Re: New vacuum option to do only freezing

From: Michael Paquier <michael(at)paquier(dot)xyz>
To: Peter Geoghegan <pg(at)bowt(dot)ie>
Cc: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Robert Haas <robertmhaas(at)gmail(dot)com>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, "Bossart, Nathan" <bossartn(at)amazon(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: New vacuum option to do only freezing
Date: 2019-06-20 06:50:32
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On Wed, Jun 19, 2019 at 12:51:41PM -0700, Peter Geoghegan wrote:
> On Tue, Jun 18, 2019 at 10:39 PM Michael Paquier <michael(at)paquier(dot)xyz> wrote:
>> +INSERT INTO no_index_cleanup(i, t) VALUES(1, repeat('1234567890',30000));
>> Do we really need a string as long as that?
> Specifying EXTERNAL storage might make things easier. I have used
> PLAIN storage to test the 1/3 of a page restriction within nbtree, and
> to test a bug in amcheck that was related to TOAST compression.

Ah, good point here. That makes sense.

>> It seems to me that we'd want tests to make sure that indexes are
>> actually cleaned up, where pageinspect could prove to be useful.
> That definitely seems preferable, but it'll be a bit tricky to do it
> in a way that doesn't run into buildfarm issues due to alignment. I
> suggest an index on a text column to avoid problems.

I am not completely sure how tricky that may be, so I'll believe you
on this one :)

So, to keep things simple and if we want to get something into v12, I
would suggest to just stress more combinations even if the changes are
not entirely visible yet. If we get a couple of queries to run with
the option disabled on the table, its toast or both by truncating and
filling in the table in-between, we may be able to catch some issues
by stressing those code paths.

And I finish with the attached. Thoughts?

Attachment Content-Type Size
toast_vacuum_index_cleanup_v4.patch text/x-diff 6.1 KB

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