Date: Wed, 28 Oct 2020 20:13:48 +0100
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: "David G. Johnston" <david.g.johnston@gmail.com>,
	=?utf-8?B?RmFicsOtemlv?= Mello <fabriziomello@gmail.com>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Add important info about ANALYZE after create Functional Index
Message-ID: <20201028191348.u4jwtawz4c533xge@development>
References: 
 <CAFcNs+qpFPmiHd1oTXvcPdvAHicJDA9qBUSujgAhUMJyUMb+SA@mail.gmail.com>
 <CAKFQuwb9GFe4oM3k9bsn7GOk5_jfow-9SpWocAG4xAYVp9nLjg@mail.gmail.com>
 <20201028185538.fzux2lhim472h46o@development>
 <1442677.1603911939@sss.pgh.pa.us>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Disposition: inline
In-Reply-To: <1442677.1603911939@sss.pgh.pa.us>
Precedence: bulk

On Wed, Oct 28, 2020 at 03:05:39PM -0400, Tom Lane wrote:
>Tomas Vondra <tomas.vondra@2ndquadrant.com> writes:
>> On Mon, Oct 26, 2020 at 03:46:10PM -0700, David G. Johnston wrote:
>>> It would seem preferable to call the lack of auto-analyzing after these
>>> operations a bug and back-patch a fix that injects an analyze side-effect
>>> just before their completion.  It doesn't have to be smart either,
>>> analyzing things even if the created (or newly validated) index doesn't
>>> have statistics of its own isn't a problem in my book.
>
>> I agree the lack of stats may be quite annoying and cause issues, but my
>> guess is the chances of backpatching such change are about 0.000001%. We
>> have a usable 'workaround' for this - manual analyze.
>
>This doesn't seem clearly different from any other situation where
>auto-analyze doesn't react fast enough to suit you.  I would not
>call it a bug, at least not without a wholesale redefinition of
>how auto-analyze is supposed to work.  As a close analogy, we
>don't make any effort to force an immediate auto-analyze after
>CREATE STATISTICS.
>

True.

>I don't see anything in the CREATE STATISTICS man page pointing
>that out, either.  But there's probably room for "Notes" entries
>about it in both places.
>

I agree. I'll add it to my TODO list for the next CF.


regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services