Re: document the need to analyze partitioned tables

From: Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>
To: Justin Pryzby <pryzby(at)telsasoft(dot)com>
Cc: Bruce Momjian <bruce(at)momjian(dot)us>, Nathan Bossart <nathandbossart(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Álvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, yuzuko <yuzukohosoya(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: document the need to analyze partitioned tables
Date: 2023-01-18 19:26:10
Message-ID: a36b9ef49c02bb0980b1d100222f1f6690cd39c6.camel@cybertec.at
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On Wed, 2023-01-18 at 11:49 -0600, Justin Pryzby wrote:
> I tweaked this a bit to end up with:
>
> > -    Partitioned tables are not processed by autovacuum.  Statistics
> > -    should be collected by running a manual <command>ANALYZE</command> when it is
> > +    The leaf partitions of a partitioned table are normal tables and are processed
> > +    by autovacuum; however, autovacuum does not process the partitioned table itself.
> > +    This is no problem as far as <command>VACUUM</command> is concerned, since
> > +    there's no need to vacuum the empty, partitioned table.  But, as mentioned in
> > +    <xref linkend="vacuum-for-statistics"/>, it also means that autovacuum won't
> > +    run <command>ANALYZE</command> on the partitioned table.
> > +    Although statistics are automatically gathered on its leaf partitions, some queries also need
> > +    statistics on the partitioned table to run optimally.  You should collect statistics by
> > +    running a manual <command>ANALYZE</command> when the partitioned table is
> >      first populated, and again whenever the distribution of data in its
> >      partitions changes significantly.
> >     </para>
>
> "partitions are normal tables" was techically wrong, as partitions can
> also be partitioned.

I am fine with your tweaks. I think this is good to go.

Yours,
Laurenz Albe

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