Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-09-26 Thread Bruce Momjian
This has been saved for the 8.4 release: http://momjian.postgresql.org/cgi-bin/pgpatches_hold --- Simon Riggs wrote: On Thu, 2007-06-28 at 20:23 -0400, Tom Lane wrote: Simon Riggs [EMAIL PROTECTED] writes: On

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-09-26 Thread Simon Riggs
On Wed, 2007-09-26 at 04:33 -0400, Bruce Momjian wrote: This has been saved for the 8.4 release: http://momjian.postgresql.org/cgi-bin/pgpatches_hold Already applied. -- Simon Riggs 2ndQuadrant http://www.2ndQuadrant.com ---(end of

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-07-18 Thread Simon Riggs
On Wed, 2007-07-18 at 01:01 +0100, Gregory Stark wrote: Bruce Momjian [EMAIL PROTECTED] writes: Where are we on this? Well Simon just sent the reworked patch yesterday so the answer is we haven't started tuning this parameter. (Bruce's message is referring to the discussion about what

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-07-17 Thread Bruce Momjian
Where are we on this? --- Gregory Stark wrote: Simon Riggs [EMAIL PROTECTED] writes: I'd guess that storing 8 per page would be optimal, so each stored xid would track 4,000 transactions - probably around 1 sec worth

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-07-17 Thread Gregory Stark
Bruce Momjian [EMAIL PROTECTED] writes: Where are we on this? Well Simon just sent the reworked patch yesterday so the answer is we haven't started tuning this parameter. (Bruce's message is referring to the discussion about what the optimal value of lsns per clog page would be.) I intend to

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-07-05 Thread Simon Riggs
On Thu, 2007-06-28 at 20:23 -0400, Tom Lane wrote: Simon Riggs [EMAIL PROTECTED] writes: On Thu, 2007-06-28 at 15:16 -0400, Tom Lane wrote: A quick grep suggests that VACUUM FULL might be at risk here. No we're clear: I caught that issue specifically for VACUUM FULL fairly early on. VF

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-07-05 Thread Gregory Stark
Simon Riggs [EMAIL PROTECTED] writes: I'd guess that storing 8 per page would be optimal, so each stored xid would track 4,000 transactions - probably around 1 sec worth of transactions when the feature is used. This is something we can experiment with but I suspect that while 8 might be

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-07-02 Thread Simon Riggs
On Fri, 2007-06-29 at 11:13 -0400, Tom Lane wrote: Simon Riggs [EMAIL PROTECTED] writes: On Thu, 2007-06-28 at 20:23 -0400, Tom Lane wrote: The methodology I suggested earlier (involving tracking LSN only at the level of pg_clog pages) isn't going to make that work, unless you somehow

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-06-29 Thread Simon Riggs
On Thu, 2007-06-28 at 20:23 -0400, Tom Lane wrote: Simon Riggs [EMAIL PROTECTED] writes: On Thu, 2007-06-28 at 15:16 -0400, Tom Lane wrote: A quick grep suggests that VACUUM FULL might be at risk here. No we're clear: I caught that issue specifically for VACUUM FULL fairly early on. VF

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-06-29 Thread Tom Lane
Simon Riggs [EMAIL PROTECTED] writes: On Thu, 2007-06-28 at 20:23 -0400, Tom Lane wrote: The methodology I suggested earlier (involving tracking LSN only at the level of pg_clog pages) isn't going to make that work, unless you somehow force the XID counter forward to the next page boundary.

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-06-28 Thread Tom Lane
Pavan Deolasee [EMAIL PROTECTED] writes: So we suspected an interaction between multiple processes each holding a SHARE lock and setting/checking different bits in the infomask and we could theoritically say that such interaction can potentially lead to missing hint bit updates. Yeah. This

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-06-28 Thread Heikki Linnakangas
Pavan Deolasee wrote: During one of HOT stress tests, an asserition failed at tqual.c:1178 in HeapTupleSatisfiesVacuum(). The assertion failure looked really strange because the assertion checks for HEAP_XMAX_COMMITTED which we set just couple of lines above. I inspected the core dump and found

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-06-28 Thread Tom Lane
Heikki Linnakangas [EMAIL PROTECTED] writes: AFAICS, we can just simply remove the assertion. But is there any codepaths that assume that after calling HeapTupleSatisfiesSnapshot, all appropriate hint bits are set? There had better not be, since we are going to postpone setting hint bits for

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-06-28 Thread Alvaro Herrera
Tom Lane escribió: Heikki Linnakangas [EMAIL PROTECTED] writes: AFAICS, we can just simply remove the assertion. But is there any codepaths that assume that after calling HeapTupleSatisfiesSnapshot, all appropriate hint bits are set? There had better not be, since we are going to

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-06-28 Thread Tom Lane
Alvaro Herrera [EMAIL PROTECTED] writes: Tom Lane escribió: A quick grep suggests that VACUUM FULL might be at risk here. That particular case seems easily fixed since VACUUM FULL must hold an exclusive lock; and we can forcibly set sync commit for VACUUM FULL. Uh, that wouldn't help. The

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-06-28 Thread Simon Riggs
On Thu, 2007-06-28 at 15:16 -0400, Tom Lane wrote: Heikki Linnakangas [EMAIL PROTECTED] writes: AFAICS, we can just simply remove the assertion. But is there any codepaths that assume that after calling HeapTupleSatisfiesSnapshot, all appropriate hint bits are set? There had better not

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-06-28 Thread Simon Riggs
On Thu, 2007-06-28 at 15:29 -0400, Alvaro Herrera wrote: Tom Lane escribió: Heikki Linnakangas [EMAIL PROTECTED] writes: AFAICS, we can just simply remove the assertion. But is there any codepaths that assume that after calling HeapTupleSatisfiesSnapshot, all appropriate hint bits

Re: [HACKERS] SetBufferCommitInfoNeedsSave and race conditions

2007-06-28 Thread Tom Lane
Simon Riggs [EMAIL PROTECTED] writes: On Thu, 2007-06-28 at 15:16 -0400, Tom Lane wrote: A quick grep suggests that VACUUM FULL might be at risk here. No we're clear: I caught that issue specifically for VACUUM FULL fairly early on. VF assumes all hint bits are set after the first scan, so we