Reimplementation of UNION/INTERSECT/EXCEPT. INTERSECT/EXCEPT now meet the

SQL92 semantics, including support for ALL option.  All three can be used
in subqueries and views.  DISTINCT and ORDER BY work now in views, too.
This rewrite fixes many problems with cross-datatype UNIONs and INSERT/SELECT
where the SELECT yields different datatypes than the INSERT needs.  I did
that by making UNION subqueries and SELECT in INSERT be treated like
subselects-in-FROM, thereby allowing an extra level of targetlist where the
datatype conversions can be inserted safely.
INITDB NEEDED!

1 files changed, 25 insertions, 38 deletions

diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 182d1384aa1..03e38371df5 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.42 2000/09/29 18:21:33 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.43 2000/10/05 19:11:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -29,7 +29,8 @@
 Index		PlannerQueryLevel;	/* level of current query */
 List	   *PlannerInitPlan;	/* init subplans for current query */
 List	   *PlannerParamVar;	/* to get Var from Param->paramid */
-int			PlannerPlanId;		/* to assign unique ID to subquery plans */
+
+int			PlannerPlanId = 0;	/* to assign unique ID to subquery plans */
 
 /*--------------------
  * PlannerParamVar is a list of Var nodes, wherein the n'th entry
@@ -81,7 +82,7 @@ replace_var(Var *var)
 
 	/*
 	 * If there's already a PlannerParamVar entry for this same Var, just
-	 * use it.	NOTE: in situations involving UNION or inheritance, it is
+	 * use it.	NOTE: in sufficiently complex querytrees, it is
 	 * possible for the same varno/varlevel to refer to different RTEs in
 	 * different parts of the parsetree, so that different fields might
 	 * end up sharing the same Param number.  As long as we check the
@@ -128,11 +129,6 @@ make_subplan(SubLink *slink)
 	Plan	   *plan;
 	List	   *lst;
 	Node	   *result;
-	List	   *saved_ip = PlannerInitPlan;
-
-	PlannerInitPlan = NULL;
-
-	PlannerQueryLevel++;		/* we become child */
 
 	/*
 	 * Check to see if this node was already processed; if so we have
@@ -181,45 +177,30 @@ make_subplan(SubLink *slink)
 	else
 		tuple_fraction = -1.0;	/* default behavior */
 
-	node->plan = plan = subquery_planner(subquery, tuple_fraction);
-
 	/*
-	 * Assign subPlan, extParam and locParam to plan nodes. At the moment,
-	 * SS_finalize_plan doesn't handle initPlan-s and so we assign them to
-	 * the topmost plan node and take care about its extParam too.
+	 * Generate the plan for the subquery.
 	 */
-	(void) SS_finalize_plan(plan);
-	plan->initPlan = PlannerInitPlan;
-
-	/* Create extParam list as union of InitPlan-s' lists */
-	foreach(lst, PlannerInitPlan)
-	{
-		List	   *lp;
-
-		foreach(lp, ((SubPlan *) lfirst(lst))->plan->extParam)
-		{
-			if (!intMember(lfirsti(lp), plan->extParam))
-				plan->extParam = lappendi(plan->extParam, lfirsti(lp));
-		}
-	}
+	node->plan = plan = subquery_planner(subquery, tuple_fraction);
 
-	/* and now we are parent again */
-	PlannerInitPlan = saved_ip;
-	PlannerQueryLevel--;
+	node->plan_id = PlannerPlanId++; /* Assign unique ID to this SubPlan */
 
-	node->plan_id = PlannerPlanId++;
 	node->rtable = subquery->rtable;
 	node->sublink = slink;
+
 	slink->subselect = NULL;	/* cool ?! see error check above! */
 
-	/* make parParam list of params coming from current query level */
+	/*
+	 * Make parParam list of params that current query level will pass
+	 * to this child plan.
+	 */
 	foreach(lst, plan->extParam)
 	{
-		Var		   *var = nth(lfirsti(lst), PlannerParamVar);
+		int			paramid = lfirsti(lst);
+		Var		   *var = nth(paramid, PlannerParamVar);
 
 		/* note varlevelsup is absolute level number */
 		if (var->varlevelsup == PlannerQueryLevel)
-			node->parParam = lappendi(node->parParam, lfirsti(lst));
+			node->parParam = lappendi(node->parParam, paramid);
 	}
 
 	/*
@@ -625,6 +606,11 @@ SS_finalize_plan(Plan *plan)
 								 SS_finalize_plan((Plan *) lfirst(lst)));
 			break;
 
+		case T_SubqueryScan:
+			results.paramids = set_unioni(results.paramids,
+						SS_finalize_plan(((SubqueryScan *) plan)->subplan));
+			break;
+
 		case T_IndexScan:
 			finalize_primnode((Node *) ((IndexScan *) plan)->indxqual,
 							  &results);
@@ -667,10 +653,10 @@ SS_finalize_plan(Plan *plan)
 
 		case T_Agg:
 		case T_SeqScan:
-		case T_SubqueryScan:
 		case T_Material:
 		case T_Sort:
 		case T_Unique:
+		case T_SetOp:
 		case T_Group:
 			break;
 
@@ -689,17 +675,18 @@ SS_finalize_plan(Plan *plan)
 
 	foreach(lst, results.paramids)
 	{
-		Var		   *var = nth(lfirsti(lst), PlannerParamVar);
+		int			paramid = lfirsti(lst);
+		Var		   *var = nth(paramid, PlannerParamVar);
 
 		/* note varlevelsup is absolute level number */
 		if (var->varlevelsup < PlannerQueryLevel)
-			extParam = lappendi(extParam, lfirsti(lst));
+			extParam = lappendi(extParam, paramid);
 		else if (var->varlevelsup > PlannerQueryLevel)
 			elog(ERROR, "SS_finalize_plan: plan shouldn't reference subplan's variable");
 		else
 		{
 			Assert(var->varno == 0 && var->varattno == 0);
-			locParam = lappendi(locParam, lfirsti(lst));
+			locParam = lappendi(locParam, paramid);
 		}
 	}