Get rid of long-since-vestigial Iter node type, in favor of adding a

returns-set boolean field in Func and Oper nodes.  This allows cleaner,
more reliable tests for expressions returning sets in the planner and
parser.  For example, a WHERE clause returning a set is now detected
and complained of in the parser, not only at runtime.

src/backend/catalog/heap.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.198 2002/05/03 04:11:08 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.199 2002/05/12 23:43:02 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -49,6 +49,7 @@
 #include "optimizer/planmain.h"
 #include "optimizer/prep.h"
 #include "optimizer/var.h"
+#include "parser/parse_coerce.h"
 #include "parser/parse_expr.h"
 #include "parser/parse_relation.h"
 #include "parser/parse_target.h"
@@ -1626,9 +1627,7 @@ AddRelationRawConstraints(Relation rel,
 		/*
 		 * Make sure it yields a boolean result.
 		 */
-		if (exprType(expr) != BOOLOID)
-			elog(ERROR, "CHECK constraint expression '%s' does not yield boolean result",
-				 ccname);
+		expr = coerce_to_boolean(expr, "CHECK");
 
 		/*
 		 * Make sure no outside relations are referred to.
@@ -1764,6 +1763,12 @@ cookDefault(ParseState *pstate,
 	if (contain_var_clause(expr))
 		elog(ERROR, "cannot use column references in DEFAULT clause");
 
+	/*
+	 * It can't return a set either.
+	 */
+	if (expression_returns_set(expr))
+		elog(ERROR, "DEFAULT clause must not return a set");
+
 	/*
 	 * No subplans or aggregates, either...
 	 */

src/backend/commands/tablecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.12 2002/04/27 21:24:34 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.13 2002/05/12 23:43:02 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -37,6 +37,7 @@
 #include "optimizer/planmain.h"
 #include "optimizer/prep.h"
 #include "parser/parse.h"
+#include "parser/parse_coerce.h"
 #include "parser/parse_expr.h"
 #include "parser/parse_relation.h"
 #include "parser/parse_type.h"
@@ -2461,9 +2462,7 @@ AlterTableAddConstraint(Oid myrelid,
 								/*
 								 * Make sure it yields a boolean result.
 								 */
-								if (exprType(expr) != BOOLOID)
-									elog(ERROR, "CHECK '%s' does not yield boolean result",
-										 name);
+								expr = coerce_to_boolean(expr, "CHECK");
 
 								/*
 								 * Make sure no outside relations are
@@ -2473,6 +2472,14 @@ AlterTableAddConstraint(Oid myrelid,
 									elog(ERROR, "Only relation '%s' can be referenced in CHECK",
 										 RelationGetRelationName(rel));
 
+								/*
+								 * No subplans or aggregates, either...
+								 */
+								if (contain_subplans(expr))
+									elog(ERROR, "cannot use subselect in CHECK constraint expression");
+								if (contain_agg_clause(expr))
+									elog(ERROR, "cannot use aggregate function in CHECK constraint expression");
+
 								/*
 								 * Might as well try to reduce any
 								 * constant expressions.

src/backend/executor/Makefile

@@ -4,7 +4,7 @@
 #    Makefile for executor
 #
 # IDENTIFICATION
-#    $Header: /cvsroot/pgsql/src/backend/executor/Makefile,v 1.18 2002/05/12 20:10:02 tgl Exp $
+#    $Header: /cvsroot/pgsql/src/backend/executor/Makefile,v 1.19 2002/05/12 23:43:02 tgl Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -12,7 +12,7 @@ subdir = src/backend/executor
 top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = execAmi.o execFlatten.o execJunk.o execMain.o \
+OBJS = execAmi.o execJunk.o execMain.o \
        execProcnode.o execQual.o execScan.o execTuples.o \
        execUtils.o functions.o instrument.o nodeAppend.o nodeAgg.o nodeHash.o \
        nodeHashjoin.o nodeIndexscan.o nodeMaterial.o nodeMergejoin.o \

src/backend/executor/execFlatten.c

-/*-------------------------------------------------------------------------
- *
- * execFlatten.c
- *	  This file handles the nodes associated with flattening sets in the
- *	  target list of queries containing functions returning sets.
- *
- * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- *
- * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/Attic/execFlatten.c,v 1.16 2001/10/28 06:25:43 momjian Exp $
- *
- *-------------------------------------------------------------------------
- */
-
-/*
- * ExecEvalIter() -
- *	 Iterate through the all return tuples/base types from a function one
- *	 at time (i.e. one per ExecEvalIter call).	Not really needed for
- *	 postquel functions, but for reasons of orthogonality, these nodes
- *	 exist above pq functions as well as c functions.
- *
- * ExecEvalFjoin() -
- *	 Given N Iter nodes return a vector of all combinations of results
- *	 one at a time (i.e. one result vector per ExecEvalFjoin call).  This
- *	 node does the actual flattening work.
- */
-#include "postgres.h"
-#include "executor/execFlatten.h"
-#include "executor/executor.h"
-
-#ifdef SETS_FIXED
-static bool FjoinBumpOuterNodes(TargetEntry *tlist, ExprContext *econtext,
-					DatumPtr results, char *nulls);
-#endif
-
-
-Datum
-ExecEvalIter(Iter *iterNode,
-			 ExprContext *econtext,
-			 bool *isNull,
-			 ExprDoneCond *isDone)
-{
-	Node	   *expression;
-
-	expression = iterNode->iterexpr;
-
-	/*
-	 * Really Iter nodes are only needed for C functions, postquel
-	 * function by their nature return 1 result at a time.	For now we are
-	 * only worrying about postquel functions, c functions will come
-	 * later.
-	 */
-	return ExecEvalExpr(expression, econtext, isNull, isDone);
-}
-
-void
-ExecEvalFjoin(TargetEntry *tlist,
-			  ExprContext *econtext,
-			  bool *isNullVect,
-			  ExprDoneCond *fj_isDone)
-{
-
-#ifdef SETS_FIXED
-	bool		isDone;
-	int			curNode;
-	List	   *tlistP;
-
-	Fjoin	   *fjNode = tlist->fjoin;
-	DatumPtr	resVect = fjNode->fj_results;
-	BoolPtr		alwaysDone = fjNode->fj_alwaysDone;
-
-	if (fj_isDone)
-		*fj_isDone = ExprMultipleResult;
-
-	/*
-	 * For the next tuple produced by the plan, we need to re-initialize
-	 * the Fjoin node.
-	 */
-	if (!fjNode->fj_initialized)
-	{
-		/*
-		 * Initialize all of the Outer nodes
-		 */
-		curNode = 1;
-		foreach(tlistP, lnext(tlist))
-		{
-			TargetEntry *tle = lfirst(tlistP);
-
-			resVect[curNode] = ExecEvalIter((Iter *) tle->expr,
-											econtext,
-											&isNullVect[curNode],
-											&isDone);
-			if (isDone)
-				isNullVect[curNode] = alwaysDone[curNode] = true;
-			else
-				alwaysDone[curNode] = false;
-
-			curNode++;
-		}
-
-		/*
-		 * Initialize the inner node
-		 */
-		resVect[0] = ExecEvalIter((Iter *) fjNode->fj_innerNode->expr,
-								  econtext,
-								  &isNullVect[0],
-								  &isDone);
-		if (isDone)
-			isNullVect[0] = alwaysDone[0] = true;
-		else
-			alwaysDone[0] = false;
-
-		/*
-		 * Mark the Fjoin as initialized now.
-		 */
-		fjNode->fj_initialized = TRUE;
-
-		/*
-		 * If the inner node is always done, then we are done for now
-		 */
-		if (isDone)
-			return;
-	}
-	else
-	{
-		/*
-		 * If we're already initialized, all we need to do is get the next
-		 * inner result and pair it up with the existing outer node result
-		 * vector.	Watch out for the degenerate case, where the inner
-		 * node never returns results.
-		 */
-
-		/*
-		 * Fill in nulls for every function that is always done.
-		 */
-		for (curNode = fjNode->fj_nNodes - 1; curNode >= 0; curNode--)
-			isNullVect[curNode] = alwaysDone[curNode];
-
-		if (alwaysDone[0] == true)
-		{
-			*fj_isDone = FjoinBumpOuterNodes(tlist,
-											 econtext,
-											 resVect,
-											 isNullVect);
-			return;
-		}
-		else
-			resVect[0] = ExecEvalIter((Iter *) fjNode->fj_innerNode->expr,
-									  econtext,
-									  &isNullVect[0],
-									  &isDone);
-	}
-
-	/*
-	 * if the inner node is done
-	 */
-	if (isDone)
-	{
-		*fj_isDone = FjoinBumpOuterNodes(tlist,
-										 econtext,
-										 resVect,
-										 isNullVect);
-		if (*fj_isDone)
-			return;
-
-		resVect[0] = ExecEvalIter((Iter *) fjNode->fj_innerNode->expr,
-								  econtext,
-								  &isNullVect[0],
-								  &isDone);
-
-	}
-#endif
-	return;
-}
-
-#ifdef SETS_FIXED
-static bool
-FjoinBumpOuterNodes(TargetEntry *tlist,
-					ExprContext *econtext,
-					DatumPtr results,
-					char *nulls)
-{
-	bool		funcIsDone = true;
-	Fjoin	   *fjNode = tlist->fjoin;
-	char	   *alwaysDone = fjNode->fj_alwaysDone;
-	List	   *outerList = lnext(tlist);
-	List	   *trailers = lnext(tlist);
-	int			trailNode = 1;
-	int			curNode = 1;
-
-	/*
-	 * Run through list of functions until we get to one that isn't yet
-	 * done returning values.  Watch out for funcs that are always done.
-	 */
-	while ((funcIsDone == true) && (outerList != NIL))
-	{
-		TargetEntry *tle = lfirst(outerList);
-
-		if (alwaysDone[curNode] == true)
-			nulls[curNode] = 'n';
-		else
-			results[curNode] = ExecEvalIter((Iter) tle->expr,
-											econtext,
-											&nulls[curNode],
-											&funcIsDone);
-		curNode++;
-		outerList = lnext(outerList);
-	}
-
-	/*
-	 * If every function is done, then we are done flattening. Mark the
-	 * Fjoin node uninitialized, it is time to get the next tuple from the
-	 * plan and redo all of the flattening.
-	 */
-	if (funcIsDone)
-	{
-		set_fj_initialized(fjNode, false);
-		return true;
-	}
-
-	/*
-	 * We found a function that wasn't done.  Now re-run every function
-	 * before it.  As usual watch out for functions that are always done.
-	 */
-	trailNode = 1;
-	while (trailNode != curNode - 1)
-	{
-		TargetEntry *tle = lfirst(trailers);
-
-		if (alwaysDone[trailNode] != true)
-			results[trailNode] = ExecEvalIter((Iter) tle->expr,
-											  econtext,
-											  &nulls[trailNode],
-											  &funcIsDone);
-		trailNode++;
-		trailers = lnext(trailers);
-	}
-	return false;
-}
-
-#endif

src/backend/executor/execQual.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.92 2002/05/12 20:10:02 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.93 2002/05/12 23:43:02 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -35,7 +35,6 @@
 #include "postgres.h"
 
 #include "access/heapam.h"
-#include "executor/execFlatten.h"
 #include "executor/execdebug.h"
 #include "executor/functions.h"
 #include "executor/nodeSubplan.h"
@@ -1336,12 +1335,6 @@ ExecEvalExpr(Node *expression,
 		case T_Param:
 			retDatum = ExecEvalParam((Param *) expression, econtext, isNull);
 			break;
-		case T_Iter:
-			retDatum = ExecEvalIter((Iter *) expression,
-									econtext,
-									isNull,
-									isDone);
-			break;
 		case T_Aggref:
 			retDatum = ExecEvalAggref((Aggref *) expression, econtext, isNull);
 			break;

src/backend/nodes/copyfuncs.c

@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.183 2002/05/12 20:10:02 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.184 2002/05/12 23:43:02 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -764,6 +764,7 @@ _copyOper(Oper *from)
 	newnode->opno = from->opno;
 	newnode->opid = from->opid;
 	newnode->opresulttype = from->opresulttype;
+	newnode->opretset = from->opretset;
 	/* Do not copy the run-time state, if any */
 	newnode->op_fcache = NULL;
 
@@ -852,7 +853,8 @@ _copyFunc(Func *from)
 	 * copy remainder of node
 	 */
 	newnode->funcid = from->funcid;
-	newnode->functype = from->functype;
+	newnode->funcresulttype = from->funcresulttype;
+	newnode->funcretset = from->funcretset;
 	/* Do not copy the run-time state, if any */
 	newnode->func_fcache = NULL;
 
@@ -1433,17 +1435,6 @@ _copyJoinInfo(JoinInfo *from)
 	return newnode;
 }
 
-static Iter *
-_copyIter(Iter *from)
-{
-	Iter	   *newnode = makeNode(Iter);
-
-	Node_Copy(from, newnode, iterexpr);
-	newnode->itertype = from->itertype;
-
-	return newnode;
-}
-
 static Stream *
 _copyStream(Stream *from)
 {
@@ -2729,9 +2720,6 @@ copyObject(void *from)
 		case T_ArrayRef:
 			retval = _copyArrayRef(from);
 			break;
-		case T_Iter:
-			retval = _copyIter(from);
-			break;
 		case T_FieldSelect:
 			retval = _copyFieldSelect(from);
 			break;

src/backend/nodes/equalfuncs.c

@@ -20,7 +20,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.131 2002/05/12 20:10:03 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.132 2002/05/12 23:43:02 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -130,6 +130,8 @@ _equalOper(Oper *a, Oper *b)
 		return false;
 	if (a->opresulttype != b->opresulttype)
 		return false;
+	if (a->opretset != b->opretset)
+		return false;
 
 	/*
 	 * We do not examine opid or op_fcache, since these are logically
@@ -139,7 +141,8 @@ _equalOper(Oper *a, Oper *b)
 	 * (Besides, op_fcache is executor state, which we don't check --- see
 	 * notes at head of file.)
 	 *
-	 * It's probably not really necessary to check opresulttype either...
+	 * It's probably not really necessary to check opresulttype or opretset,
+	 * either...
 	 */
 
 	return true;
@@ -210,7 +213,9 @@ _equalFunc(Func *a, Func *b)
 {
 	if (a->funcid != b->funcid)
 		return false;
-	if (a->functype != b->functype)
+	if (a->funcresulttype != b->funcresulttype)
+		return false;
+	if (a->funcretset != b->funcretset)
 		return false;
 	/* Note we do not look at func_fcache; see notes for _equalOper */
 
@@ -538,12 +543,6 @@ _equalJoinInfo(JoinInfo *a, JoinInfo *b)
 	return true;
 }
 
-static bool
-_equalIter(Iter *a, Iter *b)
-{
-	return equal(a->iterexpr, b->iterexpr);
-}
-
 static bool
 _equalStream(Stream *a, Stream *b)
 {
@@ -1884,9 +1883,6 @@ equal(void *a, void *b)
 		case T_ArrayRef:
 			retval = _equalArrayRef(a, b);
 			break;
-		case T_Iter:
-			retval = _equalIter(a, b);
-			break;
 		case T_RelabelType:
 			retval = _equalRelabelType(a, b);
 			break;

src/backend/nodes/makefuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/makefuncs.c,v 1.31 2002/04/16 23:08:10 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/makefuncs.c,v 1.32 2002/05/12 23:43:02 tgl Exp $
  */
 #include "postgres.h"
 
@@ -56,13 +56,15 @@ makeSimpleA_Expr(int oper, const char *name,
 Oper *
 makeOper(Oid opno,
 		 Oid opid,
-		 Oid opresulttype)
+		 Oid opresulttype,
+		 bool opretset)
 {
 	Oper	   *oper = makeNode(Oper);
 
 	oper->opno = opno;
 	oper->opid = opid;
 	oper->opresulttype = opresulttype;
+	oper->opretset = opretset;
 	oper->op_fcache = NULL;
 	return oper;
 }

src/backend/nodes/outfuncs.c

@@ -5,7 +5,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *	$Header: /cvsroot/pgsql/src/backend/nodes/outfuncs.c,v 1.158 2002/05/12 20:10:03 tgl Exp $
+ *	$Header: /cvsroot/pgsql/src/backend/nodes/outfuncs.c,v 1.159 2002/05/12 23:43:02 tgl Exp $
  *
  * NOTES
  *	  Every (plan) node in POSTGRES has an associated "out" routine which
@@ -850,9 +850,11 @@ _outArrayRef(StringInfo str, ArrayRef *node)
 static void
 _outFunc(StringInfo str, Func *node)
 {
-	appendStringInfo(str, " FUNC :funcid %u :functype %u ",
+	appendStringInfo(str,
+					 " FUNC :funcid %u :funcresulttype %u :funcretset %s ",
 					 node->funcid,
-					 node->functype);
+					 node->funcresulttype,
+					 booltostr(node->funcretset));
 }
 
 /*
@@ -862,10 +864,11 @@ static void
 _outOper(StringInfo str, Oper *node)
 {
 	appendStringInfo(str,
-					 " OPER :opno %u :opid %u :opresulttype %u ",
+					 " OPER :opno %u :opid %u :opresulttype %u :opretset %s ",
 					 node->opno,
 					 node->opid,
-					 node->opresulttype);
+					 node->opresulttype,
+					 booltostr(node->opretset));
 }
 
 /*
@@ -1246,13 +1249,6 @@ _outDatum(StringInfo str, Datum value, int typlen, bool typbyval)
 	}
 }
 
-static void
-_outIter(StringInfo str, Iter *node)
-{
-	appendStringInfo(str, " ITER :iterexpr ");
-	_outNode(str, node->iterexpr);
-}
-
 static void
 _outStream(StringInfo str, Stream *node)
 {
@@ -1731,9 +1727,6 @@ _outNode(StringInfo str, void *obj)
 			case T_JoinInfo:
 				_outJoinInfo(str, obj);
 				break;
-			case T_Iter:
-				_outIter(str, obj);
-				break;
 			case T_Stream:
 				_outStream(str, obj);
 				break;

src/backend/nodes/readfuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.121 2002/05/12 20:10:03 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.122 2002/05/12 23:43:02 tgl Exp $
  *
  * NOTES
  *	  Most of the read functions for plan nodes are tested. (In fact, they
@@ -1083,9 +1083,13 @@ _readFunc(void)
 	token = pg_strtok(&length); /* now read it */
 	local_node->funcid = atooid(token);
 
-	token = pg_strtok(&length); /* get :functype */
+	token = pg_strtok(&length); /* get :funcresulttype */
 	token = pg_strtok(&length); /* now read it */
-	local_node->functype = atooid(token);
+	local_node->funcresulttype = atooid(token);
+
+	token = pg_strtok(&length); /* get :funcretset */
+	token = pg_strtok(&length); /* now read it */
+	local_node->funcretset = strtobool(token);
 
 	local_node->func_fcache = NULL;
 
@@ -1119,6 +1123,10 @@ _readOper(void)
 	token = pg_strtok(&length); /* now read it */
 	local_node->opresulttype = atooid(token);
 
+	token = pg_strtok(&length); /* get :opretset */
+	token = pg_strtok(&length); /* now read it */
+	local_node->opretset = strtobool(token);
+
 	local_node->op_fcache = NULL;
 
 	return local_node;
@@ -1991,26 +1999,6 @@ _readJoinInfo(void)
 	return local_node;
 }
 
-/* ----------------
- *		_readIter()
- *
- * ----------------
- */
-static Iter *
-_readIter(void)
-{
-	Iter	   *local_node;
-	char	   *token;
-	int			length;
-
-	local_node = makeNode(Iter);
-
-	token = pg_strtok(&length); /* eat :iterexpr */
-	local_node->iterexpr = nodeRead(true);		/* now read it */
-
-	return local_node;
-}
-
 
 /* ----------------
  *		parsePlanString
@@ -2124,8 +2112,6 @@ parsePlanString(void)
 		return_value = _readRestrictInfo();
 	else if (length == 8 && strncmp(token, "JOININFO", length) == 0)
 		return_value = _readJoinInfo();
-	else if (length == 4 && strncmp(token, "ITER", length) == 0)
-		return_value = _readIter();
 	else if (length == 5 && strncmp(token, "QUERY", length) == 0)
 		return_value = _readQuery();
 	else if (length == 6 && strncmp(token, "NOTIFY", length) == 0)

src/backend/optimizer/README

@@ -42,7 +42,8 @@ base rels of the query.
 Possible Paths for a primitive table relation include plain old sequential
 scan, plus index scans for any indexes that exist on the table.  A subquery
 base relation just has one Path, a "SubqueryScan" path (which links to the
-subplan that was built by a recursive invocation of the planner).
+subplan that was built by a recursive invocation of the planner).  Likewise
+a function-RTE base relation has only one possible Path.
 
 Joins always occur using two RelOptInfos.  One is outer, the other inner.
 Outers drive lookups of values in the inner.  In a nested loop, lookups of

src/backend/optimizer/path/allpaths.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/allpaths.c,v 1.84 2002/05/12 20:10:03 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/allpaths.c,v 1.85 2002/05/12 23:43:02 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -312,8 +312,8 @@ set_subquery_pathlist(Query *root, RelOptInfo *rel,
 	 * checking that seems more work than it's worth.  In any case, a
 	 * plain DISTINCT is safe to push down past.)
 	 *
-	 * 3. If the subquery has any ITER nodes (ie, functions returning sets)
-	 * in its target list, we do not push down any quals, since the quals
+	 * 3. If the subquery has any functions returning sets in its target list,
+	 * we do not push down any quals, since the quals
 	 * might refer to those tlist items, which would mean we'd introduce
 	 * functions-returning-sets into the subquery's WHERE/HAVING quals.
 	 * (It'd be sufficient to not push down quals that refer to those
@@ -333,7 +333,7 @@ set_subquery_pathlist(Query *root, RelOptInfo *rel,
 		subquery->limitOffset == NULL &&
 		subquery->limitCount == NULL &&
 		!has_distinct_on_clause(subquery) &&
-		!contain_iter_clause((Node *) subquery->targetList))
+		!expression_returns_set((Node *) subquery->targetList))
 	{
 		/* OK to consider pushing down individual quals */
 		List	   *upperrestrictlist = NIL;

src/backend/optimizer/path/indxpath.c

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.116 2002/04/16 23:08:10 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.117 2002/05/12 23:43:02 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1316,7 +1316,8 @@ pred_test_simple_clause(Expr *predicate, Node *clause)
 	 */
 	test_oper = makeOper(test_op,		/* opno */
 						 InvalidOid,	/* opid */
-						 BOOLOID);		/* opresulttype */
+						 BOOLOID,		/* opresulttype */
+						 false);		/* opretset */
 	replace_opid(test_oper);
 	test_expr = make_opclause(test_oper,
 							  (Var *) clause_const,
@@ -2020,7 +2021,7 @@ prefix_quals(Var *leftop, Oid expr_op,
 		if (oproid == InvalidOid)
 			elog(ERROR, "prefix_quals: no = operator for type %u", datatype);
 		con = string_to_const(prefix, datatype);
-		op = makeOper(oproid, InvalidOid, BOOLOID);
+		op = makeOper(oproid, InvalidOid, BOOLOID, false);
 		expr = make_opclause(op, leftop, (Var *) con);
 		result = makeList1(expr);
 		return result;
@@ -2035,7 +2036,7 @@ prefix_quals(Var *leftop, Oid expr_op,
 	if (oproid == InvalidOid)
 		elog(ERROR, "prefix_quals: no >= operator for type %u", datatype);
 	con = string_to_const(prefix, datatype);
-	op = makeOper(oproid, InvalidOid, BOOLOID);
+	op = makeOper(oproid, InvalidOid, BOOLOID, false);
 	expr = make_opclause(op, leftop, (Var *) con);
 	result = makeList1(expr);
 
@@ -2051,7 +2052,7 @@ prefix_quals(Var *leftop, Oid expr_op,
 		if (oproid == InvalidOid)
 			elog(ERROR, "prefix_quals: no < operator for type %u", datatype);
 		con = string_to_const(greaterstr, datatype);
-		op = makeOper(oproid, InvalidOid, BOOLOID);
+		op = makeOper(oproid, InvalidOid, BOOLOID, false);
 		expr = make_opclause(op, leftop, (Var *) con);
 		result = lappend(result, expr);
 		pfree(greaterstr);
@@ -2116,7 +2117,7 @@ network_prefix_quals(Var *leftop, Oid expr_op, Datum rightop)
 
 	opr1right = network_scan_first(rightop);
 
-	op = makeOper(opr1oid, InvalidOid, BOOLOID);
+	op = makeOper(opr1oid, InvalidOid, BOOLOID, false);
 	expr = make_opclause(op, leftop,
 						 (Var *) makeConst(datatype, -1, opr1right,
 										   false, false, false, false));
@@ -2131,7 +2132,7 @@ network_prefix_quals(Var *leftop, Oid expr_op, Datum rightop)
 
 	opr2right = network_scan_last(rightop);
 
-	op = makeOper(opr2oid, InvalidOid, BOOLOID);
+	op = makeOper(opr2oid, InvalidOid, BOOLOID, false);
 	expr = make_opclause(op, leftop,
 						 (Var *) makeConst(datatype, -1, opr2right,
 										   false, false, false, false));

src/backend/optimizer/path/pathkeys.c

@@ -11,7 +11,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.37 2002/03/12 00:51:44 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.38 2002/05/12 23:43:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -518,7 +518,8 @@ build_index_pathkeys(Query *root,
 		List	   *funcargs = NIL;
 
 		funcnode->funcid = index->indproc;
-		funcnode->functype = get_func_rettype(index->indproc);
+		funcnode->funcresulttype = get_func_rettype(index->indproc);
+		funcnode->funcretset = false; /* can never be a set */
 		funcnode->func_fcache = NULL;
 
 		while (*indexkeys != 0)

src/backend/optimizer/plan/initsplan.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.69 2002/04/28 19:54:28 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.70 2002/05/12 23:43:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -764,9 +764,10 @@ process_implied_equality(Query *root, Node *item1, Node *item2,
 	clause = makeNode(Expr);
 	clause->typeOid = BOOLOID;
 	clause->opType = OP_EXPR;
-	clause->oper = (Node *) makeOper(oprid(eq_operator),		/* opno */
+	clause->oper = (Node *) makeOper(oprid(eq_operator),/* opno */
 									 InvalidOid,		/* opid */
-									 BOOLOID);	/* operator result type */
+									 BOOLOID,			/* opresulttype */
+									 false);			/* opretset */
 	clause->args = makeList2(item1, item2);
 
 	ReleaseSysCache(eq_operator);

src/backend/optimizer/plan/planner.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.116 2002/04/28 19:54:28 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.117 2002/05/12 23:43:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -498,7 +498,7 @@ is_simple_subquery(Query *subquery)
 	 * set-returning functions into places where they mustn't go,
 	 * such as quals of higher queries.
 	 */
-	if (contain_iter_clause((Node *) subquery->targetList))
+	if (expression_returns_set((Node *) subquery->targetList))
 		return false;
 
 	/*

src/backend/optimizer/prep/prepqual.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepqual.c,v 1.30 2001/10/25 05:49:33 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepqual.c,v 1.31 2002/05/12 23:43:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -502,7 +502,8 @@ push_nots(Expr *qual)
 		{
 			Oper	   *op = (Oper *) makeOper(negator,
 											   InvalidOid,
-											   oper->opresulttype);
+											   oper->opresulttype,
+											   oper->opretset);
 
 			return make_opclause(op, get_leftop(qual), get_rightop(qual));
 		}

src/backend/optimizer/util/clauses.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.98 2002/05/12 20:10:03 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.99 2002/05/12 23:43:03 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -47,7 +47,7 @@ typedef struct
 
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool pull_agg_clause_walker(Node *node, List **listptr);
-static bool contain_iter_clause_walker(Node *node, void *context);
+static bool expression_returns_set_walker(Node *node, void *context);
 static bool contain_subplans_walker(Node *node, void *context);
 static bool pull_subplans_walker(Node *node, List **listptr);
 static bool check_subplans_for_ungrouped_vars_walker(Node *node,
@@ -74,7 +74,7 @@ make_clause(int type, Node *oper, List *args)
 			expr->typeOid = ((Oper *) oper)->opresulttype;
 			break;
 		case FUNC_EXPR:
-			expr->typeOid = ((Func *) oper)->functype;
+			expr->typeOid = ((Func *) oper)->funcresulttype;
 			break;
 		default:
 			elog(ERROR, "make_clause: unsupported type %d", type);
@@ -195,7 +195,7 @@ make_funcclause(Func *func, List *funcargs)
 {
 	Expr	   *expr = makeNode(Expr);
 
-	expr->typeOid = func->functype;
+	expr->typeOid = func->funcresulttype;
 	expr->opType = FUNC_EXPR;
 	expr->oper = (Node *) func;
 	expr->args = funcargs;
@@ -453,36 +453,61 @@ pull_agg_clause_walker(Node *node, List **listptr)
 
 
 /*****************************************************************************
- *		Iter clause manipulation
+ *		Support for expressions returning sets
  *****************************************************************************/
 
 /*
- * contain_iter_clause
- *	  Recursively search for Iter nodes within a clause.
+ * expression_returns_set
+ *	  Test whethe an expression returns a set result.
  *
- *	  Returns true if any Iter found.
- *
- * XXX Iter is a crock.  It'd be better to look directly at each function
- * or operator to see if it can return a set.  However, that would require
- * a lot of extra cycles as things presently stand.  The return-type info
- * for function and operator nodes should be extended to include whether
- * the return is a set.
+ * Because we use expression_tree_walker(), this can also be applied to
+ * whole targetlists; it'll produce TRUE if any one of the tlist items
+ * returns a set.
  */
 bool
-contain_iter_clause(Node *clause)
+expression_returns_set(Node *clause)
 {
-	return contain_iter_clause_walker(clause, NULL);
+	return expression_returns_set_walker(clause, NULL);
 }
 
 static bool
-contain_iter_clause_walker(Node *node, void *context)
+expression_returns_set_walker(Node *node, void *context)
 {
 	if (node == NULL)
 		return false;
-	if (IsA(node, Iter))
-		return true;			/* abort the tree traversal and return
-								 * true */
-	return expression_tree_walker(node, contain_iter_clause_walker, context);
+	if (IsA(node, Expr))
+	{
+		Expr   *expr = (Expr *) node;
+
+		switch (expr->opType)
+		{
+			case OP_EXPR:
+				if (((Oper *) expr->oper)->opretset)
+					return true;
+				/* else fall through to check args */
+				break;
+			case FUNC_EXPR:
+				if (((Func *) expr->oper)->funcretset)
+					return true;
+				/* else fall through to check args */
+				break;
+			case OR_EXPR:
+			case AND_EXPR:
+			case NOT_EXPR:
+				/* Booleans can't return a set, so no need to recurse */
+				return false;
+			case SUBPLAN_EXPR:
+				/* Subplans can't presently return sets either */
+				return false;
+		}
+	}
+	/* Avoid recursion for some other cases that can't return a set */
+	if (IsA(node, Aggref))
+		return false;
+	if (IsA(node, SubLink))
+		return false;
+	return expression_tree_walker(node, expression_returns_set_walker,
+								  context);
 }
 
 /*****************************************************************************
@@ -1043,7 +1068,8 @@ CommuteClause(Expr *clause)
 
 	commu = makeOper(optup->t_data->t_oid,
 					 commuTup->oprcode,
-					 commuTup->oprresult);
+					 commuTup->oprresult,
+					 ((Oper *) clause->oper)->opretset);
 
 	ReleaseSysCache(optup);
 
@@ -1073,8 +1099,7 @@ CommuteClause(Expr *clause)
  * results even with constant inputs, "nextval()" being the classic
  * example.  Functions that are not marked "immutable" in pg_proc
  * will not be pre-evaluated here, although we will reduce their
- * arguments as far as possible.  Functions that are the arguments
- * of Iter nodes are also not evaluated.
+ * arguments as far as possible.
  *
  * We assume that the tree has already been type-checked and contains
  * only operators and functions that are reasonable to try to execute.
@@ -1398,37 +1423,6 @@ eval_const_expressions_mutator(Node *node, void *context)
 		newcase->defresult = defresult;
 		return (Node *) newcase;
 	}
-	if (IsA(node, Iter))
-	{
-		/*
-		 * The argument of an Iter is normally a function call. We must
-		 * not try to eliminate the function, but we can try to simplify
-		 * its arguments.  If, by chance, the arg is NOT a function then
-		 * we go ahead and try to simplify it (by falling into
-		 * expression_tree_mutator). Is that the right thing?
-		 */
-		Iter	   *iter = (Iter *) node;
-
-		if (is_funcclause(iter->iterexpr))
-		{
-			Expr	   *func = (Expr *) iter->iterexpr;
-			Expr	   *newfunc;
-			Iter	   *newiter;
-
-			newfunc = makeNode(Expr);
-			newfunc->typeOid = func->typeOid;
-			newfunc->opType = func->opType;
-			newfunc->oper = func->oper;
-			newfunc->args = (List *)
-				expression_tree_mutator((Node *) func->args,
-										eval_const_expressions_mutator,
-										(void *) context);
-			newiter = makeNode(Iter);
-			newiter->iterexpr = (Node *) newfunc;
-			newiter->itertype = iter->itertype;
-			return (Node *) newiter;
-		}
-	}
 
 	/*
 	 * For any node type not handled above, we recurse using
@@ -1501,8 +1495,9 @@ simplify_op_or_func(Expr *expr, List *args)
 	 * Get the function procedure's OID and look to see whether it is
 	 * marked immutable.
 	 *
-	 * XXX would it be better to take the result type from the pg_proc tuple,
-	 * rather than the Oper or Func node?
+	 * Note we take the result type from the Oper or Func node, not the
+	 * pg_proc tuple; probably necessary for binary-compatibility cases.
+	 *
 	 */
 	if (expr->opType == OP_EXPR)
 	{
@@ -1517,7 +1512,7 @@ simplify_op_or_func(Expr *expr, List *args)
 		Func	   *func = (Func *) expr->oper;
 
 		funcid = func->funcid;
-		result_typeid = func->functype;
+		result_typeid = func->funcresulttype;
 	}
 
 	/*
@@ -1747,8 +1742,6 @@ expression_tree_walker(Node *node,
 			break;
 		case T_Aggref:
 			return walker(((Aggref *) node)->target, context);
-		case T_Iter:
-			return walker(((Iter *) node)->iterexpr, context);
 		case T_ArrayRef:
 			{
 				ArrayRef   *aref = (ArrayRef *) node;
@@ -2083,16 +2076,6 @@ expression_tree_mutator(Node *node,
 				return (Node *) newnode;
 			}
 			break;
-		case T_Iter:
-			{
-				Iter	   *iter = (Iter *) node;
-				Iter	   *newnode;
-
-				FLATCOPY(newnode, iter, Iter);
-				MUTATE(newnode->iterexpr, iter->iterexpr, Node *);
-				return (Node *) newnode;
-			}
-			break;
 		case T_ArrayRef:
 			{
 				ArrayRef   *arrayref = (ArrayRef *) node;

src/backend/parser/parse_clause.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.91 2002/05/12 20:10:04 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.92 2002/05/12 23:43:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -285,14 +285,7 @@ transformJoinUsingClause(ParseState *pstate, List *leftVars, List *rightVars)
 	 */
 	result = transformExpr(pstate, result);
 
-	/*
-	 * We expect the result to yield bool directly, otherwise complain. We
-	 * could try coerce_to_boolean() here, but it seems likely that an "="
-	 * operator that doesn't return bool is wrong anyway.
-	 */
-	if (exprType(result) != BOOLOID)
-		elog(ERROR, "JOIN/USING clause must return type boolean, not type %s",
-			 format_type_be(exprType(result)));
+	result = coerce_to_boolean(result, "JOIN/USING");
 
 	return result;
 }	/* transformJoinUsingClause() */
@@ -326,9 +319,7 @@ transformJoinOnClause(ParseState *pstate, JoinExpr *j,
 	/* This part is just like transformWhereClause() */
 	result = transformExpr(pstate, j->quals);
 
-	if (!coerce_to_boolean(pstate, &result))
-		elog(ERROR, "JOIN/ON clause must return type boolean, not type %s",
-			 format_type_be(exprType(result)));
+	result = coerce_to_boolean(result, "JOIN/ON");
 
 	pstate->p_namespace = save_namespace;
 
@@ -486,14 +477,7 @@ transformRangeFunction(ParseState *pstate, RangeFunction *r)
 		elog(ERROR, "cannot use subselect in FROM function expression");
 
 	/*
-	 * Remove any Iter nodes added by parse_func.c.  We oughta get rid of
-	 * Iter completely ...
-	 */
-	while (funcexpr && IsA(funcexpr, Iter))
-		funcexpr = ((Iter *) funcexpr)->iterexpr;
-
-	/*
-	 * Insist we now have a bare function call (explain.c is the only place
+	 * Insist we have a bare function call (explain.c is the only place
 	 * that depends on this, I think).  If this fails, it's probably because
 	 * transformExpr interpreted the function notation as a type coercion.
 	 */
@@ -947,9 +931,7 @@ transformWhereClause(ParseState *pstate, Node *clause)
 
 	qual = transformExpr(pstate, clause);
 
-	if (!coerce_to_boolean(pstate, &qual))
-		elog(ERROR, "WHERE clause must return type boolean, not type %s",
-			 format_type_be(exprType(qual)));
+	qual = coerce_to_boolean(qual, "WHERE");
 
 	return qual;
 }

src/backend/parser/parse_coerce.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.71 2002/04/25 02:56:55 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.72 2002/05/12 23:43:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -313,26 +313,37 @@ coerce_type_typmod(ParseState *pstate, Node *node,
 
 /* coerce_to_boolean()
  *		Coerce an argument of a construct that requires boolean input
- *		(AND, OR, NOT, etc).
+ *		(AND, OR, NOT, etc).  Also check that input is not a set.
  *
- * If successful, update *pnode to be the transformed argument (if any
- * transformation is needed), and return TRUE.	If fail, return FALSE.
- * (The caller must check for FALSE and emit a suitable error message.)
+ * Returns the possibly-transformed node tree.
  */
-bool
-coerce_to_boolean(ParseState *pstate, Node **pnode)
+Node *
+coerce_to_boolean(Node *node, const char *constructName)
 {
-	Oid			inputTypeId = exprType(*pnode);
+	Oid			inputTypeId = exprType(node);
 	Oid			targetTypeId;
 
-	if (inputTypeId == BOOLOID)
-		return true;			/* no work */
-	targetTypeId = BOOLOID;
-	if (!can_coerce_type(1, &inputTypeId, &targetTypeId, false))
-		return false;			/* fail, but let caller choose error msg */
-	*pnode = coerce_type(pstate, *pnode, inputTypeId, targetTypeId, -1,
-						 false);
-	return true;
+	if (inputTypeId != BOOLOID)
+	{
+		targetTypeId = BOOLOID;
+		if (!can_coerce_type(1, &inputTypeId, &targetTypeId, false))
+		{
+			/* translator: first %s is name of a SQL construct, eg WHERE */
+			elog(ERROR, "Argument of %s must be type boolean, not type %s",
+				 constructName, format_type_be(inputTypeId));
+		}
+		node = coerce_type(NULL, node, inputTypeId, targetTypeId, -1,
+						   false);
+	}
+
+	if (expression_returns_set(node))
+	{
+		/* translator: %s is name of a SQL construct, eg WHERE */
+		elog(ERROR, "Argument of %s must not be a set function",
+			 constructName);
+	}
+
+	return node;
 }
 
 
@@ -782,7 +793,8 @@ build_func_call(Oid funcid, Oid rettype, List *args)
 
 	funcnode = makeNode(Func);
 	funcnode->funcid = funcid;
-	funcnode->functype = rettype;
+	funcnode->funcresulttype = rettype;
+	funcnode->funcretset = false; /* only possible case here */
 	funcnode->func_fcache = NULL;
 
 	expr = makeNode(Expr);

src/backend/parser/parse_expr.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.116 2002/04/28 00:49:12 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.117 2002/05/12 23:43:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -31,6 +31,7 @@
 #include "parser/parse_target.h"
 #include "parser/parse_type.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
 #include "utils/syscache.h"
 
 
@@ -230,15 +231,8 @@ transformExpr(ParseState *pstate, Node *expr)
 															  a->rexpr);
 							Expr	   *expr = makeNode(Expr);
 
-							if (!coerce_to_boolean(pstate, &lexpr))
-								elog(ERROR, "left-hand side of AND is type '%s', not '%s'",
-									 format_type_be(exprType(lexpr)),
-									 format_type_be(BOOLOID));
-
-							if (!coerce_to_boolean(pstate, &rexpr))
-								elog(ERROR, "right-hand side of AND is type '%s', not '%s'",
-									 format_type_be(exprType(rexpr)),
-									 format_type_be(BOOLOID));
+							lexpr = coerce_to_boolean(lexpr, "AND");
+							rexpr = coerce_to_boolean(rexpr, "AND");
 
 							expr->typeOid = BOOLOID;
 							expr->opType = AND_EXPR;
@@ -254,15 +248,8 @@ transformExpr(ParseState *pstate, Node *expr)
 															  a->rexpr);
 							Expr	   *expr = makeNode(Expr);
 
-							if (!coerce_to_boolean(pstate, &lexpr))
-								elog(ERROR, "left-hand side of OR is type '%s', not '%s'",
-									 format_type_be(exprType(lexpr)),
-									 format_type_be(BOOLOID));
-
-							if (!coerce_to_boolean(pstate, &rexpr))
-								elog(ERROR, "right-hand side of OR is type '%s', not '%s'",
-									 format_type_be(exprType(rexpr)),
-									 format_type_be(BOOLOID));
+							lexpr = coerce_to_boolean(lexpr, "OR");
+							rexpr = coerce_to_boolean(rexpr, "OR");
 
 							expr->typeOid = BOOLOID;
 							expr->opType = OR_EXPR;
@@ -276,10 +263,7 @@ transformExpr(ParseState *pstate, Node *expr)
 															  a->rexpr);
 							Expr	   *expr = makeNode(Expr);
 
-							if (!coerce_to_boolean(pstate, &rexpr))
-								elog(ERROR, "argument to NOT is type '%s', not '%s'",
-									 format_type_be(exprType(rexpr)),
-									 format_type_be(BOOLOID));
+							rexpr = coerce_to_boolean(rexpr, "NOT");
 
 							expr->typeOid = BOOLOID;
 							expr->opType = NOT_EXPR;
@@ -426,9 +410,15 @@ transformExpr(ParseState *pstate, Node *expr)
 								 opname, typeidTypeName(opform->oprresult),
 								 typeidTypeName(BOOLOID));
 
+						if (get_func_retset(opform->oprcode))
+							elog(ERROR, "'%s' must not return a set"
+								 " to be used with quantified predicate subquery",
+								 opname);
+
 						newop = makeOper(oprid(optup),	/* opno */
 										 InvalidOid,	/* opid */
-										 opform->oprresult);
+										 opform->oprresult,
+										 false);
 						sublink->oper = lappend(sublink->oper, newop);
 						ReleaseSysCache(optup);
 					}
@@ -467,8 +457,7 @@ transformExpr(ParseState *pstate, Node *expr)
 					}
 					neww->expr = transformExpr(pstate, warg);
 
-					if (!coerce_to_boolean(pstate, &neww->expr))
-						elog(ERROR, "WHEN clause must have a boolean result");
+					neww->expr = coerce_to_boolean(neww->expr, "CASE/WHEN");
 
 					/*
 					 * result is NULL for NULLIF() construct - thomas
@@ -553,42 +542,38 @@ transformExpr(ParseState *pstate, Node *expr)
 		case T_BooleanTest:
 			{
 				BooleanTest *b = (BooleanTest *) expr;
+				const char *clausename;
 
-				b->arg = transformExpr(pstate, b->arg);
-
-				if (!coerce_to_boolean(pstate, &b->arg))
+				switch (b->booltesttype)
 				{
-					const char *clausename;
+					case IS_TRUE:
+						clausename = "IS TRUE";
+						break;
+					case IS_NOT_TRUE:
+						clausename = "IS NOT TRUE";
+						break;
+					case IS_FALSE:
+						clausename = "IS FALSE";
+						break;
+					case IS_NOT_FALSE:
+						clausename = "IS NOT FALSE";
+						break;
+					case IS_UNKNOWN:
+						clausename = "IS UNKNOWN";
+						break;
+					case IS_NOT_UNKNOWN:
+						clausename = "IS NOT UNKNOWN";
+						break;
+					default:
+						elog(ERROR, "transformExpr: unexpected booltesttype %d",
+							 (int) b->booltesttype);
+						clausename = NULL;	/* keep compiler quiet */
+				}
 
-					switch (b->booltesttype)
-					{
-						case IS_TRUE:
-							clausename = "IS TRUE";
-							break;
-						case IS_NOT_TRUE:
-							clausename = "IS NOT TRUE";
-							break;
-						case IS_FALSE:
-							clausename = "IS FALSE";
-							break;
-						case IS_NOT_FALSE:
-							clausename = "IS NOT FALSE";
-							break;
-						case IS_UNKNOWN:
-							clausename = "IS UNKNOWN";
-							break;
-						case IS_NOT_UNKNOWN:
-							clausename = "IS NOT UNKNOWN";
-							break;
-						default:
-							elog(ERROR, "transformExpr: unexpected booltesttype %d",
-								 (int) b->booltesttype);
-							clausename = NULL;	/* keep compiler quiet */
-					}
+				b->arg = transformExpr(pstate, b->arg);
+
+				b->arg = coerce_to_boolean(b->arg, clausename);
 
-					elog(ERROR, "Argument of %s must be boolean",
-						 clausename);
-				}
 				result = expr;
 				break;
 			}
@@ -833,12 +818,6 @@ exprType(Node *expr)
 
 	switch (nodeTag(expr))
 	{
-		case T_Func:
-			type = ((Func *) expr)->functype;
-			break;
-		case T_Iter:
-			type = ((Iter *) expr)->itertype;
-			break;
 		case T_Var:
 			type = ((Var *) expr)->vartype;
 			break;

src/backend/parser/parse_func.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_func.c,v 1.128 2002/05/12 20:10:04 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_func.c,v 1.129 2002/05/12 23:43:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -280,7 +280,8 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
 		Func	   *funcnode = makeNode(Func);
 
 		funcnode->funcid = funcid;
-		funcnode->functype = rettype;
+		funcnode->funcresulttype = rettype;
+		funcnode->funcretset = retset;
 		funcnode->func_fcache = NULL;
 
 		expr->typeOid = rettype;
@@ -289,21 +290,6 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
 		expr->args = fargs;
 
 		retval = (Node *) expr;
-
-		/*
-		 * if the function returns a set of values, then we need to iterate
-		 * over all the returned values in the executor, so we stick an iter
-		 * node here.  if it returns a singleton, then we don't need the iter
-		 * node.
-		 */
-		if (retset)
-		{
-			Iter	   *iter = makeNode(Iter);
-
-			iter->itertype = rettype;
-			iter->iterexpr = retval;
-			retval = (Node *) iter;
-		}
 	}
 	else
 	{
@@ -1186,26 +1172,6 @@ ParseComplexProjection(ParseState *pstate,
 	 */
 	switch (nodeTag(first_arg))
 	{
-		case T_Iter:
-			{
-				Iter	   *iter = (Iter *) first_arg;
-
-				/*
-				 * If it's an Iter, we stick the FieldSelect
-				 * *inside* the Iter --- this is klugy, but necessary
-				 * because ExecTargetList() currently does the right thing
-				 * only when the Iter node is at the top level of a
-				 * targetlist item.
-				 *
-				 * XXX Iter should go away altogether...
-				 */
-				fselect = setup_field_select(iter->iterexpr,
-											 funcname, argrelid);
-				iter->iterexpr = (Node *) fselect;
-				iter->itertype = fselect->resulttype;
-				return (Node *) iter;
-				break;
-			}
 		case T_Var:
 			{
 				Var		   *var = (Var *) first_arg;

src/backend/parser/parse_node.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_node.c,v 1.64 2002/05/01 19:26:07 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_node.c,v 1.65 2002/05/12 23:43:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -135,7 +135,8 @@ make_op(List *opname, Node *ltree, Node *rtree)
 
 	newop = makeOper(oprid(tup),	/* opno */
 					 InvalidOid,	/* opid */
-					 opform->oprresult);		/* operator result type */
+					 opform->oprresult,	/* opresulttype */
+					 get_func_retset(opform->oprcode));	/* opretset */
 
 	result = makeNode(Expr);
 	result->typeOid = opform->oprresult;

src/backend/utils/adt/ruleutils.c

@@ -3,7 +3,7 @@
  *				back to source text
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.103 2002/05/12 20:10:04 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.104 2002/05/12 23:43:03 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -1673,10 +1673,6 @@ get_rule_expr(Node *node, deparse_context *context)
 			get_agg_expr((Aggref *) node, context);
 			break;
 
-		case T_Iter:
-			get_rule_expr(((Iter *) node)->iterexpr, context);
-			break;
-
 		case T_ArrayRef:
 			{
 				ArrayRef   *aref = (ArrayRef *) node;

src/backend/utils/cache/lsyscache.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/lsyscache.c,v 1.72 2002/04/30 01:26:26 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/lsyscache.c,v 1.73 2002/05/12 23:43:03 tgl Exp $
  *
  * NOTES
  *	  Eventually, the index information should go through here, too.
@@ -612,6 +612,27 @@ get_func_rettype(Oid funcid)
 	return result;
 }
 
+/*
+ * get_func_retset
+ *		Given procedure id, return the function's proretset flag.
+ */
+bool
+get_func_retset(Oid funcid)
+{
+	HeapTuple	tp;
+	bool		result;
+
+	tp = SearchSysCache(PROCOID,
+						ObjectIdGetDatum(funcid),
+						0, 0, 0);
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "Function OID %u does not exist", funcid);
+
+	result = ((Form_pg_proc) GETSTRUCT(tp))->proretset;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*
  * func_volatile
  *		Given procedure id, return the function's provolatile flag.

src/include/catalog/catversion.h

@@ -37,7 +37,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: catversion.h,v 1.130 2002/05/12 20:10:04 tgl Exp $
+ * $Id: catversion.h,v 1.131 2002/05/12 23:43:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	200205121
+#define CATALOG_VERSION_NO	200205122
 
 #endif

src/include/executor/execFlatten.h

-/*-------------------------------------------------------------------------
- *
- * execFlatten.h
- *	  prototypes for execFlatten.c.
- *
- *
- * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- * $Id: execFlatten.h,v 1.16 2001/11/05 17:46:33 momjian Exp $
- *
- *-------------------------------------------------------------------------
- */
-#ifndef EXECFLATTEN_H
-#define EXECFLATTEN_H
-
-#include "nodes/execnodes.h"
-#include "nodes/parsenodes.h"
-
-
-extern Datum ExecEvalIter(Iter *iterNode, ExprContext *econtext,
-			 bool *isNull, ExprDoneCond *isDone);
-
-extern void ExecEvalFjoin(TargetEntry *tlist, ExprContext *econtext,
-			  bool *isNullVect, ExprDoneCond *fj_isDone);
-
-#endif   /* EXECFLATTEN_H */

src/include/nodes/makefuncs.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: makefuncs.h,v 1.35 2002/04/16 23:08:12 tgl Exp $
+ * $Id: makefuncs.h,v 1.36 2002/05/12 23:43:04 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -22,8 +22,9 @@ extern A_Expr *makeSimpleA_Expr(int oper, const char *name,
 								Node *lexpr, Node *rexpr);
 
 extern Oper *makeOper(Oid opno,
-		 Oid opid,
-		 Oid opresulttype);
+					  Oid opid,
+					  Oid opresulttype,
+					  bool opretset);
 
 extern Var *makeVar(Index varno,
 		AttrNumber varattno,

src/include/nodes/nodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: nodes.h,v 1.106 2002/05/12 20:10:04 tgl Exp $
+ * $Id: nodes.h,v 1.107 2002/05/12 23:43:04 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -66,7 +66,6 @@ typedef enum NodeTag
 	T_Func,
 	T_FieldSelect,
 	T_ArrayRef,
-	T_Iter,
 	T_RelabelType,
 	T_RangeTblRef,
 	T_FromExpr,

src/include/nodes/primnodes.h

@@ -10,7 +10,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: primnodes.h,v 1.62 2002/05/12 20:10:05 tgl Exp $
+ * $Id: primnodes.h,v 1.63 2002/05/12 23:43:04 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -151,12 +151,51 @@ typedef struct Expr
 {
 	NodeTag		type;
 	Oid			typeOid;		/* oid of the type of this expression */
-	OpType		opType;			/* type of this expression */
+	OpType		opType;			/* kind of expression */
 	Node	   *oper;			/* operator node if needed (Oper, Func, or
 								 * SubPlan) */
 	List	   *args;			/* arguments to this expression */
 } Expr;
 
+/*
+ * Oper - Expr subnode for an OP_EXPR
+ *
+ * NOTE: in the good old days 'opno' used to be both (or either, or
+ * neither) the pg_operator oid, and/or the pg_proc oid depending
+ * on the postgres module in question (parser->pg_operator,
+ * executor->pg_proc, planner->both), the mood of the programmer,
+ * and the phase of the moon (rumors that it was also depending on the day
+ * of the week are probably false). To make things even more postgres-like
+ * (i.e. a mess) some comments were referring to 'opno' using the name
+ * 'opid'. Anyway, now we have two separate fields, and of course that
+ * immediately removes all bugs from the code...		[ sp :-) ].
+ *
+ * Note also that opid is not necessarily filled in immediately on creation
+ * of the node.  The planner makes sure it is valid before passing the node
+ * tree to the executor, but during parsing/planning opid is typically 0.
+ */
+typedef struct Oper
+{
+	NodeTag		type;
+	Oid			opno;			/* PG_OPERATOR OID of the operator */
+	Oid			opid;			/* PG_PROC OID of underlying function */
+	Oid			opresulttype;	/* PG_TYPE OID of result value */
+	bool		opretset;		/* true if operator returns set */
+	FunctionCachePtr op_fcache;	/* runtime state, else NULL */
+} Oper;
+
+/*
+ * Func - Expr subnode for a FUNC_EXPR
+ */
+typedef struct Func
+{
+	NodeTag		type;
+	Oid			funcid;			/* PG_PROC OID of the function */
+	Oid			funcresulttype;	/* PG_TYPE OID of result value */
+	bool		funcretset;		/* true if function returns set */
+	FunctionCachePtr func_fcache; /* runtime state, or NULL */
+} Func;
+
 /*
  * Var
  *
@@ -196,37 +235,6 @@ typedef struct Var
 	AttrNumber	varoattno;		/* original value of varattno */
 } Var;
 
-/*--------------------
- * Oper
- *
- * NOTE: in the good old days 'opno' used to be both (or either, or
- * neither) the pg_operator oid, and/or the pg_proc oid depending
- * on the postgres module in question (parser->pg_operator,
- * executor->pg_proc, planner->both), the mood of the programmer,
- * and the phase of the moon (rumors that it was also depending on the day
- * of the week are probably false). To make things even more postgres-like
- * (i.e. a mess) some comments were referring to 'opno' using the name
- * 'opid'. Anyway, now we have two separate fields, and of course that
- * immediately removes all bugs from the code...		[ sp :-) ].
- *
- * Note also that opid is not necessarily filled in immediately on creation
- * of the node.  The planner makes sure it is valid before passing the node
- * tree to the executor, but during parsing/planning opid is typically 0.
- *--------------------
- */
-typedef struct Oper
-{
-	NodeTag		type;
-	Oid			opno;			/* PG_OPERATOR OID of the operator */
-	Oid			opid;			/* PG_PROC OID for the operator's
-								 * underlying function */
-	Oid			opresulttype;
-	/* PG_TYPE OID of the operator's return value */
-	FunctionCachePtr op_fcache;
-	/* runtime state while running the function */
-} Oper;
-
-
 /*
  * Const
  */
@@ -283,39 +291,6 @@ typedef struct Param
 	Oid			paramtype;		/* PG_TYPE OID of the parameter's value */
 } Param;
 
-
-/*
- * Func
- */
-typedef struct Func
-{
-	NodeTag		type;
-	Oid			funcid;			/* PG_PROC OID of the function */
-	Oid			functype;		/* PG_TYPE OID of the function's return
-								 * value */
-	FunctionCachePtr func_fcache;
-
-	/*
-	 * runtime state while running this function. Where we are in the
-	 * execution of the function if it returns more than one value, etc.
-	 * See utils/fcache.h
-	 */
-} Func;
-
-/* ----------------
- * Iter
- *		can anyone explain what this is for?  Seems to have something to do
- *		with evaluation of functions that return sets...
- * ----------------
- */
-typedef struct Iter
-{
-	NodeTag		type;
-	Node	   *iterexpr;
-	Oid			itertype;		/* type of the iter expr (use for type
-								 * checking) */
-} Iter;
-
 /*
  * Aggref
  */

src/include/optimizer/clauses.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: clauses.h,v 1.51 2002/04/05 00:31:35 tgl Exp $
+ * $Id: clauses.h,v 1.52 2002/05/12 23:43:04 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -42,7 +42,7 @@ extern List *make_ands_implicit(Expr *clause);
 extern bool contain_agg_clause(Node *clause);
 extern List *pull_agg_clause(Node *clause);
 
-extern bool contain_iter_clause(Node *clause);
+extern bool expression_returns_set(Node *clause);
 
 extern bool contain_subplans(Node *clause);
 extern List *pull_subplans(Node *clause);

src/include/parser/parse_coerce.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: parse_coerce.h,v 1.42 2002/04/11 20:00:15 tgl Exp $
+ * $Id: parse_coerce.h,v 1.43 2002/05/12 23:43:04 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -45,7 +45,7 @@ extern Node *coerce_type(ParseState *pstate, Node *node, Oid inputTypeId,
 extern Node *coerce_type_typmod(ParseState *pstate, Node *node,
 				   Oid targetTypeId, int32 atttypmod);
 
-extern bool coerce_to_boolean(ParseState *pstate, Node **pnode);
+extern Node *coerce_to_boolean(Node *node, const char *constructName);
 
 extern Oid	select_common_type(List *typeids, const char *context);
 extern Node *coerce_to_common_type(ParseState *pstate, Node *node,

src/include/utils/lsyscache.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: lsyscache.h,v 1.51 2002/04/30 01:26:26 tgl Exp $
+ * $Id: lsyscache.h,v 1.52 2002/05/12 23:43:04 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -39,6 +39,7 @@ extern RegProcedure get_oprrest(Oid opno);
 extern RegProcedure get_oprjoin(Oid opno);
 extern char *get_func_name(Oid funcid);
 extern Oid	get_func_rettype(Oid funcid);
+extern bool	get_func_retset(Oid funcid);
 extern char func_volatile(Oid funcid);
 extern Oid	get_relname_relid(const char *relname, Oid relnamespace);
 extern char *get_rel_name(Oid relid);