| From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Stuart Brooks <stuartb(at)cat(dot)co(dot)za>, pgsql-general(at)postgresql(dot)org, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] ANALYZE getting dead tuple count hopelessly wrong |
| Date: | 2008-04-01 08:04:21 |
| Message-ID: | 1207037061.4238.8.camel@ebony.site |
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| Thread: | |
| Lists: | pgsql-general pgsql-hackers |
On Tue, 2008-04-01 at 13:07 +0530, Pavan Deolasee wrote:
> Please see the attached patch. One change I made is to hold the SHARE lock
> on the page while ANALYZE is reading tuples from it. I thought it would
> be a right thing to do instead of repeatedly acquiring/releasing the lock.
ANALYZE is a secondary task and so we shouldn't be speeding it up at the
possible expense of other primary tasks. So I think holding locks for
longer than minimum is not good in this case and I see no reason to make
the change described.
We can speed up ANALYZE by using the background reader to preread the
blocks, assuming bgreader will happen one day.
--
Simon Riggs
2ndQuadrant http://www.2ndQuadrant.com
PostgreSQL UK 2008 Conference: http://www.postgresql.org.uk
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