Message-ID: <fdc0cd8f903066d42132faca60cd8dbf3f8fa09e.camel@cybertec.at>
Subject: Re: Autovacuum on partitioned table
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: yuzuko <yuzukohosoya@gmail.com>, PostgreSQL Hackers
	 <pgsql-hackers@lists.postgresql.org>
Cc: Greg Stark <stark@mit.edu>
Date: Mon, 02 Dec 2019 10:19:01 +0100
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On Mon, 2019-12-02 at 18:02 +0900, yuzuko wrote:
> Greg reported in [1] before, autovacuum ignores partitioned tables.
> That is, even if individual partitions’ statistics are updated, its parent's
> statistics are not updated.  This is TODO for declarative partitioning.
> As Amit mentioned in [2], a way to make parent's statistics from
> partitions' statistics without scanning the partitions would be nice,
> but it will need a lot of modifications.  So I tried to fix that using the
> current analyze method.
> 
> The summary of the attached patch is as follows:
> * If the relation is a partitioned table, check its children if they need
>   vacuum or analyze.  Children need to do that are added to
>   a table list for autovacuuum.  At least one child is added to the list,
>   the partitioned table is also added to the list.  Then, autovacuum
>   runs on all the tables in the list.

That means that all partitions are vacuumed if only one of them needs it,
right?  This will result in way more vacuuming than necessary.

Wouldn't it be an option to update the partitioned table's statistics
whenever one of the partitions is vacuumed?

Yours,
Laurenz Albe