From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | "Simon Riggs" <simon(at)2ndquadrant(dot)com> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: COMMIT NOWAIT Performance Option |
Date: | 2007-02-27 04:04:07 |
Message-ID: | 10498.1172549047@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
"Simon Riggs" <simon(at)2ndquadrant(dot)com> writes:
> COMMIT NOWAIT can co-exist with the normal form of COMMIT and does not
> threaten the consistency or robustness of other COMMIT modes. Read that
> again and think about it, before we go further, please.
I read that, and thought about it, and don't think I believe it. The
problem is that there are more interconnections between different
transactions than you're allowing for. In particular you need to
justify that the behavior is safe for non-transactional operations like
btree page splits and pg_clog buffer page writes. The idea that's
particularly bothering me at the moment is that after a system crash,
we might come back up in a state where a NOWAIT transaction appears
committed when its updates didn't all get to disk. "Database corrupt"
is a situation that threatens all your transactions...
> New commit mode is available by explicit command, or as a default
> setting that will be applied to all COMMITs, or both.
I dislike introducing new nonstandard syntax ("Oracle compatible" is not
standard). If we did this I'd vote for control via a GUC setting only;
I think that is more useful anyway, as an application can be made to run
with such a setting without invasive source code changes.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Jeroen T. Vermeulen | 2007-02-27 04:05:45 | Re: COMMIT NOWAIT Performance Option |
Previous Message | Matthew T. O'Connor | 2007-02-27 03:53:34 | Re: autovacuum next steps, take 2 |