Subject: Re: pgsql: autovacuum: handle analyze for partitioned tables
To: Justin Pryzby <pryzby@telsasoft.com>,
 Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>,
 Zhihong Yu <zyu@yugabyte.com>, pgsql-hackers@lists.postgresql.org,
 Yuzuko <yuzukohosoya@gmail.com>
References: 
 <CA+TgmoaVOx7K0BE8xpR=_FwLGEP1kJoSx+oskCsVGmuJq5h4vw@mail.gmail.com>
 <20210409213155.GA23912@alvherre.pgsql> <20210409214508.GV6592@telsasoft.com>
From: Tomas Vondra <tomas.vondra@enterprisedb.com>
Message-ID: <ee587b50-757e-a2e4-15a9-5a74f5f92cd1@enterprisedb.com>
Date: Fri, 9 Apr 2021 23:53:08 +0200
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On 4/9/21 11:45 PM, Justin Pryzby wrote:
> On Fri, Apr 09, 2021 at 05:31:55PM -0400, Alvaro Herrera wrote:
>> On 2021-Apr-09, Robert Haas wrote:
>>
>>> Does this need to worry about new partitions getting attached to a
>>> partitioned table, or old ones getting detached? (Maybe it does
>>> already, not sure.)
>>
>> Good question.  It does not.
> 
> I think there's probably cases where this is desirable, and cases where it's
> undesirable, so I don't think it's necessarily a problem.
> 
> One data point: we do DETACH/ATTACH tables during normal operation, before
> type-promoting ALTERs, to avoid worst-case disk use, and to avoid locking the
> table for a long time.  It'd be undesirable (but maybe of no great consequence)
> to trigger an ALTER when we DETACH them, since we'll re-ATTACH it shortly
> afterwards.
> 
> However, I think DROP should be handled ?
> 

IMHO we should prefer the default behavior which favors having updated
statistics, and maybe have a way to override it for individual commands.
So ATTACH would update changes_since_analyze by default, but it would be
possible to disable that.


regards

-- 
Tomas Vondra
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