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Fix interaction between materializing holdable cursors and firing

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deferred triggers: either one can create more work for the other,
so we have to loop till it's all gone.  Per example from andrew@supernews.
Add a regression test to help spot trouble in this area in future.
REL8_1_STABLE
Tom Lane 21 years ago
parent 0c400f1bbc
commit c3294f1cbf
7 changed files with 187 additions and 70 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. 34
      src/backend/access/transam/xact.c
  2. 44
      src/backend/commands/trigger.c
  3. 92
      src/backend/utils/mmgr/portalmem.c
  4. 6
      src/include/commands/trigger.h
  5. 3
      src/include/utils/portal.h
  6. 35
      src/test/regress/expected/portals.out
  7. 43
      src/test/regress/sql/portals.sql

34
src/backend/access/transam/xact.c
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@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.198 2005/03/28 01:50:33 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.199 2005/04/11 19:51:14 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1439,16 +1439,32 @@ CommitTransaction(void)
/*
* Do pre-commit processing (most of this stuff requires database
* access, and in fact could still cause an error...)
*
* It is possible for CommitHoldablePortals to invoke functions that
* queue deferred triggers, and it's also possible that triggers create
* holdable cursors. So we have to loop until there's nothing left to
* do.
*/
for (;;)
{
/*
* Fire all currently pending deferred triggers.
*/
AfterTriggerFireDeferred();
/*
* Tell the trigger manager that this transaction is about to be
* committed. He'll invoke all trigger deferred until XACT before we
* really start on committing the transaction.
*/
AfterTriggerEndXact();
/*
* Convert any open holdable cursors into static portals. If there
* weren't any, we are done ... otherwise loop back to check if they
* queued deferred triggers. Lather, rinse, repeat.
*/
if (!CommitHoldablePortals())
break;
}
/* Now we can shut down the deferred-trigger manager */
AfterTriggerEndXact(true);
/* Close open cursors */
/* Close any open regular cursors */
AtCommit_Portals();
/*
@ -1649,7 +1665,7 @@ AbortTransaction(void)
/*
* do abort processing
*/
AfterTriggerAbortXact();
AfterTriggerEndXact(false);
AtAbort_Portals();
AtEOXact_LargeObject(false); /* 'false' means it's abort */
AtAbort_Notify();

44
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 1.183 2005/03/29 03:01:30 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.184 2005/04/11 19:51:15 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -2441,14 +2441,18 @@ AfterTriggerEndQuery(EState *estate)
/* ----------
* AfterTriggerEndXact()
* AfterTriggerFireDeferred()
*
* Called just before the current transaction is committed. At this
* time we invoke all DEFERRED triggers and tidy up.
* time we invoke all pending DEFERRED triggers.
*
* It is possible for other modules to queue additional deferred triggers
* during pre-commit processing; therefore xact.c may have to call this
* multiple times.
* ----------
*/
void
AfterTriggerEndXact(void)
AfterTriggerFireDeferred(void)
{
AfterTriggerEventList *events;
@ -2463,14 +2467,14 @@ AfterTriggerEndXact(void)
* for them to use. (Since PortalRunUtility doesn't set a snap for
* COMMIT, we can't assume ActiveSnapshot is valid on entry.)
*/
if (afterTriggers->events.head != NULL)
events = &afterTriggers->events;
if (events->head != NULL)
ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
/*
* Run all the remaining triggers. Loop until they are all gone,
* just in case some trigger queues more for us to do.
*/
events = &afterTriggers->events;
while (afterTriggerMarkEvents(events, NULL, false))
{
CommandId firing_id = afterTriggers->firing_counter++;
@ -2478,34 +2482,26 @@ AfterTriggerEndXact(void)
afterTriggerInvokeEvents(events, firing_id, NULL, true);
}
/*
* Forget everything we know about AFTER triggers.
*
* Since all the info is in TopTransactionContext or children thereof, we
* need do nothing special to reclaim memory.
*/
afterTriggers = NULL;
Assert(events->head == NULL);
}
/* ----------
* AfterTriggerAbortXact()
* AfterTriggerEndXact()
*
* The current transaction is finishing.
*
* The current transaction has entered the abort state.
* All outstanding triggers are canceled so we simply throw
* Any unfired triggers are canceled so we simply throw
* away anything we know.
*
* Note: it is possible for this to be called repeatedly in case of
* error during transaction abort; therefore, do not complain if
* already closed down.
* ----------
*/
void
AfterTriggerAbortXact(void)
AfterTriggerEndXact(bool isCommit)
{
/*
* Ignore call if we aren't in a transaction. (Need this to survive
* repeat call in case of error during transaction abort.)
*/
if (afterTriggers == NULL)
return;
/*
* Forget everything we know about AFTER triggers.
*

92
src/backend/utils/mmgr/portalmem.c
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@ -12,7 +12,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/mmgr/portalmem.c,v 1.77 2005/01/26 23:20:21 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/mmgr/portalmem.c,v 1.78 2005/04/11 19:51:15 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -416,18 +416,14 @@ DropDependentPortals(MemoryContext queryContext)
*
* Any holdable cursors created in this transaction need to be converted to
* materialized form, since we are going to close down the executor and
* release locks. Remove all other portals created in this transaction.
* Portals remaining from prior transactions should be left untouched.
* release locks. Other portals are not touched yet.
*
* XXX This assumes that portals can be deleted in a random order, ie,
* no portal has a reference to any other (at least not one that will be
* exercised during deletion). I think this is okay at the moment, but
* we've had bugs of that ilk in the past. Keep a close eye on cursor
* references...
* Returns TRUE if any holdable cursors were processed, FALSE if not.
*/
void
AtCommit_Portals(void)
bool
CommitHoldablePortals(void)
{
bool result = false;
HASH_SEQ_STATUS status;
PortalHashEnt *hentry;
@ -437,27 +433,9 @@ AtCommit_Portals(void)
{
Portal portal = hentry->portal;
/*
* Do not touch active portals --- this can only happen in the
* case of a multi-transaction utility command, such as VACUUM.
*
* Note however that any resource owner attached to such a portal is
* still going to go away, so don't leave a dangling pointer.
*/
if (portal->status == PORTAL_ACTIVE)
{
portal->resowner = NULL;
continue;
}
/*
* Do nothing else to cursors held over from a previous
* transaction.
*/
if (portal->createSubid == InvalidSubTransactionId)
continue;
/* Is it a holdable portal created in the current xact? */
if ((portal->cursorOptions & CURSOR_OPT_HOLD) &&
portal->createSubid != InvalidSubTransactionId &&
portal->status == PORTAL_READY)
{
/*
@ -484,12 +462,60 @@ AtCommit_Portals(void)
* as not belonging to this transaction.
*/
portal->createSubid = InvalidSubTransactionId;
result = true;
}
else
}
return result;
}
/*
* Pre-commit processing for portals.
*
* Remove all non-holdable portals created in this transaction.
* Portals remaining from prior transactions should be left untouched.
*
* XXX This assumes that portals can be deleted in a random order, ie,
* no portal has a reference to any other (at least not one that will be
* exercised during deletion). I think this is okay at the moment, but
* we've had bugs of that ilk in the past. Keep a close eye on cursor
* references...
*/
void
AtCommit_Portals(void)
{
HASH_SEQ_STATUS status;
PortalHashEnt *hentry;
hash_seq_init(&status, PortalHashTable);
while ((hentry = (PortalHashEnt *) hash_seq_search(&status)) != NULL)
{
Portal portal = hentry->portal;
/*
* Do not touch active portals --- this can only happen in the
* case of a multi-transaction utility command, such as VACUUM.
*
* Note however that any resource owner attached to such a portal is
* still going to go away, so don't leave a dangling pointer.
*/
if (portal->status == PORTAL_ACTIVE)
{
/* Zap all non-holdable portals */
PortalDrop(portal, true);
portal->resowner = NULL;
continue;
}
/*
* Do nothing to cursors held over from a previous transaction
* (including holdable ones just frozen by CommitHoldablePortals).
*/
if (portal->createSubid == InvalidSubTransactionId)
continue;
/* Zap all non-holdable portals */
PortalDrop(portal, true);
}
}

6
src/include/commands/trigger.h
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@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/commands/trigger.h,v 1.52 2005/03/25 21:57:59 tgl Exp $
* $PostgreSQL: pgsql/src/include/commands/trigger.h,v 1.53 2005/04/11 19:51:15 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -157,8 +157,8 @@ extern void ExecARUpdateTriggers(EState *estate,
extern void AfterTriggerBeginXact(void);
extern void AfterTriggerBeginQuery(void);
extern void AfterTriggerEndQuery(EState *estate);
extern void AfterTriggerEndXact(void);
extern void AfterTriggerAbortXact(void);
extern void AfterTriggerFireDeferred(void);
extern void AfterTriggerEndXact(bool isCommit);
extern void AfterTriggerBeginSubXact(void);
extern void AfterTriggerEndSubXact(bool isCommit);

3
src/include/utils/portal.h
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@ -39,7 +39,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/utils/portal.h,v 1.54 2004/12/31 22:03:46 pgsql Exp $
* $PostgreSQL: pgsql/src/include/utils/portal.h,v 1.55 2005/04/11 19:51:16 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -182,6 +182,7 @@ typedef struct PortalData
/* Prototypes for functions in utils/mmgr/portalmem.c */
extern void EnablePortalManager(void);
extern bool CommitHoldablePortals(void);
extern void AtCommit_Portals(void);
extern void AtAbort_Portals(void);
extern void AtCleanup_Portals(void);

35
src/test/regress/expected/portals.out
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@ -773,3 +773,38 @@ FETCH ALL FROM c;
(15 rows)
ROLLBACK;
--
-- Test behavior of both volatile and stable functions inside a cursor;
-- in particular we want to see what happens during commit of a holdable
-- cursor
--
create temp table tt1(f1 int);
create function count_tt1_v() returns int8 as
'select count(*) from tt1' language sql volatile;
create function count_tt1_s() returns int8 as
'select count(*) from tt1' language sql stable;
begin;
insert into tt1 values(1);
declare c1 cursor for select count_tt1_v(), count_tt1_s();
insert into tt1 values(2);
fetch all from c1;
count_tt1_v | count_tt1_s
-------------+-------------
2 | 1
(1 row)
rollback;
begin;
insert into tt1 values(1);
declare c2 cursor with hold for select count_tt1_v(), count_tt1_s();
insert into tt1 values(2);
commit;
delete from tt1;
fetch all from c2;
count_tt1_v | count_tt1_s
-------------+-------------
2 | 1
(1 row)
drop function count_tt1_v();
drop function count_tt1_s();

43
src/test/regress/sql/portals.sql
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@ -235,3 +235,46 @@ SELECT declares_cursor('AB%');
FETCH ALL FROM c;
ROLLBACK;
--
-- Test behavior of both volatile and stable functions inside a cursor;
-- in particular we want to see what happens during commit of a holdable
-- cursor
--
create temp table tt1(f1 int);
create function count_tt1_v() returns int8 as
'select count(*) from tt1' language sql volatile;
create function count_tt1_s() returns int8 as
'select count(*) from tt1' language sql stable;
begin;
insert into tt1 values(1);
declare c1 cursor for select count_tt1_v(), count_tt1_s();
insert into tt1 values(2);
fetch all from c1;
rollback;
begin;
insert into tt1 values(1);
declare c2 cursor with hold for select count_tt1_v(), count_tt1_s();
insert into tt1 values(2);
commit;
delete from tt1;
fetch all from c2;
drop function count_tt1_v();
drop function count_tt1_s();

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