Re: WAL copying includes vacuum, reindex, etc?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: d(dot)wall(at)computer(dot)org, pgsql-admin(at)postgresql(dot)org
Subject: Re: WAL copying includes vacuum, reindex, etc?
Date: 2008-01-15 18:07:32
Message-ID: 26472.1200420452@sss.pgh.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-admin

Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> All of those commands produce WAL for critical changes to data blocks,
> so those are passed through correctly.

> Hint bits are not set following recovery, so a full database VACUUM may
> help later performance, depends upon your access patterns.

That's only partially true. Full-page images in WAL will propagate hint
bits, so in practice you could expect that only about one checkpoint
cycle's worth of hint information is missing. If you'd been running
with full_page_writes = off then this doesn't hold, and in that case
I'd agree that a forced vacuum might be worth the trouble.

regards, tom lane

In response to

Browse pgsql-admin by date

  From Date Subject
Next Message Bhella Paramjeet-PFCW67 2008-01-15 18:12:31 Re: Pg_statio_user_tables view does not get populated
Previous Message Tom Lane 2008-01-15 18:04:06 Re: Pg_statio_user_tables view does not get populated