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Back-patch the 8.3 fix that prohibits TRUNCATE, CLUSTER, and REINDEX when the

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current transaction has any open references to the target relation or index
(implying it has an active query using the relation).  Also back-patch the
8.2 fix that prohibits TRUNCATE and CLUSTER when there are pending
AFTER-trigger events.  Per suggestion from Heikki.
REL8_2_STABLE
Tom Lane 18 years ago
parent 8eecf95d41
commit 35b6007efe
6 changed files with 113 additions and 74 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 19
      src/backend/catalog/index.c
  2. 9
      src/backend/commands/cluster.c
  3. 108
      src/backend/commands/tablecmds.c
  4. 43
      src/backend/commands/trigger.c
  5. 4
      src/include/commands/tablecmds.h
  6. 4
      src/include/commands/trigger.h

19
src/backend/catalog/index.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/catalog/index.c,v 1.274.2.2 2008/01/03 21:23:45 tgl Exp $
* $PostgreSQL: pgsql/src/backend/catalog/index.c,v 1.274.2.3 2008/05/27 21:13:25 tgl Exp $
*
*
* INTERFACE ROUTINES
@ -33,10 +33,12 @@
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_type.h"
#include "commands/tablecmds.h"
#include "executor/executor.h"
#include "miscadmin.h"
#include "optimizer/clauses.h"
@ -1954,6 +1956,21 @@ reindex_index(Oid indexId)
*/
iRel = index_open(indexId, AccessExclusiveLock);
/*
* Don't allow reindex on temp tables of other backends ... their local
* buffer manager is not going to cope.
*/
if (isOtherTempNamespace(RelationGetNamespace(iRel)))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot reindex temporary tables of other sessions")));
/*
* Also check for active uses of the index in the current transaction;
* we don't want to reindex underneath an open indexscan.
*/
CheckTableNotInUse(iRel, "REINDEX INDEX");
/*
* If it's a shared index, we must do inplace processing (because we have
* no way to update relfilenode in other databases). Otherwise we can do

9
src/backend/commands/cluster.c
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@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.154.2.2 2007/09/29 18:05:28 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.154.2.3 2008/05/27 21:13:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -28,6 +28,7 @@
#include "catalog/namespace.h"
#include "catalog/toasting.h"
#include "commands/cluster.h"
#include "commands/tablecmds.h"
#include "miscadmin.h"
#include "utils/acl.h"
#include "utils/fmgroids.h"
@ -449,6 +450,12 @@ check_index_is_clusterable(Relation OldHeap, Oid indexOid, bool recheck)
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot cluster temporary tables of other sessions")));
/*
* Also check for active uses of the relation in the current transaction,
* including open scans and pending AFTER trigger events.
*/
CheckTableNotInUse(OldHeap, "CLUSTER");
/* Drop relcache refcnt on OldIndex, but keep lock */
index_close(OldIndex, NoLock);
}

108
src/backend/commands/tablecmds.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.206.2.5 2008/05/09 22:37:41 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.206.2.6 2008/05/27 21:13:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -596,13 +596,6 @@ ExecuteTruncate(TruncateStmt *stmt)
heap_truncate_check_FKs(rels, false);
#endif
/*
* Also check for pending AFTER trigger events on the target relations. We
* can't just leave those be, since they will try to fetch tuples that the
* TRUNCATE removes.
*/
AfterTriggerCheckTruncate(relids);
/*
* OK, truncate each table.
*/
@ -683,6 +676,12 @@ truncate_check_rel(Relation rel)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot truncate temporary tables of other sessions")));
/*
* Also check for active uses of the relation in the current transaction,
* including open scans and pending AFTER trigger events.
*/
CheckTableNotInUse(rel, "TRUNCATE");
}
/*----------
@ -1912,6 +1911,55 @@ update_ri_trigger_args(Oid relid,
CommandCounterIncrement();
}
/*
* Disallow ALTER TABLE (and similar commands) when the current backend has
* any open reference to the target table besides the one just acquired by
* the calling command; this implies there's an open cursor or active plan.
* We need this check because our AccessExclusiveLock doesn't protect us
* against stomping on our own foot, only other people's feet!
*
* For ALTER TABLE, the only case known to cause serious trouble is ALTER
* COLUMN TYPE, and some changes are obviously pretty benign, so this could
* possibly be relaxed to only error out for certain types of alterations.
* But the use-case for allowing any of these things is not obvious, so we
* won't work hard at it for now.
*
* We also reject these commands if there are any pending AFTER trigger events
* for the rel. This is certainly necessary for the rewriting variants of
* ALTER TABLE, because they don't preserve tuple TIDs and so the pending
* events would try to fetch the wrong tuples. It might be overly cautious
* in other cases, but again it seems better to err on the side of paranoia.
*
* REINDEX calls this with "rel" referencing the index to be rebuilt; here
* we are worried about active indexscans on the index. The trigger-event
* check can be skipped, since we are doing no damage to the parent table.
*
* The statement name (eg, "ALTER TABLE") is passed for use in error messages.
*/
void
CheckTableNotInUse(Relation rel, const char *stmt)
{
int expected_refcnt;
expected_refcnt = rel->rd_isnailed ? 2 : 1;
if (rel->rd_refcnt != expected_refcnt)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_IN_USE),
/* translator: first %s is a SQL command, eg ALTER TABLE */
errmsg("cannot %s \"%s\" because "
"it is being used by active queries in this session",
stmt, RelationGetRelationName(rel))));
if (rel->rd_rel->relkind != RELKIND_INDEX &&
AfterTriggerPendingOnRel(RelationGetRelid(rel)))
ereport(ERROR,
(errcode(ERRCODE_OBJECT_IN_USE),
/* translator: first %s is a SQL command, eg ALTER TABLE */
errmsg("cannot %s \"%s\" because "
"it has pending trigger events",
stmt, RelationGetRelationName(rel))));
}
/*
* AlterTable
* Execute ALTER TABLE, which can be a list of subcommands
@ -1949,26 +1997,8 @@ void
AlterTable(AlterTableStmt *stmt)
{
Relation rel = relation_openrv(stmt->relation, AccessExclusiveLock);
int expected_refcnt;
/*
* Disallow ALTER TABLE when the current backend has any open reference
* to it besides the one we just got (such as an open cursor or active
* plan); our AccessExclusiveLock doesn't protect us against stomping on
* our own foot, only other people's feet!
*
* Note: the only case known to cause serious trouble is ALTER COLUMN TYPE,
* and some changes are obviously pretty benign, so this could possibly
* be relaxed to only error out for certain types of alterations. But
* the use-case for allowing any of these things is not obvious, so we
* won't work hard at it for now.
*/
expected_refcnt = rel->rd_isnailed ? 2 : 1;
if (rel->rd_refcnt != expected_refcnt)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_IN_USE),
errmsg("relation \"%s\" is being used by active queries in this session",
RelationGetRelationName(rel))));
CheckTableNotInUse(rel, "ALTER TABLE");
ATController(rel, stmt->cmds, interpretInhOption(stmt->relation->inhOpt));
}
@ -1981,7 +2011,8 @@ AlterTable(AlterTableStmt *stmt)
* We do not reject if the relation is already open, because it's quite
* likely that one or more layers of caller have it open. That means it
* is unsafe to use this entry point for alterations that could break
* existing query plans.
* existing query plans. On the assumption it's not used for such, we
* don't have to reject pending AFTER triggers, either.
*/
void
AlterTableInternal(Oid relid, List *cmds, bool recurse)
@ -2939,12 +2970,7 @@ ATSimpleRecursion(List **wqueue, Relation rel,
if (childrelid == relid)
continue;
childrel = relation_open(childrelid, AccessExclusiveLock);
/* check for child relation in use in this session */
if (childrel->rd_refcnt != 1)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_IN_USE),
errmsg("relation \"%s\" is being used by active queries in this session",
RelationGetRelationName(childrel))));
CheckTableNotInUse(childrel, "ALTER TABLE");
ATPrepCmd(wqueue, childrel, cmd, false, true);
relation_close(childrel, NoLock);
}
@ -2976,12 +3002,7 @@ ATOneLevelRecursion(List **wqueue, Relation rel,
Relation childrel;
childrel = relation_open(childrelid, AccessExclusiveLock);
/* check for child relation in use in this session */
if (childrel->rd_refcnt != 1)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_IN_USE),
errmsg("relation \"%s\" is being used by active queries in this session",
RelationGetRelationName(childrel))));
CheckTableNotInUse(childrel, "ALTER TABLE");
ATPrepCmd(wqueue, childrel, cmd, true, true);
relation_close(childrel, NoLock);
}
@ -3799,12 +3820,7 @@ ATExecDropColumn(Relation rel, const char *colName,
Form_pg_attribute childatt;
childrel = heap_open(childrelid, AccessExclusiveLock);
/* check for child relation in use in this session */
if (childrel->rd_refcnt != 1)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_IN_USE),
errmsg("relation \"%s\" is being used by active queries in this session",
RelationGetRelationName(childrel))));
CheckTableNotInUse(childrel, "ALTER TABLE");
tuple = SearchSysCacheCopyAttName(childrelid, colName);
if (!HeapTupleIsValid(tuple)) /* shouldn't happen */

43
src/backend/commands/trigger.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.210.2.4 2007/08/15 19:15:55 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.210.2.5 2008/05/27 21:13:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -3190,28 +3190,29 @@ AfterTriggerSetState(ConstraintsSetStmt *stmt)
}
/* ----------
* AfterTriggerCheckTruncate()
* Test deferred-trigger status to see if a TRUNCATE is OK.
* AfterTriggerPendingOnRel()
* Test to see if there are any pending after-trigger events for rel.
*
* The argument is a list of OIDs of relations due to be truncated.
* We raise error if there are any pending after-trigger events for them.
* This is used by TRUNCATE, CLUSTER, ALTER TABLE, etc to detect whether
* it is unsafe to perform major surgery on a relation. Note that only
* local pending events are examined. We assume that having exclusive lock
* on a rel guarantees there are no unserviced events in other backends ---
* but having a lock does not prevent there being such events in our own.
*
* In some scenarios it'd be reasonable to remove pending events (more
* specifically, mark them DONE by the current subxact) but without a lot
* of knowledge of the trigger semantics we can't do this in general.
* ----------
*/
void
AfterTriggerCheckTruncate(List *relids)
bool
AfterTriggerPendingOnRel(Oid relid)
{
AfterTriggerEvent event;
int depth;
/*
* Ignore call if we aren't in a transaction. (Shouldn't happen?)
*/
/* No-op if we aren't in a transaction. (Shouldn't happen?) */
if (afterTriggers == NULL)
return;
return false;
/* Scan queued events */
for (event = afterTriggers->events.head;
@ -3221,21 +3222,18 @@ AfterTriggerCheckTruncate(List *relids)
/*
* We can ignore completed events. (Even if a DONE flag is rolled
* back by subxact abort, it's OK because the effects of the TRUNCATE
* must get rolled back too.)
* or whatever must get rolled back too.)
*/
if (event->ate_event & AFTER_TRIGGER_DONE)
continue;
if (list_member_oid(relids, event->ate_relid))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot truncate table \"%s\" because it has pending trigger events",
get_rel_name(event->ate_relid))));
if (event->ate_relid == relid)
return true;
}
/*
* Also scan events queued by incomplete queries. This could only matter
* if a TRUNCATE is executed by a function or trigger within an updating
* if TRUNCATE/etc is executed by a function or trigger within an updating
* query on the same relation, which is pretty perverse, but let's check.
*/
for (depth = 0; depth <= afterTriggers->query_depth; depth++)
@ -3247,13 +3245,12 @@ AfterTriggerCheckTruncate(List *relids)
if (event->ate_event & AFTER_TRIGGER_DONE)
continue;
if (list_member_oid(relids, event->ate_relid))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot truncate table \"%s\" because it has pending trigger events",
get_rel_name(event->ate_relid))));
if (event->ate_relid == relid)
return true;
}
}
return false;
}

4
src/include/commands/tablecmds.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/commands/tablecmds.h,v 1.31.2.1 2007/05/11 20:18:17 tgl Exp $
* $PostgreSQL: pgsql/src/include/commands/tablecmds.h,v 1.31.2.2 2008/05/27 21:13:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -34,6 +34,8 @@ extern void AlterRelationNamespaceInternal(Relation classRel, Oid relOid,
Oid oldNspOid, Oid newNspOid,
bool hasDependEntry);
extern void CheckTableNotInUse(Relation rel, const char *stmt);
extern void ExecuteTruncate(TruncateStmt *stmt);
extern void renameatt(Oid myrelid,

4
src/include/commands/trigger.h
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@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/commands/trigger.h,v 1.59 2006/09/04 21:15:56 tgl Exp $
* $PostgreSQL: pgsql/src/include/commands/trigger.h,v 1.59.2.1 2008/05/27 21:13:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -165,7 +165,7 @@ extern void AfterTriggerEndXact(bool isCommit);
extern void AfterTriggerBeginSubXact(void);
extern void AfterTriggerEndSubXact(bool isCommit);
extern void AfterTriggerSetState(ConstraintsSetStmt *stmt);
extern void AfterTriggerCheckTruncate(List *relids);
extern bool AfterTriggerPendingOnRel(Oid relid);
/*

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