Re: [GENERAL] ANALYZE getting dead tuple count hopelessly wrong - Mailing list pgsql-hackers

From Simon Riggs
Subject Re: [GENERAL] ANALYZE getting dead tuple count hopelessly wrong
Date
Msg-id 1207037061.4238.8.camel@ebony.site
Whole thread Raw
In response to Re: [GENERAL] ANALYZE getting dead tuple count hopelessly wrong  ("Pavan Deolasee" <pavan.deolasee@gmail.com>)
Responses Re: [GENERAL] ANALYZE getting dead tuple count hopelessly wrong  (Tom Lane <tgl@sss.pgh.pa.us>)
List 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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