| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
| Cc: | Simon Riggs <simon(at)2ndQuadrant(dot)com>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, pgsql-bugs(at)postgresql(dot)org |
| Subject: | Re: BUG #4879: bgwriter fails to fsync the file in recovery mode |
| Date: | 2009-06-25 22:31:53 |
| Message-ID: | 7671.1245969113@sss.pgh.pa.us |
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| Lists: | pgsql-bugs |
Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> Tom Lane wrote:
>> The behavior you seem to have in mind would be completely disastrous
>> from a performance standpoint, as we'd be writing and fsyncing
>> pg_control constantly during a recovery.
> Please define "constantly". We discussed that part of the patch here:
> http://archives.postgresql.org/message-id/498AB55D.50408@enterprisedb.com
Okay, after reading the code a bit more I found this:
/*
* To avoid having to update the control file too often, we update it
* all the way to the last record being replayed, even though 'lsn'
* would suffice for correctness.
*/
which should alleviate the too-many-writes syndrome. Never mind that
complaint then. (But shouldn't there be an Assert that this is >= lsn?)
regards, tom lane
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