From: Justin Pryzby <pryzby@telsasoft.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Andrey Borodin <x4mmm@yandex-team.ru>
Cc: pgsql-hackers@postgresql.org, Thomas Munro <thomas.munro@gmail.com>
Subject: Re: Different compression methods for FPI
Date: Sat, 26 Jun 2021 18:11:26 -0500
Message-ID: <20210626231126.GR29179@telsasoft.com> (raw)
In-Reply-To: <YNFeyiPYA9jRzcKY@paquier.xyz>
References: <20210315003135.GL29463@telsasoft.com>
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<20210321193004.GA4203@telsasoft.com>
<YKIelANwse+k2JxT@paquier.xyz>
<20210519030618.GS373@telsasoft.com>
<YKTa4+kTFkb3EIBs@paquier.xyz>
<20210525044444.GV3676@telsasoft.com>
<CAFiTN-thohtHGzp4dJ1QWc359qb43mVfrELeVcS5BwFuquRLtg@mail.gmail.com>
<20210622031358.GF29179@telsasoft.com>
<YNFeyiPYA9jRzcKY@paquier.xyz>
On Tue, Jun 22, 2021 at 12:53:46PM +0900, Michael Paquier wrote:
> > So the patches that you say are unrelated still seem to me to be a
> > prerequisite .
>
> I may be missing something, of course, but I still don't see why
> that's necessary? We don't get any test failures on HEAD by switching
> wal_compression to on, no? That's easy enough to test with a two-line
> change that changes the default.
Curious. I found that before a4d75c86bf, there was an issue without the
"extra" patches.
|commit a4d75c86bf15220df22de0a92c819ecef9db3849
|Author: Tomas Vondra <tomas.vondra@postgresql.org>
|Date: Fri Mar 26 23:22:01 2021 +0100
|
| Extended statistics on expressions
I have no idea why that patch changes the behavior, but before a4d7, this patch
series failed like:
|$ time time make -C src/test/recovery check
...
|# Failed test 'new xid after restart is greater'
|# at t/011_crash_recovery.pl line 53.
|# '539'
|# >
|# '539'
|
|# Failed test 'xid is aborted after crash'
|# at t/011_crash_recovery.pl line 57.
|# got: 'committed'
|# expected: 'aborted'
|# Looks like you failed 2 tests of 3.
|t/011_crash_recovery.pl .............. Dubious, test returned 2 (wstat 512, 0x200)
|Failed 2/3 subtests
I checked that my most recent WAL compression patch applied on top of
a4d75c86bf works ok without the "extra" patches but fails when applied to
a4d75c86bf~1.
I think Andrey has been saying that since this already fails with PGLZ wal
compression, we could consider this to be a pre-existing problem. I'm not
thrilled with that interpretation, but it's not wrong.
--
Justin
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To: pgsql-hackers@postgresql.org
Cc: pryzby@telsasoft.com, michael@paquier.xyz, dilipbalaut@gmail.com, x4mmm@yandex-team.ru, thomas.munro@gmail.com
Subject: Re: Different compression methods for FPI
In-Reply-To: <20210626231126.GR29179@telsasoft.com>
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