From: Tom Lane <tgl@sss.pgh.pa.us>
To: Julien Rouhaud <rjuju123@gmail.com>
cc: Michael Paquier <michael@paquier.xyz>,
        pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Add an optional timeout clause to isolationtester step.
In-reply-to: <20200307211709.6kfpiddif4uxafg5@nol>
References: <20200303092551.GB1890@paquier.xyz>
 <20200304051510.GE2593@paquier.xyz>
 <CAOBaU_Z=qkE42VQ25mps+zyAz+WUn3wZoev4uhGW+gAXBBS2YA@mail.gmail.com>
 <20200305035354.GQ2593@paquier.xyz> <20200306131547.GA2904@nol>
 <20200307014142.GC1531@paquier.xyz> <20200307061615.c47sju2bytuiaazv@nol>
 <8441.1583595994@sss.pgh.pa.us> <20200307205328.ffidfyo3me46qscn@nol>
 <15903.1583615371@sss.pgh.pa.us> <20200307211709.6kfpiddif4uxafg5@nol>
Comments: In-reply-to Julien Rouhaud <rjuju123@gmail.com>
	message dated "Sat, 07 Mar 2020 22:17:09 +0100"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <16529.1583616238.1@sss.pgh.pa.us>
Content-Transfer-Encoding: quoted-printable
Date: Sat, 07 Mar 2020 16:23:58 -0500
Message-ID: <16530.1583616238@sss.pgh.pa.us>
Precedence: bulk

Julien Rouhaud <rjuju123@gmail.com> writes:
> On Sat, Mar 07, 2020 at 04:09:31PM -0500, Tom Lane wrote:
>> Julien Rouhaud <rjuju123@gmail.com> writes:
>>> On Sat, Mar 07, 2020 at 10:46:34AM -0500, Tom Lane wrote:
>>>> What's the actual need that you're trying to deal with?

>>> Testing the correct behavior of non trivial commands, such as CIC/rein=
dex
>>> concurrently, that fails during the execution.

>> Hmm ... don't see how a timeout helps with that?

> For reindex concurrently, a SELECT FOR UPDATE on a different connection =
can
> ensure that the reindex will be stuck at some point, so canceling the co=
mmand
> after a long enough timeout reproduces the original faulty behavior.

Hmm, seems like a pretty arbitrary (and slow) way to test that.  I'd
envision testing that by setting up a case with an expression index
where the expression is designed to fail at some point partway through
the build -- say, with a divide-by-zero triggered by one of the tuples
to be indexed.

			regards, tom lane