From 0e952cdb9029cf6f8a574f4d888cbb134e646d0e Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 21 Dec 2000 17:36:15 +0000
Subject: [PATCH] Fix longstanding bug with VIEW using BETWEEN: OffsetVarNodes
would get applied to the duplicated subtree twice. Probably someday we
should fix the parser not to generate multiple links to the same subtree, but
for now a quick copyObject() is the path of least resistance.
---
src/backend/commands/view.c | 57 +++++++++++++++++++------------------
1 file changed, 29 insertions(+), 28 deletions(-)
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 2262d4bd508..0f726e8e6e0 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $Id: view.c,v 1.50 2000/10/26 17:04:12 tgl Exp $
+ * $Id: view.c,v 1.51 2000/12/21 17:36:15 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -156,12 +156,12 @@ FormViewRetrieveRule(char *viewName, Query *viewParse)
static void
DefineViewRules(char *viewName, Query *viewParse)
{
- RuleStmt *retrieve_rule = NULL;
+ RuleStmt *retrieve_rule;
#ifdef NOTYET
- RuleStmt *replace_rule = NULL;
- RuleStmt *append_rule = NULL;
- RuleStmt *delete_rule = NULL;
+ RuleStmt *replace_rule;
+ RuleStmt *append_rule;
+ RuleStmt *delete_rule;
#endif
@@ -198,16 +198,11 @@ DefineViewRules(char *viewName, Query *viewParse)
* Of course we must also increase the 'varnos' of all the Var nodes
* by 2...
*
- * These extra RT entries are not actually used in the query, obviously.
- * We add them so that views look the same as ON SELECT rules ---
- * the rule rewriter assumes that ALL rules have OLD and NEW RTEs.
- *
- * NOTE: these are destructive changes. It would be difficult to
- * make a complete copy of the parse tree and make the changes
- * in the copy.
+ * These extra RT entries are not actually used in the query,
+ * except for run-time permission checking.
*---------------------------------------------------------------
*/
-static void
+static Query *
UpdateRangeTableOfViewParse(char *viewName, Query *viewParse)
{
List *new_rt;
@@ -215,7 +210,17 @@ UpdateRangeTableOfViewParse(char *viewName, Query *viewParse)
*rt_entry2;
/*
- * create the 2 new range table entries and form the new range
+ * Make a copy of the given parsetree. It's not so much that we
+ * don't want to scribble on our input, it's that the parser has
+ * a bad habit of outputting multiple links to the same subtree
+ * for constructs like BETWEEN, and we mustn't have OffsetVarNodes
+ * increment the varno of a Var node twice. copyObject will expand
+ * any multiply-referenced subtree into multiple copies.
+ */
+ viewParse = (Query *) copyObject(viewParse);
+
+ /*
+ * Create the 2 new range table entries and form the new range
* table... OLD first, then NEW....
*/
rt_entry1 = addRangeTableEntry(NULL, viewName,
@@ -230,16 +235,14 @@ UpdateRangeTableOfViewParse(char *viewName, Query *viewParse)
new_rt = lcons(rt_entry1, lcons(rt_entry2, viewParse->rtable));
- /*
- * Now the tricky part.... Update the range table in place... Be
- * careful here, or hell breaks loooooooooooooOOOOOOOOOOOOOOOOOOSE!
- */
viewParse->rtable = new_rt;
/*
- * now offset all var nodes by 2, and jointree RT indexes too.
+ * Now offset all var nodes by 2, and jointree RT indexes too.
*/
OffsetVarNodes((Node *) viewParse, 2, 0);
+
+ return viewParse;
}
/*-------------------------------------------------------------------
@@ -257,15 +260,11 @@ UpdateRangeTableOfViewParse(char *viewName, Query *viewParse)
void
DefineView(char *viewName, Query *viewParse)
{
- List *viewTlist;
-
- viewTlist = viewParse->targetList;
-
/*
* Create the "view" relation NOTE: if it already exists, the xact
* will be aborted.
*/
- DefineVirtualRelation(viewName, viewTlist);
+ DefineVirtualRelation(viewName, viewParse->targetList);
/*
* The relation we have just created is not visible to any other
@@ -276,11 +275,13 @@ DefineView(char *viewName, Query *viewParse)
/*
* The range table of 'viewParse' does not contain entries for the
- * "OLD" and "NEW" relations. So... add them! NOTE: we make the
- * update in place! After this call 'viewParse' will never be what it
- * used to be...
+ * "OLD" and "NEW" relations. So... add them!
+ */
+ viewParse = UpdateRangeTableOfViewParse(viewName, viewParse);
+
+ /*
+ * Now create the rules associated with the view.
*/
- UpdateRangeTableOfViewParse(viewName, viewParse);
DefineViewRules(viewName, viewParse);
}
--
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