Date: Sat, 2 Sep 2023 08:21:34 -0700
From: Nathan Bossart <nathandbossart@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Andres Freund <andres@anarazel.de>, Jacob Speidel <jacob@extrahop.com>,
	Will Mortensen <will@extrahop.com>, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17973: Reinit of pgstats entry for dropped DB can break
 autovacuum daemon
Message-ID: <20230902152134.GA3320738@nathanxps13>
References: 
 <CAMpnoC5=njD8tLG9q8XQZKi=1SfLehjVPmLJC+pktzGdfZEgoA@mail.gmail.com>
 <CA+pD2MKw6FwU21efw4+kAziFXWB+cnfxiE1824COmp=0x+jwBQ@mail.gmail.com>
 <ZNbRByjoQlUtTkTb@paquier.xyz>
 <20230812004812.4yev47iili57u4hc@awork3.anarazel.de>
 <ZNlxRmI15e1BtCR6@paquier.xyz>
 <ZPE5qXLuMs+/vx9H@paquier.xyz>
 <20230901025613.GB3097511@nathanxps13>
 <ZPFa/bED0YZc0oE3@paquier.xyz>
 <20230901152024.GA3175143@nathanxps13>
 <ZPJ89h7Z7WOiIoIX@paquier.xyz>
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On Sat, Sep 02, 2023 at 09:08:22AM +0900, Michael Paquier wrote:
> On Fri, Sep 01, 2023 at 08:20:24AM -0700, Nathan Bossart wrote:
>> Something along those lines seems fine to me.  FWIW this is what I had in
>> my head:
>> 
>> 	It is important that MyDatabaseId only be set once we are sure that the
>> 	target database can no longer be concurrently dropped or renamed.  Some
>> 	code depends on this.  For example, without this guarantee,
>> 	pgstat_update_dbstats() could create entries for databases that were
>> 	just dropped, which will lead to problems down the road.
> 
> I'm mostly OK with this formulation as well, but without the second
> sentence and adding as extra that pgstat_update_dbstats() could be
> specifically called in the shutdown callback of the shared statistics.

WFM

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com