From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 1 Mar 2007 18:51:03 +0000 (+0000)
Subject: Fix markQueryForLocking() to work correctly in the presence of nested views.
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=5e67cf4513848df45173313fec296fd5c4d96248;p=users%2Fbernd%2Fpostgres.git

Fix markQueryForLocking() to work correctly in the presence of nested views.
It has been wrong for this case since it was first written for 7.1 :-(
Per report from Pavel Hanák.
---

diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index 0cc4fc99c2..2bc345abde 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -42,7 +42,7 @@ static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index);
 static void rewriteTargetList(Query *parsetree, Relation target_relation);
 static TargetEntry *process_matched_tle(TargetEntry *src_tle,
 					TargetEntry *prior_tle);
-static void markQueryForUpdate(Query *qry, bool skipOldNew);
+static void markQueryForUpdate(Query *qry, Node *jtnode);
 static List *matchLocks(CmdType event, RuleLock *rulelocks,
 		   int varno, Query *parsetree);
 static Query *fireRIRrules(Query *parsetree);
@@ -604,7 +604,7 @@ ApplyRetrieveRule(Query *parsetree,
 		/*
 		 * Set up the view's referenced tables as if FOR UPDATE.
 		 */
-		markQueryForUpdate(rule_action, true);
+		markQueryForUpdate(rule_action, (Node *) rule_action->jointree);
 	}
 
 	return parsetree;
@@ -617,23 +617,19 @@ ApplyRetrieveRule(Query *parsetree,
  * aggregate.  We leave it to the planner to detect that.
  *
  * NB: this must agree with the parser's transformForUpdate() routine.
+ * However, unlike the parser we have to be careful not to mark a view's
+ * OLD and NEW rels for updating.  The best way to handle that seems to be
+ * to scan the jointree to determine which rels are used.
  */
 static void
-markQueryForUpdate(Query *qry, bool skipOldNew)
+markQueryForUpdate(Query *qry, Node *jtnode)
 {
-	Index		rti = 0;
-	List	   *l;
-
-	foreach(l, qry->rtable)
+	if (jtnode == NULL)
+		return;
+	if (IsA(jtnode, RangeTblRef))
 	{
-		RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
-
-		rti++;
-
-		/* Ignore OLD and NEW entries if we are at top level of view */
-		if (skipOldNew &&
-			(rti == PRS2_OLD_VARNO || rti == PRS2_NEW_VARNO))
-			continue;
+		int			rti = ((RangeTblRef *) jtnode)->rtindex;
+		RangeTblEntry *rte = rt_fetch(rti, qry->rtable);
 
 		if (rte->rtekind == RTE_RELATION)
 		{
@@ -644,9 +640,27 @@ markQueryForUpdate(Query *qry, bool skipOldNew)
 		else if (rte->rtekind == RTE_SUBQUERY)
 		{
 			/* FOR UPDATE of subquery is propagated to subquery's rels */
-			markQueryForUpdate(rte->subquery, false);
+			markQueryForUpdate(rte->subquery, (Node *) rte->subquery->jointree);
 		}
 	}
+	else if (IsA(jtnode, FromExpr))
+	{
+		FromExpr   *f = (FromExpr *) jtnode;
+		List	   *l;
+
+		foreach(l, f->fromlist)
+			markQueryForUpdate(qry, lfirst(l));
+	}
+	else if (IsA(jtnode, JoinExpr))
+	{
+		JoinExpr   *j = (JoinExpr *) jtnode;
+
+		markQueryForUpdate(qry, j->larg);
+		markQueryForUpdate(qry, j->rarg);
+	}
+	else
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(jtnode));
 }