DISTINCT, ORDER BY expressions must appear in argument list") :
+					 errmsg("for SELECT DISTINCT, ORDER BY expressions must appear in select list"),
+					 parser_errposition(pstate,
+										exprLocation((Node *) tle->expr))));
+		result = lappend(result, copyObject(scl));
+	}
+
+	/*
+	 * Now add any remaining non-resjunk tlist items, using default sort/group
+	 * semantics for their data types.
+	 */
+	foreach(tlitem, *targetlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(tlitem);
+
+		if (tle->resjunk)
+			continue;			/* ignore junk */
+		result = addTargetToGroupList(pstate, tle,
+									  result, *targetlist,
+									  exprLocation((Node *) tle->expr));
+	}
+
+	/*
+	 * Complain if we found nothing to make DISTINCT.  Returning an empty list
+	 * would cause the parsed Query to look like it didn't have DISTINCT, with
+	 * results that would probably surprise the user.  Note: this case is
+	 * presently impossible for aggregates because of grammar restrictions,
+	 * but we check anyway.
+	 */
+	if (result == NIL)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 is_agg ?
+				 errmsg("an aggregate with DISTINCT must have at least one argument") :
+				 errmsg("SELECT DISTINCT must have at least one column")));
+
+	return result;
+}
+
+/*
+ * transformDistinctOnClause -
+ *	  transform a DISTINCT ON clause
+ *
+ * Since we may need to add items to the query's targetlist, that list
+ * is passed by reference.
+ *
+ * As with GROUP BY, we absorb the sorting semantics of ORDER BY as much as
+ * possible into the distinctClause.  This avoids a possible need to re-sort,
+ * and allows the user to choose the equality semantics used by DISTINCT,
+ * should she be working with a datatype that has more than one equality
+ * operator.
+ */
+List *
+transformDistinctOnClause(ParseState *pstate, List *distinctlist,
+						  List **targetlist, List *sortClause)
+{
+	List	   *result = NIL;
+	List	   *sortgrouprefs = NIL;
+	bool		skipped_sortitem;
+	ListCell   *lc;
+	ListCell   *lc2;
+
+	/*
+	 * Add all the DISTINCT ON expressions to the tlist (if not already
+	 * present, they are added as resjunk items).  Assign sortgroupref numbers
+	 * to them, and make a list of these numbers.  (NB: we rely below on the
+	 * sortgrouprefs list being one-for-one with the original distinctlist.
+	 * Also notice that we could have duplicate DISTINCT ON expressions and
+	 * hence duplicate entries in sortgrouprefs.)
+	 */
+	foreach(lc, distinctlist)
+	{
+		Node	   *dexpr = (Node *) lfirst(lc);
+		int			sortgroupref;
+		TargetEntry *tle;
+
+		tle = findTargetlistEntrySQL92(pstate, dexpr, targetlist,
+									   EXPR_KIND_DISTINCT_ON);
+		sortgroupref = assignSortGroupRef(tle, *targetlist);
+		sortgrouprefs = lappend_int(sortgrouprefs, sortgroupref);
+	}
+
+	/*
+	 * If the user writes both DISTINCT ON and ORDER BY, adopt the sorting
+	 * semantics from ORDER BY items that match DISTINCT ON items, and also
+	 * adopt their column sort order.  We insist that the distinctClause and
+	 * sortClause match, so throw error if we find the need to add any more
+	 * distinctClause items after we've skipped an ORDER BY item that wasn't
+	 * in DISTINCT ON.
+	 */
+	skipped_sortitem = false;
+	foreach(lc, sortClause)
+	{
+		SortGroupClause *scl = (SortGroupClause *) lfirst(lc);
+
+		if (list_member_int(sortgrouprefs, scl->tleSortGroupRef))
+		{
+			if (skipped_sortitem)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
+						 errmsg("SELECT DISTINCT ON expressions must match initial ORDER BY expressions"),
+						 parser_errposition(pstate,
+											get_matching_location(scl->tleSortGroupRef,
+																  sortgrouprefs,
+																  distinctlist))));
+			else
+				result = lappend(result, copyObject(scl));
+		}
+		else
+			skipped_sortitem = true;
+	}
+
+	/*
+	 * Now add any remaining DISTINCT ON items, using default sort/group
+	 * semantics for their data types.  (Note: this is pretty questionable; if
+	 * the ORDER BY list doesn't include all the DISTINCT ON items and more
+	 * besides, you certainly aren't using DISTINCT ON in the intended way,
+	 * and you probably aren't going to get consistent results.  It might be
+	 * better to throw an error or warning here.  But historically we've
+	 * allowed it, so keep doing so.)
+	 */
+	forboth(lc, distinctlist, lc2, sortgrouprefs)
+	{
+		Node	   *dexpr = (Node *) lfirst(lc);
+		int			sortgroupref = lfirst_int(lc2);
+		TargetEntry *tle = get_sortgroupref_tle(sortgroupref, *targetlist);
+
+		if (targetIsInSortList(tle, InvalidOid, result))
+			continue;			/* already in list (with some semantics) */
+		if (skipped_sortitem)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
+					 errmsg("SELECT DISTINCT ON expressions must match initial ORDER BY expressions"),
+					 parser_errposition(pstate, exprLocation(dexpr))));
+		result = addTargetToGroupList(pstate, tle,
+									  result, *targetlist,
+									  exprLocation(dexpr));
+	}
+
+	/*
+	 * An empty result list is impossible here because of grammar
+	 * restrictions.
+	 */
+	Assert(result != NIL);
+
+	return result;
+}
+
+/*
+ * get_matching_location
+ *		Get the exprLocation of the exprs member corresponding to the
+ *		(first) member of sortgrouprefs that equals sortgroupref.
+ *
+ * This is used so that we can point at a troublesome DISTINCT ON entry.
+ * (Note that we need to use the original untransformed DISTINCT ON list
+ * item, as whatever TLE it corresponds to will very possibly have a
+ * parse location pointing to some matching entry in the SELECT list
+ * or ORDER BY list.)
+ */
+static int
+get_matching_location(int sortgroupref, List *sortgrouprefs, List *exprs)
+{
+	ListCell   *lcs;
+	ListCell   *lce;
+
+	forboth(lcs, sortgrouprefs, lce, exprs)
+	{
+		if (lfirst_int(lcs) == sortgroupref)
+			return exprLocation((Node *) lfirst(lce));
+	}
+	/* if no match, caller blew it */
+	elog(ERROR, "get_matching_location: no matching sortgroupref");
+	return -1;					/* keep compiler quiet */
+}
+
+/*
+ * resolve_unique_index_expr
+ *		Infer a unique index from a list of indexElems, for ON
+ *		CONFLICT clause
+ *
+ * Perform parse analysis of expressions and columns appearing within ON
+ * CONFLICT clause.  During planning, the returned list of expressions is used
+ * to infer which unique index to use.
+ */
+static List *
+resolve_unique_index_expr(ParseState *pstate, InferClause *infer,
+						  Relation heapRel)
+{
+	List	   *result = NIL;
+	ListCell   *l;
+
+	foreach(l, infer->indexElems)
+	{
+		IndexElem  *ielem = (IndexElem *) lfirst(l);
+		InferenceElem *pInfer = makeNode(InferenceElem);
+		Node	   *parse;
+
+		/*
+		 * Raw grammar re-uses CREATE INDEX infrastructure for unique index
+		 * inference clause, and so will accept opclasses by name and so on.
+		 *
+		 * Make no attempt to match ASC or DESC ordering or NULLS FIRST/NULLS
+		 * LAST ordering, since those are not significant for inference
+		 * purposes (any unique index matching the inference specification in
+		 * other regards is accepted indifferently).  Actively reject this as
+		 * wrong-headed.
+		 */
+		if (ielem->ordering != SORTBY_DEFAULT)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
+					 errmsg("ASC/DESC is not allowed in ON CONFLICT clause"),
+					 parser_errposition(pstate,
+										exprLocation((Node *) infer))));
+		if (ielem->nulls_ordering != SORTBY_NULLS_DEFAULT)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
+					 errmsg("NULLS FIRST/LAST is not allowed in ON CONFLICT clause"),
+					 parser_errposition(pstate,
+										exprLocation((Node *) infer))));
+
+		if (!ielem->expr)
+		{
+			/* Simple index attribute */
+			ColumnRef  *n;
+
+			/*
+			 * Grammar won't have built raw expression for us in event of
+			 * plain column reference.  Create one directly, and perform
+			 * expression transformation.  Planner expects this, and performs
+			 * its own normalization for the purposes of matching against
+			 * pg_index.
+			 */
+			n = makeNode(ColumnRef);
+			n->fields = list_make1(makeString(ielem->name));
+			/* Location is approximately that of inference specification */
+			n->location = infer->location;
+			parse = (Node *) n;
+		}
+		else
+		{
+			/* Do parse transformation of the raw expression */
+			parse = (Node *) ielem->expr;
+		}
+
+		/*
+		 * transformExpr() will reject subqueries, aggregates, window
+		 * functions, and SRFs, based on being passed
+		 * EXPR_KIND_INDEX_EXPRESSION.  So we needn't worry about those
+		 * further ... not that they would match any available index
+		 * expression anyway.
+		 */
+		pInfer->expr = transformExpr(pstate, parse, EXPR_KIND_INDEX_EXPRESSION);
+
+		/* Perform lookup of collation and operator class as required */
+		if (!ielem->collation)
+			pInfer->infercollid = InvalidOid;
+		else
+			pInfer->infercollid = LookupCollation(pstate, ielem->collation,
+												  exprLocation(pInfer->expr));
+
+		if (!ielem->opclass)
+			pInfer->inferopclass = InvalidOid;
+		else
+			pInfer->inferopclass = get_opclass_oid(BTREE_AM_OID,
+												   ielem->opclass, false);
+
+		result = lappend(result, pInfer);
+	}
+
+	return result;
+}
+
+/*
+ * transformOnConflictArbiter -
+ *		transform arbiter expressions in an ON CONFLICT clause.
+ *
+ * Transformed expressions used to infer one unique index relation to serve as
+ * an ON CONFLICT arbiter.  Partial unique indexes may be inferred using WHERE
+ * clause from inference specification clause.
+ */
+void
+transformOnConflictArbiter(ParseState *pstate,
+						   OnConflictClause *onConflictClause,
+						   List **arbiterExpr, Node **arbiterWhere,
+						   Oid *constraint)
+{
+	InferClause *infer = onConflictClause->infer;
+
+	*arbiterExpr = NIL;
+	*arbiterWhere = NULL;
+	*constraint = InvalidOid;
+
+	if (onConflictClause->action == ONCONFLICT_UPDATE && !infer)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("ON CONFLICT DO UPDATE requires inference specification or constraint name"),
+				 errhint("For example, ON CONFLICT (column_name)."),
+				 parser_errposition(pstate,
+									exprLocation((Node *) onConflictClause))));
+
+	/*
+	 * To simplify certain aspects of its design, speculative insertion into
+	 * system catalogs is disallowed
+	 */
+	if (IsCatalogRelation(pstate->p_target_relation))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("ON CONFLICT is not supported with system catalog tables"),
+				 parser_errposition(pstate,
+									exprLocation((Node *) onConflictClause))));
+
+	/* Same applies to table used by logical decoding as catalog table */
+	if (RelationIsUsedAsCatalogTable(pstate->p_target_relation))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("ON CONFLICT is not supported on table \"%s\" used as a catalog table",
+						RelationGetRelationName(pstate->p_target_relation)),
+				 parser_errposition(pstate,
+									exprLocation((Node *) onConflictClause))));
+
+	/* ON CONFLICT DO NOTHING does not require an inference clause */
+	if (infer)
+	{
+		if (infer->indexElems)
+			*arbiterExpr = resolve_unique_index_expr(pstate, infer,
+													 pstate->p_target_relation);
+
+		/*
+		 * Handling inference WHERE clause (for partial unique index
+		 * inference)
+		 */
+		if (infer->whereClause)
+			*arbiterWhere = transformExpr(pstate, infer->whereClause,
+										  EXPR_KIND_INDEX_PREDICATE);
+
+		/*
+		 * If the arbiter is specified by constraint name, get the constraint
+		 * OID and mark the constrained columns as requiring SELECT privilege,
+		 * in the same way as would have happened if the arbiter had been
+		 * specified by explicit reference to the constraint's index columns.
+		 */
+		if (infer->conname)
+		{
+			Oid			relid = RelationGetRelid(pstate->p_target_relation);
+			RangeTblEntry *rte = pstate->p_target_nsitem->p_rte;
+			Bitmapset  *conattnos;
+
+			conattnos = get_relation_constraint_attnos(relid, infer->conname,
+													   false, constraint);
+
+			/* Make sure the rel as a whole is marked for SELECT access */
+			rte->requiredPerms |= ACL_SELECT;
+			/* Mark the constrained columns as requiring SELECT access */
+			rte->selectedCols = bms_add_members(rte->selectedCols, conattnos);
+		}
+	}
+
+	/*
+	 * It's convenient to form a list of expressions based on the
+	 * representation used by CREATE INDEX, since the same restrictions are
+	 * appropriate (e.g. on subqueries).  However, from here on, a dedicated
+	 * primnode representation is used for inference elements, and so
+	 * assign_query_collations() can be trusted to do the right thing with the
+	 * post parse analysis query tree inference clause representation.
+	 */
+}
+
+/*
+ * addTargetToSortList
+ *		If the given targetlist entry isn't already in the SortGroupClause
+ *		list, add it to the end of the list, using the given sort ordering
+ *		info.
+ *
+ * Returns the updated SortGroupClause list.
+ */
+List *
+addTargetToSortList(ParseState *pstate, TargetEntry *tle,
+					List *sortlist, List *targetlist, SortBy *sortby)
+{
+	Oid			restype = exprType((Node *) tle->expr);
+	Oid			sortop;
+	Oid			eqop;
+	bool		hashable;
+	bool		reverse;
+	int			location;
+	ParseCallbackState pcbstate;
+
+	/* if tlist item is an UNKNOWN literal, change it to TEXT */
+	if (restype == UNKNOWNOID)
+	{
+		tle->expr = (Expr *) coerce_type(pstate, (Node *) tle->expr,
+										 restype, TEXTOID, -1,
+										 COERCION_IMPLICIT,
+										 COERCE_IMPLICIT_CAST,
+										 -1);
+		restype = TEXTOID;
+	}
+
+	/*
+	 * Rather than clutter the API of get_sort_group_operators and the other
+	 * functions we're about to use, make use of error context callback to
+	 * mark any error reports with a parse position.  We point to the operator
+	 * location if present, else to the expression being sorted.  (NB: use the
+	 * original untransformed expression here; the TLE entry might well point
+	 * at a duplicate expression in the regular SELECT list.)
+	 */
+	location = sortby->location;
+	if (location < 0)
+		location = exprLocation(sortby->node);
+	setup_parser_errposition_callback(&pcbstate, pstate, location);
+
+	/* determine the sortop, eqop, and directionality */
+	switch (sortby->sortby_dir)
+	{
+		case SORTBY_DEFAULT:
+		case SORTBY_ASC:
+			get_sort_group_operators(restype,
+									 true, true, false,
+									 &sortop, &eqop, NULL,
+									 &hashable);
+			reverse = false;
+			break;
+		case SORTBY_DESC:
+			get_sort_group_operators(restype,
+									 false, true, true,
+									 NULL, &eqop, &sortop,
+									 &hashable);
+			reverse = true;
+			break;
+		case SORTBY_USING:
+			Assert(sortby->useOp != NIL);
+			sortop = compatible_oper_opid(sortby->useOp,
+										  restype,
+										  restype,
+										  false);
+
+			/*
+			 * Verify it's a valid ordering operator, fetch the corresponding
+			 * equality operator, and determine whether to consider it like
+			 * ASC or DESC.
+			 */
+			eqop = get_equality_op_for_ordering_op(sortop, &reverse);
+			if (!OidIsValid(eqop))
+				ereport(ERROR,
+						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+						 errmsg("operator %s is not a valid ordering operator",
+								strVal(llast(sortby->useOp))),
+						 errhint("Ordering operators must be \"<\" or \">\" members of btree operator families.")));
+
+			/*
+			 * Also see if the equality operator is hashable.
+			 */
+			hashable = op_hashjoinable(eqop, restype);
+			break;
+		default:
+			elog(ERROR, "unrecognized sortby_dir: %d", sortby->sortby_dir);
+			sortop = InvalidOid;	/* keep compiler quiet */
+			eqop = InvalidOid;
+			hashable = false;
+			reverse = false;
+			break;
+	}
+
+	cancel_parser_errposition_callback(&pcbstate);
+
+	/* avoid making duplicate sortlist entries */
+	if (!targetIsInSortList(tle, sortop, sortlist))
+	{
+		SortGroupClause *sortcl = makeNode(SortGroupClause);
+
+		sortcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist);
+
+		sortcl->eqop = eqop;
+		sortcl->sortop = sortop;
+		sortcl->hashable = hashable;
+
+		switch (sortby->sortby_nulls)
+		{
+			case SORTBY_NULLS_DEFAULT:
+				/* NULLS FIRST is default for DESC; other way for ASC */
+				sortcl->nulls_first = reverse;
+				break;
+			case SORTBY_NULLS_FIRST:
+				sortcl->nulls_first = true;
+				break;
+			case SORTBY_NULLS_LAST:
+				sortcl->nulls_first = false;
+				break;
+			default:
+				elog(ERROR, "unrecognized sortby_nulls: %d",
+					 sortby->sortby_nulls);
+				break;
+		}
+
+		sortlist = lappend(sortlist, sortcl);
+	}
+
+	return sortlist;
+}
+
+/*
+ * addTargetToGroupList
+ *		If the given targetlist entry isn't already in the SortGroupClause
+ *		list, add it to the end of the list, using default sort/group
+ *		semantics.
+ *
+ * This is very similar to addTargetToSortList, except that we allow the
+ * case where only a grouping (equality) operator can be found, and that
+ * the TLE is considered "already in the list" if it appears there with any
+ * sorting semantics.
+ *
+ * location is the parse location to be fingered in event of trouble.  Note
+ * that we can't rely on exprLocation(tle->expr), because that might point
+ * to a SELECT item that matches the GROUP BY item; it'd be pretty confusing
+ * to report such a location.
+ *
+ * Returns the updated SortGroupClause list.
+ */
+static List *
+addTargetToGroupList(ParseState *pstate, TargetEntry *tle,
+					 List *grouplist, List *targetlist, int location)
+{
+	Oid			restype = exprType((Node *) tle->expr);
+
+	/* if tlist item is an UNKNOWN literal, change it to TEXT */
+	if (restype == UNKNOWNOID)
+	{
+		tle->expr = (Expr *) coerce_type(pstate, (Node *) tle->expr,
+										 restype, TEXTOID, -1,
+										 COERCION_IMPLICIT,
+										 COERCE_IMPLICIT_CAST,
+										 -1);
+		restype = TEXTOID;
+	}
+
+	/* avoid making duplicate grouplist entries */
+	if (!targetIsInSortList(tle, InvalidOid, grouplist))
+	{
+		SortGroupClause *grpcl = makeNode(SortGroupClause);
+		Oid			sortop;
+		Oid			eqop;
+		bool		hashable;
+		ParseCallbackState pcbstate;
+
+		setup_parser_errposition_callback(&pcbstate, pstate, location);
+
+		/* determine the eqop and optional sortop */
+		get_sort_group_operators(restype,
+								 false, true, false,
+								 &sortop, &eqop, NULL,
+								 &hashable);
+
+		cancel_parser_errposition_callback(&pcbstate);
+
+		grpcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist);
+		grpcl->eqop = eqop;
+		grpcl->sortop = sortop;
+		grpcl->nulls_first = false; /* OK with or without sortop */
+		grpcl->hashable = hashable;
+
+		grouplist = lappend(grouplist, grpcl);
+	}
+
+	return grouplist;
+}
+
+/*
+ * assignSortGroupRef
+ *	  Assign the targetentry an unused ressortgroupref, if it doesn't
+ *	  already have one.  Return the assigned or pre-existing refnumber.
+ *
+ * 'tlist' is the targetlist containing (or to contain) the given targetentry.
+ */
+Index
+assignSortGroupRef(TargetEntry *tle, List *tlist)
+{
+	Index		maxRef;
+	ListCell   *l;
+
+	if (tle->ressortgroupref)	/* already has one? */
+		return tle->ressortgroupref;
+
+	/* easiest way to pick an unused refnumber: max used + 1 */
+	maxRef = 0;
+	foreach(l, tlist)
+	{
+		Index		ref = ((TargetEntry *) lfirst(l))->ressortgroupref;
+
+		if (ref > maxRef)
+			maxRef = ref;
+	}
+	tle->ressortgroupref = maxRef + 1;
+	return tle->ressortgroupref;
+}
+
+/*
+ * targetIsInSortList
+ *		Is the given target item already in the sortlist?
+ *		If sortop is not InvalidOid, also test for a match to the sortop.
+ *
+ * It is not an oversight that this function ignores the nulls_first flag.
+ * We check sortop when determining if an ORDER BY item is redundant with
+ * earlier ORDER BY items, because it's conceivable that "ORDER BY
+ * foo USING <, foo USING <<<" is not redundant, if <<< distinguishes
+ * values that < considers equal.  We need not check nulls_first
+ * however, because a lower-order column with the same sortop but
+ * opposite nulls direction is redundant.  Also, we can consider
+ * ORDER BY foo ASC, foo DESC redundant, so check for a commutator match.
+ *
+ * Works for both ordering and grouping lists (sortop would normally be
+ * InvalidOid when considering grouping).  Note that the main reason we need
+ * this routine (and not just a quick test for nonzeroness of ressortgroupref)
+ * is that a TLE might be in only one of the lists.
+ */
+bool
+targetIsInSortList(TargetEntry *tle, Oid sortop, List *sortList)
+{
+	Index		ref = tle->ressortgroupref;
+	ListCell   *l;
+
+	/* no need to scan list if tle has no marker */
+	if (ref == 0)
+		return false;
+
+	foreach(l, sortList)
+	{
+		SortGroupClause *scl = (SortGroupClause *) lfirst(l);
+
+		if (scl->tleSortGroupRef == ref &&
+			(sortop == InvalidOid ||
+			 sortop == scl->sortop ||
+			 sortop == get_commutator(scl->sortop)))
+			return true;
+	}
+	return false;
+}
+
+/*
+ * findWindowClause
+ *		Find the named WindowClause in the list, or return NULL if not there
+ */
+static WindowClause *
+findWindowClause(List *wclist, const char *name)
+{
+	ListCell   *l;
+
+	foreach(l, wclist)
+	{
+		WindowClause *wc = (WindowClause *) lfirst(l);
+
+		if (wc->name && strcmp(wc->name, name) == 0)
+			return wc;
+	}
+
+	return NULL;
+}
+
+/*
+ * transformFrameOffset
+ *		Process a window frame offset expression
+ *
+ * In RANGE mode, rangeopfamily is the sort opfamily for the input ORDER BY
+ * column, and rangeopcintype is the input data type the sort operator is
+ * registered with.  We expect the in_range function to be registered with
+ * that same type.  (In binary-compatible cases, it might be different from
+ * the input column's actual type, so we can't use that for the lookups.)
+ * We'll return the OID of the in_range function to *inRangeFunc.
+ */
+static Node *
+transformFrameOffset(ParseState *pstate, int frameOptions,
+					 Oid rangeopfamily, Oid rangeopcintype, Oid *inRangeFunc,
+					 Node *clause)
+{
+	const char *constructName = NULL;
+	Node	   *node;
+
+	*inRangeFunc = InvalidOid;	/* default result */
+
+	/* Quick exit if no offset expression */
+	if (clause == NULL)
+		return NULL;
+
+	if (frameOptions & FRAMEOPTION_ROWS)
+	{
+		/* Transform the raw expression tree */
+		node = transformExpr(pstate, clause, EXPR_KIND_WINDOW_FRAME_ROWS);
+
+		/*
+		 * Like LIMIT clause, simply coerce to int8
+		 */
+		constructName = "ROWS";
+		node = coerce_to_specific_type(pstate, node, INT8OID, constructName);
+	}
+	else if (frameOptions & FRAMEOPTION_RANGE)
+	{
+		/*
+		 * We must look up the in_range support function that's to be used,
+		 * possibly choosing one of several, and coerce the "offset" value to
+		 * the appropriate input type.
+		 */
+		Oid			nodeType;
+		Oid			preferredType;
+		int			nfuncs = 0;
+		int			nmatches = 0;
+		Oid			selectedType = InvalidOid;
+		Oid			selectedFunc = InvalidOid;
+		CatCList   *proclist;
+		int			i;
+
+		/* Transform the raw expression tree */
+		node = transformExpr(pstate, clause, EXPR_KIND_WINDOW_FRAME_RANGE);
+		nodeType = exprType(node);
+
+		/*
+		 * If there are multiple candidates, we'll prefer the one that exactly
+		 * matches nodeType; or if nodeType is as yet unknown, prefer the one
+		 * that exactly matches the sort column type.  (The second rule is
+		 * like what we do for "known_type operator unknown".)
+		 */
+		preferredType = (nodeType != UNKNOWNOID) ? nodeType : rangeopcintype;
+
+		/* Find the in_range support functions applicable to this case */
+		proclist = SearchSysCacheList2(AMPROCNUM,
+									   ObjectIdGetDatum(rangeopfamily),
+									   ObjectIdGetDatum(rangeopcintype));
+		for (i = 0; i < proclist->n_members; i++)
+		{
+			HeapTuple	proctup = &proclist->members[i]->tuple;
+			Form_pg_amproc procform = (Form_pg_amproc) GETSTRUCT(proctup);
+
+			/* The search will find all support proc types; ignore others */
+			if (procform->amprocnum != BTINRANGE_PROC)
+				continue;
+			nfuncs++;
+
+			/* Ignore function if given value can't be coerced to that type */
+			if (!can_coerce_type(1, &nodeType, &procform->amprocrighttype,
+								 COERCION_IMPLICIT))
+				continue;
+			nmatches++;
+
+			/* Remember preferred match, or any match if didn't find that */
+			if (selectedType != preferredType)
+			{
+				selectedType = procform->amprocrighttype;
+				selectedFunc = procform->amproc;
+			}
+		}
+		ReleaseCatCacheList(proclist);
+
+		/*
+		 * Throw error if needed.  It seems worth taking the trouble to
+		 * distinguish "no support at all" from "you didn't match any
+		 * available offset type".
+		 */
+		if (nfuncs == 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("RANGE with offset PRECEDING/FOLLOWING is not supported for column type %s",
+							format_type_be(rangeopcintype)),
+					 parser_errposition(pstate, exprLocation(node))));
+		if (nmatches == 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("RANGE with offset PRECEDING/FOLLOWING is not supported for column type %s and offset type %s",
+							format_type_be(rangeopcintype),
+							format_type_be(nodeType)),
+					 errhint("Cast the offset value to an appropriate type."),
+					 parser_errposition(pstate, exprLocation(node))));
+		if (nmatches != 1 && selectedType != preferredType)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("RANGE with offset PRECEDING/FOLLOWING has multiple interpretations for column type %s and offset type %s",
+							format_type_be(rangeopcintype),
+							format_type_be(nodeType)),
+					 errhint("Cast the offset value to the exact intended type."),
+					 parser_errposition(pstate, exprLocation(node))));
+
+		/* OK, coerce the offset to the right type */
+		constructName = "RANGE";
+		node = coerce_to_specific_type(pstate, node,
+									   selectedType, constructName);
+		*inRangeFunc = selectedFunc;
+	}
+	else if (frameOptions & FRAMEOPTION_GROUPS)
+	{
+		/* Transform the raw expression tree */
+		node = transformExpr(pstate, clause, EXPR_KIND_WINDOW_FRAME_GROUPS);
+
+		/*
+		 * Like LIMIT clause, simply coerce to int8
+		 */
+		constructName = "GROUPS";
+		node = coerce_to_specific_type(pstate, node, INT8OID, constructName);
+	}
+	else
+	{
+		Assert(false);
+		node = NULL;
+	}
+
+	/* Disallow variables in frame offsets */
+	checkExprIsVarFree(pstate, node, constructName);
+
+	return node;
+}