pg.ddx.io  pgsql-hackers@postgresql.org mailing list archive  

help / color / mirror / Atom feed
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
Cc: Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
Cc: Rushabh Lathia <rushabh.lathia@gmail.com>
Cc: Michael Paquier <michael.paquier@gmail.com>
Subject: Re: postgres_fdw: perform UPDATE/DELETE .. RETURNING on a join directly
Date: Mon, 05 Mar 2018 00:51:52 -0500
Message-ID: <21358.1520229112@sss.pgh.pa.us> (raw)
In-Reply-To: <CAFjFpRdQVqCrYXN3F=jj_wftSp2gD-rPXKS-ogoQLAmrmKxwuQ@mail.gmail.com>
References: <5A438A45.2000909@lab.ntt.co.jp>
	<5A57193A.2080003@lab.ntt.co.jp>
	<CA+TgmoYef9czAA1gJeqh4v47Tv=dqOp4EfdU6bV8EYkOdCwvUw@mail.gmail.com>
	<6166.1518044513@sss.pgh.pa.us>
	<CA+TgmoaxGGZyUAWQMz7c-3V85TV5-w2wmvpOYrLnALi2d9Z-dQ@mail.gmail.com>
	<5A7BE8E6.200@lab.ntt.co.jp>
	<28606.1518105934@sss.pgh.pa.us>
	<CA+Tgmobf+AXEwO4r0oCkvNhkaVnxPgoJaApoX+rAi0G7-N-Dyg@mail.gmail.com>
	<5A7CFDDA.8050906@lab.ntt.co.jp>
	<5A7D76CF.8080601@lab.ntt.co.jp>
	<CA+TgmoaAQCn0+xh3JG2avn35Lukj2NVmhxVi7hE2CwzSUQ-5ag@mail.gmail.com>
	<20134.1518201188@sss.pgh.pa.us>
	<CA+TgmoY5KNf-Y=zOdHVfa8Lmo=OMJe=dBpP-noT_1fdVK6EYPA@mail.gmail.com>
	<18653.1518297871@sss.pgh.pa.us>
	<5A82DCCE.3060107@lab.ntt.co.jp>
	<29147.1519769644@sss.pgh.pa.us>
	<CA+Tgmob_WGK+vKzE6FmrMmuwuv4myntfRAkEbo+tsDt9xUwCLQ@mail.gmail.com>
	<23783.1519929258@sss.pgh.pa.us>
	<5A9928F1.2010206@lab.ntt.co.jp>
	<CA+TgmoaNWpQ+F7_DtiJpc62PUJ6JQBAQpT1H7CBrjKmryGGgkw@mail.gmail.com>
	<CA+TgmoZOpGnmss2dpOAktHc30NS=StmLw-ChkJkd74DLo_nyEA@mail.gmail.com>
	<! 5A9CB7B9.2040008@lab.ntt.co.jp>
	<CAFjFpRdQVqCrYXN3F=jj_wftSp2gD-rPXKS-ogoQLAmrmKxwuQ@mail.gmail.com>

Ashutosh Bapat <ashutosh.bapat@enterprisedb.com> writes:
> On Mon, Mar 5, 2018 at 8:51 AM, Etsuro Fujita
> <fujita.etsuro@lab.ntt.co.jp> wrote:
>> Totally outdated stats used in query planning causes the failures? ANALYZE
>> right before the plan-changing queries would fix the failures?

> I think the testcase file for postgres_fdw has grown really large over
> the time, as we have added more pushdown. Since most of the queries in
> that file use the same tables created at the beginning of the file,
> changes somewhere in-between (esp. DMLs) affect the following queries.
> It's getting hard to add a test query in that file and expect stable
> results.

The thing that I find curious, now that we've shut off autovacuum
altogether on those tables, is that we *still* aren't getting stable
results.  How can that be?  Yeah, if you add another query in the middle
you might find that changing later results, but for any fixed contents of
the test script, why isn't the buildfarm getting the same answers that the
patch author and committer got?  I could believe different results on
32-bit and 64-bit hardware, but that does not seem to be quite the pattern
we're seeing.

> I think, it's time to split the file into at least two one
> for queries and one for DMLs.

That seems largely irrelevant right at this point.  First we have to
explain the instability.

			regards, tom lane




view thread (33+ messages)  latest in thread

Message-ID: <21358.1520229112@sss.pgh.pa.us>
Permalink:  ../21358.1520229112@sss.pgh.pa.us/
Also on:    postgresql.org/message-id/21358.1520229112@sss.pgh.pa.us

 · 

reply
Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: pgsql-hackers@postgresql.org
  Cc: tgl@sss.pgh.pa.us, ashutosh.bapat@enterprisedb.com, fujita.etsuro@lab.ntt.co.jp, robertmhaas@gmail.com, rushabh.lathia@gmail.com, michael.paquier@gmail.com
  Subject: Re: postgres_fdw: perform UPDATE/DELETE .. RETURNING on a join directly
  In-Reply-To: <21358.1520229112@sss.pgh.pa.us>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox