From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <david.rowley@2ndquadrant.com>
cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Reducing the runtime of the core regression tests
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Comments: In-reply-to David Rowley <david.rowley@2ndquadrant.com>
	message dated "Thu, 11 Apr 2019 12:27:20 +1200"
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Date: Thu, 11 Apr 2019 00:44:02 -0400
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David Rowley <david.rowley@2ndquadrant.com> writes:
> I was surprised to see nothing mentioned about attempting to roughly
> sort the test order in each parallel group according to their runtime.

I'm confused about what you have in mind here?  I'm pretty sure pg_regress
launches all the scripts in a group at the same time, so that just
rearranging the order they're listed in on the schedule line shouldn't
make any noticeable difference.  If you meant changing the order of
operations within each script, I don't really want to go there.
It'd require careful per-script analysis, and to the extent that the
existing tests have some meaningful ordering (admittedly, many don't),
we'd lose that.

>> Thoughts?  Anyone object to making these sorts of changes
>> post-feature-freeze?

> I think it's a good time to do this sort of thing.  It should be
> easier to differentiate tests destabilising due to this change out
> from the noise of other changes that are going in.... since currently,
> the rate of those other changes should not be very high. Doing it any
> later in the freeze does not seem better since we might discover some
> things that need to be fixed due to this.

Yeah.  I wouldn't propose pushing this in shortly before beta, but
if we do it now then we've probably got a month to sort out any
problems that may appear.

			regards, tom lane