Re: Regression test failure in regression test temp.sql - Mailing list pgsql-hackers

From Michael Paquier
Subject Re: Regression test failure in regression test temp.sql
Date
Msg-id 20190809043456.GH3194@paquier.xyz
Whole thread Raw
In response to Re: Regression test failure in regression test temp.sql  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Regression test failure in regression test temp.sql  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On Wed, Aug 07, 2019 at 10:17:25AM -0400, Tom Lane wrote:
> Not objecting to the patch, exactly, just feeling like there's
> more here than meets the eye.  Not quite sure if it's worth
> investigating closer, or what we'd even need to do to do so.

Yes, something's weird here.  I'd think that the index only scan
ensures a proper ordering in this case, so it could be possible that a
different plan got selected here?  That would mean that the plan
selected would not be an index-only scan or an index scan.  So perhaps
that was a bitmap scan?

> BTW, I realize from looking at the plan that LIKE is interpreting the
> underscores as wildcards.  Maybe it's worth s/_/\_/ while you're

Right.  Looking around there are much more tests which have the same
problem.  This could become a problem if other tests running in
parallel use relation names with the same pattern, which is not a
issue as of HEAD, so I'd rather just back-patch the ORDER BY part of
it (temp.sql is the only test missing that).  What do you think about
the attached?
--
Michael

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