Re: WIP: Collecting statistics on CSV file data

From: David Fetter <david(at)fetter(dot)org>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Marti Raudsepp <marti(at)juffo(dot)org>, Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: WIP: Collecting statistics on CSV file data
Date: 2011-09-21 00:22:32
Message-ID: 20110921002232.GA18333@fetter.org
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On Tue, Sep 20, 2011 at 11:13:05AM -0400, Tom Lane wrote:
> Marti Raudsepp <marti(at)juffo(dot)org> writes:
> > 2011/9/12 Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp>:
> >> This is called when ANALYZE command is executed. (ANALYZE
> >> command should be executed because autovacuum does not analyze foreign
> >> tables.)
>
> > This is a good idea.
>
> > However, if adding these statistics requires an explicit ANALYZE
> > command, then we should also have a command for resetting the
> > collected statistics -- to get it back into the un-analyzed state.
>
> Uh, why? There is no UNANALYZE operation for ordinary tables, and
> I've never heard anyone ask for one.
>
> If you're desperate you could manually delete the relevant rows in
> pg_statistic, a solution that would presumably work for foreign tables
> too.
>
> Probably a more interesting question is why we wouldn't change
> autovacuum so that it calls this automatically for foreign tables.

How about a per-table setting that tells autovacuum whether to do
this? Come to think of it, all of per-FDW, per-remote and per-table
settings would be handy, so people could express things like, "all CSV
files except these three, all PostgreSQL connections on the
10.1.0.0/16 network, and these two tables in Oracle."

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
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