Restructure representation of join alias variables. An explicit JOIN

now has an RTE of its own, and references to its outputs now are Vars
referencing the JOIN RTE, rather than CASE-expressions.  This allows
reverse-listing in ruleutils.c to use the correct alias easily, rather
than painfully reverse-engineering the alias namespace as it used to do.
Also, nested FULL JOINs work correctly, because the result of the inner
joins are simple Vars that the planner can cope with.  This fixes a bug
reported a couple times now, notably by Tatsuo on 18-Nov-01.  The alias
Vars are expanded into COALESCE expressions where needed at the very end
of planning, rather than during parsing.
Also, beginnings of support for showing plan qualifier expressions in
EXPLAIN.  There are probably still cases that need work.
initdb forced due to change of stored-rule representation.

1 files changed, 17 insertions, 9 deletions

diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index f3e2306a00b..e118654e404 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.98 2001/10/25 05:49:41 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.99 2002/03/12 00:51:58 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -289,6 +289,7 @@ ApplyRetrieveRule(Query *parsetree,
 	 */
 	rte = rt_fetch(rt_index, parsetree->rtable);
 
+	rte->rtekind = RTE_SUBQUERY;
 	rte->relname = NULL;
 	rte->relid = InvalidOid;
 	rte->subquery = rule_action;
@@ -354,17 +355,17 @@ markQueryForUpdate(Query *qry, bool skipOldNew)
 			(rti == PRS2_OLD_VARNO || rti == PRS2_NEW_VARNO))
 			continue;
 
-		if (rte->subquery)
-		{
-			/* FOR UPDATE of subquery is propagated to subquery's rels */
-			markQueryForUpdate(rte->subquery, false);
-		}
-		else
+		if (rte->rtekind == RTE_RELATION)
 		{
 			if (!intMember(rti, qry->rowMarks))
 				qry->rowMarks = lappendi(qry->rowMarks, rti);
 			rte->checkForWrite = true;
 		}
+		else if (rte->rtekind == RTE_SUBQUERY)
+		{
+			/* FOR UPDATE of subquery is propagated to subquery's rels */
+			markQueryForUpdate(rte->subquery, false);
+		}
 	}
 }
 
@@ -440,13 +441,19 @@ fireRIRrules(Query *parsetree)
 		 * to do to this level of the query, but we must recurse into the
 		 * subquery to expand any rule references in it.
 		 */
-		if (rte->subquery)
+		if (rte->rtekind == RTE_SUBQUERY)
 		{
 			rte->subquery = fireRIRrules(rte->subquery);
 			continue;
 		}
 
 		/*
+		 * Joins and other non-relation RTEs can be ignored completely.
+		 */
+		if (rte->rtekind != RTE_RELATION)
+			continue;
+
+		/*
 		 * If the table is not referenced in the query, then we ignore it.
 		 * This prevents infinite expansion loop due to new rtable entries
 		 * inserted by expansion of a rule. A table is referenced if it is
@@ -756,6 +763,7 @@ RewriteQuery(Query *parsetree, bool *instead_flag, List **qual_products)
 	result_relation = parsetree->resultRelation;
 	Assert(result_relation != 0);
 	rt_entry = rt_fetch(result_relation, parsetree->rtable);
+	Assert(rt_entry->rtekind == RTE_RELATION);
 
 	/*
 	 * This may well be the first access to the result relation during the
@@ -945,7 +953,7 @@ QueryRewrite(Query *parsetree)
 			RangeTblEntry *rte = rt_fetch(query->resultRelation,
 										  query->rtable);
 
-			if (rte->subquery)
+			if (rte->rtekind == RTE_SUBQUERY)
 			{
 				switch (query->commandType)
 				{