Re: Resumable vacuum proposal and design overview

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: tomas(at)tuxteam(dot)de
Cc: Galy Lee <lee(dot)galy(at)oss(dot)ntt(dot)co(dot)jp>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Resumable vacuum proposal and design overview
Date: 2007-02-26 18:39:40
Message-ID: 4403.1172515180@sss.pgh.pa.us
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tomas(at)tuxteam(dot)de writes:
> WARNING: I don't really know what I'm talking about -- but considering
> that vaccuming a large table across several "maintainance windows" is
> one of the envisioned scenarios, it might make sense to try to update
> the statistics (i.e. to do partially step 7) on each partial run.
> Otherwise the table's stats might wander off for quite long times?

You can handle that by issuing ANALYZE as a separate operation; I see no
need to complicate this proposal even further by having it make magic
changes to the behavior of VACUUM ANALYZE.

Or were you speaking of the pg_class.reltuples count? Keeping that
from diverging indefinitely far from reality will indeed be a problem
with this sort of thing. We've already seen some issues related to the
stats collector's similar count.

regards, tom lane

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