From 84666801ed0e787e8b373c6eee18553b27aa574c Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 25 Feb 2003 23:47:43 +0000
Subject: [PATCH] Remove REWRITE_INVOKE_MAX in favor of making an accurate
check for recursion in RewriteQuery(); also, detect recursion in
fireRIRrules(), so as to catch self-referential views per example from Ryan
VanderBijl. Minor code restructuring to make it easier to catch recursive
case.
---
src/backend/rewrite/rewriteHandler.c | 268 +++++++++++++--------------
1 file changed, 128 insertions(+), 140 deletions(-)
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index 916c4d4c3f3..e39ee0efbe7 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 1.117 2003/02/13 21:39:50 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.118 2003/02/25 23:47:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -33,6 +33,12 @@
#include "utils/lsyscache.h"
+/* We use a list of these to detect recursion in RewriteQuery */
+typedef struct rewrite_event {
+ Oid relation; /* OID of relation having rules */
+ CmdType event; /* type of rule being fired */
+} rewrite_event;
+
static Query *rewriteRuleAction(Query *parsetree,
Query *rule_action,
Node *rule_qual,
@@ -45,7 +51,7 @@ static TargetEntry *process_matched_tle(TargetEntry *src_tle,
static void markQueryForUpdate(Query *qry, bool skipOldNew);
static List *matchLocks(CmdType event, RuleLock *rulelocks,
int varno, Query *parsetree);
-static Query *fireRIRrules(Query *parsetree);
+static Query *fireRIRrules(Query *parsetree, List *activeRIRs);
/*
@@ -526,8 +532,8 @@ matchLocks(CmdType event,
int nlocks;
int i;
- Assert(rulelocks != NULL); /* we get called iff there is some lock */
- Assert(parsetree != NULL);
+ if (rulelocks == NULL)
+ return NIL;
if (parsetree->commandType != CMD_SELECT)
{
@@ -562,7 +568,8 @@ ApplyRetrieveRule(Query *parsetree,
int rt_index,
bool relation_level,
Relation relation,
- bool relIsUsed)
+ bool relIsUsed,
+ List *activeRIRs)
{
Query *rule_action;
RangeTblEntry *rte,
@@ -581,7 +588,7 @@ ApplyRetrieveRule(Query *parsetree,
*/
rule_action = copyObject(lfirst(rule->actions));
- rule_action = fireRIRrules(rule_action);
+ rule_action = fireRIRrules(rule_action, activeRIRs);
/*
* VIEWs are really easy --- just plug the view query in as a
@@ -683,7 +690,7 @@ markQueryForUpdate(Query *qry, bool skipOldNew)
* the SubLink's subselect link with the possibly-rewritten subquery.
*/
static bool
-fireRIRonSubLink(Node *node, void *context)
+fireRIRonSubLink(Node *node, List *activeRIRs)
{
if (node == NULL)
return false;
@@ -692,7 +699,8 @@ fireRIRonSubLink(Node *node, void *context)
SubLink *sub = (SubLink *) node;
/* Do what we came for */
- sub->subselect = (Node *) fireRIRrules((Query *) (sub->subselect));
+ sub->subselect = (Node *) fireRIRrules((Query *) sub->subselect,
+ activeRIRs);
/* Fall through to process lefthand args of SubLink */
}
@@ -701,7 +709,7 @@ fireRIRonSubLink(Node *node, void *context)
* processed subselects of subselects for us.
*/
return expression_tree_walker(node, fireRIRonSubLink,
- (void *) context);
+ (void *) activeRIRs);
}
@@ -710,7 +718,7 @@ fireRIRonSubLink(Node *node, void *context)
* Apply all RIR rules on each rangetable entry in a query
*/
static Query *
-fireRIRrules(Query *parsetree)
+fireRIRrules(Query *parsetree, List *activeRIRs)
{
int rt_index;
@@ -729,7 +737,6 @@ fireRIRrules(Query *parsetree)
LOCKMODE lockmode;
bool relIsUsed;
int i;
- List *l;
++rt_index;
@@ -742,7 +749,7 @@ fireRIRrules(Query *parsetree)
*/
if (rte->rtekind == RTE_SUBQUERY)
{
- rte->subquery = fireRIRrules(rte->subquery);
+ rte->subquery = fireRIRrules(rte->subquery, activeRIRs);
continue;
}
@@ -814,18 +821,30 @@ fireRIRrules(Query *parsetree)
}
/*
- * Now apply them
+ * If we found any, apply them --- but first check for recursion!
*/
- foreach(l, locks)
+ if (locks != NIL)
{
- rule = lfirst(l);
-
- parsetree = ApplyRetrieveRule(parsetree,
- rule,
- rt_index,
- rule->attrno == -1,
- rel,
- relIsUsed);
+ List *newActiveRIRs;
+ List *l;
+
+ if (oidMember(RelationGetRelid(rel), activeRIRs))
+ elog(ERROR, "Infinite recursion detected in rules for relation %s",
+ RelationGetRelationName(rel));
+ newActiveRIRs = lconso(RelationGetRelid(rel), activeRIRs);
+
+ foreach(l, locks)
+ {
+ rule = lfirst(l);
+
+ parsetree = ApplyRetrieveRule(parsetree,
+ rule,
+ rt_index,
+ rule->attrno == -1,
+ rel,
+ relIsUsed,
+ newActiveRIRs);
+ }
}
heap_close(rel, NoLock);
@@ -836,7 +855,7 @@ fireRIRrules(Query *parsetree)
* in the rtable.
*/
if (parsetree->hasSubLinks)
- query_tree_walker(parsetree, fireRIRonSubLink, NULL,
+ query_tree_walker(parsetree, fireRIRonSubLink, (void *) activeRIRs,
QTW_IGNORE_RT_SUBQUERIES);
/*
@@ -967,7 +986,7 @@ fireRules(Query *parsetree,
* its actions only in cases where the rule quals of all
* INSTEAD rules are false. Think of it as the default action
* in a case. We save this in *qual_product so
- * deepRewriteQuery() can add it to the query list after we
+ * RewriteQuery() can add it to the query list after we
* mangled it up enough.
*
* If we have already found an unqualified INSTEAD rule,
@@ -1006,124 +1025,109 @@ fireRules(Query *parsetree,
/*
- * One pass of rewriting a single query.
+ * RewriteQuery -
+ * rewrites the query and apply the rules again on the queries rewritten
*
- * parsetree is the input query. Return value and output parameters
- * are defined the same as for fireRules, above.
+ * rewrite_events is a list of open query-rewrite actions, so we can detect
+ * infinite recursion.
*/
static List *
-RewriteQuery(Query *parsetree, bool *instead_flag, Query **qual_product)
+RewriteQuery(Query *parsetree, List *rewrite_events)
{
- CmdType event;
- List *product_queries = NIL;
- int result_relation;
- RangeTblEntry *rt_entry;
- Relation rt_entry_relation;
- RuleLock *rt_entry_locks;
-
- Assert(parsetree != NULL);
-
- event = parsetree->commandType;
+ CmdType event = parsetree->commandType;
+ bool instead = false;
+ Query *qual_product = NULL;
+ List *rewritten = NIL;
/*
+ * If the statement is an update, insert or delete - fire rules on it.
+ *
* SELECT rules are handled later when we have all the queries that
- * should get executed
- */
- if (event == CMD_SELECT)
- return NIL;
-
- /*
- * Utilities aren't rewritten at all - why is this here?
- */
- if (event == CMD_UTILITY)
- return NIL;
-
- /*
- * the statement is an update, insert or delete - fire rules on it.
- */
- 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
- * current statement (it will be, if this Query was extracted from a
- * rule or somehow got here other than via the parser). Therefore,
- * grab the appropriate lock type for a result relation, and do not
- * release it until end of transaction. This protects the rewriter
- * and planner against schema changes mid-query.
- */
- rt_entry_relation = heap_open(rt_entry->relid, RowExclusiveLock);
-
- /*
- * If it's an INSERT or UPDATE, rewrite the targetlist into standard
- * form. This will be needed by the planner anyway, and doing it now
- * ensures that any references to NEW.field will behave sanely.
+ * should get executed. Also, utilities aren't rewritten at all
+ * (do we still need that check?)
*/
- if (event == CMD_INSERT || event == CMD_UPDATE)
- rewriteTargetList(parsetree, rt_entry_relation);
+ if (event != CMD_SELECT && event != CMD_UTILITY)
+ {
+ int result_relation;
+ RangeTblEntry *rt_entry;
+ Relation rt_entry_relation;
+ List *locks;
- /*
- * Collect and apply the appropriate rules.
- */
- rt_entry_locks = rt_entry_relation->rd_rules;
+ result_relation = parsetree->resultRelation;
+ Assert(result_relation != 0);
+ rt_entry = rt_fetch(result_relation, parsetree->rtable);
+ Assert(rt_entry->rtekind == RTE_RELATION);
- if (rt_entry_locks != NULL)
- {
- List *locks = matchLocks(event, rt_entry_locks,
- result_relation, parsetree);
-
- product_queries = fireRules(parsetree,
- result_relation,
- event,
- locks,
- instead_flag,
- qual_product);
- }
+ /*
+ * This may well be the first access to the result relation during the
+ * current statement (it will be, if this Query was extracted from a
+ * rule or somehow got here other than via the parser). Therefore,
+ * grab the appropriate lock type for a result relation, and do not
+ * release it until end of transaction. This protects the rewriter
+ * and planner against schema changes mid-query.
+ */
+ rt_entry_relation = heap_open(rt_entry->relid, RowExclusiveLock);
- heap_close(rt_entry_relation, NoLock); /* keep lock! */
+ /*
+ * If it's an INSERT or UPDATE, rewrite the targetlist into standard
+ * form. This will be needed by the planner anyway, and doing it now
+ * ensures that any references to NEW.field will behave sanely.
+ */
+ if (event == CMD_INSERT || event == CMD_UPDATE)
+ rewriteTargetList(parsetree, rt_entry_relation);
- return product_queries;
-}
+ /*
+ * Collect and apply the appropriate rules.
+ */
+ locks = matchLocks(event, rt_entry_relation->rd_rules,
+ result_relation, parsetree);
+ if (locks != NIL)
+ {
+ List *product_queries;
-/*
- * to avoid infinite recursion, we restrict the number of times a query
- * can be rewritten. Detecting cycles is left for the reader as an exercise.
- */
-#ifndef REWRITE_INVOKE_MAX
-#define REWRITE_INVOKE_MAX 100
-#endif
+ product_queries = fireRules(parsetree,
+ result_relation,
+ event,
+ locks,
+ &instead,
+ &qual_product);
-static int numQueryRewriteInvoked = 0;
+ /*
+ * If we got any product queries, recursively rewrite them
+ * --- but first check for recursion!
+ */
+ if (product_queries != NIL)
+ {
+ List *n;
+ rewrite_event *rev;
-/*
- * deepRewriteQuery -
- * rewrites the query and apply the rules again on the queries rewritten
- */
-static List *
-deepRewriteQuery(Query *parsetree)
-{
- List *rewritten = NIL;
- List *result;
- bool instead = false;
- Query *qual_product = NULL;
- List *n;
+ foreach(n, rewrite_events)
+ {
+ rev = (rewrite_event *) lfirst(n);
+ if (rev->relation == RelationGetRelid(rt_entry_relation) &&
+ rev->event == event)
+ elog(ERROR, "Infinite recursion detected in rules for relation %s",
+ RelationGetRelationName(rt_entry_relation));
+ }
- if (++numQueryRewriteInvoked > REWRITE_INVOKE_MAX)
- elog(ERROR, "query rewritten %d times, may contain cycles",
- numQueryRewriteInvoked - 1);
+ rev = (rewrite_event *) palloc(sizeof(rewrite_event));
+ rev->relation = RelationGetRelid(rt_entry_relation);
+ rev->event = event;
+ rewrite_events = lcons(rev, rewrite_events);
- result = RewriteQuery(parsetree, &instead, &qual_product);
+ foreach(n, product_queries)
+ {
+ Query *pt = (Query *) lfirst(n);
+ List *newstuff;
- foreach(n, result)
- {
- Query *pt = lfirst(n);
- List *newstuff;
+ newstuff = RewriteQuery(pt, rewrite_events);
+ rewritten = nconc(rewritten, newstuff);
+ }
+ }
+ }
- newstuff = deepRewriteQuery(pt);
- rewritten = nconc(rewritten, newstuff);
+ heap_close(rt_entry_relation, NoLock); /* keep lock! */
}
/*
@@ -1161,22 +1165,6 @@ deepRewriteQuery(Query *parsetree)
}
-/*
- * QueryRewriteOne -
- * rewrite one query
- */
-static List *
-QueryRewriteOne(Query *parsetree)
-{
- numQueryRewriteInvoked = 0;
-
- /*
- * take a deep breath and apply all the rewrite rules - ay
- */
- return deepRewriteQuery(parsetree);
-}
-
-
/*
* QueryRewrite -
* Primary entry point to the query rewriter.
@@ -1198,7 +1186,7 @@ QueryRewrite(Query *parsetree)
*
* Apply all non-SELECT rules possibly getting 0 or many queries
*/
- querylist = QueryRewriteOne(parsetree);
+ querylist = RewriteQuery(parsetree, NIL);
/*
* Step 2
@@ -1209,7 +1197,7 @@ QueryRewrite(Query *parsetree)
{
Query *query = (Query *) lfirst(l);
- query = fireRIRrules(query);
+ query = fireRIRrules(query, NIL);
/*
* If the query target was rewritten as a view, complain.
--
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