Re: WALInsertLock tuning
Simon Riggs <simon@2ndquadrant.com>
From: Simon Riggs <simon@2ndQuadrant.com>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Jeff Janes <jeff.janes@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2011-06-07T07:55:37Z
Lists: pgsql-hackers
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Introduce compact WAL record for the common case of commit (non-DDL).
- 465883b0a2b4 9.2.0 cited
On Tue, Jun 7, 2011 at 8:27 AM, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> wrote: > On 07.06.2011 10:21, Simon Riggs wrote: >> >> On Mon, Jun 6, 2011 at 11:25 PM, Robert Haas<robertmhaas@gmail.com> >> wrote: >>> >>> It strikes me, though, that we >>> could probably get nearly all of the benefit of this patch by being >>> willing to zero the first sizeof(XLogRecord) bytes following a record, >>> but not the rest of the buffer. That would pretty much wipe out any >>> chance of an xl_prev match, I think, and would likely still get nearly >>> all of the performance benefit. >> >> Which adds something onto the path of every XlogInsert(), rather than >> once per page, so I'm a little hesitant to agree. > > You would only need to do it just before you write out the WAL. I guess > you'd need to grab WALInsertLock in XLogWrite() to prevent more WAL records > from being inserted on the page until you're done zeroing it, though. How would that help? -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services