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Re: Odd 9.4, 9.3 buildfarm failure on s390x

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mark Wong <mark@2ndQuadrant.com>
Cc: Andrew Gierth <andrew@tao11.riddles.org.uk>, Andrew Dunstan <andrew.dunstan@2ndQuadrant.com>, Andres Freund <andres@anarazel.de>, pgsql-hackers@postgresql.org
Date: 2018-10-01T15:58:51Z
Lists: pgsql-hackers 
Mark Wong <mark@2ndQuadrant.com> writes:
>                   a                   |                  a                   |  uuid_cmp
> --------------------------------------+--------------------------------------+-------------
>  11111111-1111-1111-1111-111111111111 | 11111111-1111-1111-1111-111111111111 |           0
>  11111111-1111-1111-1111-111111111111 | 22222222-2222-2222-2222-222222222222 | -2147483648
>  11111111-1111-1111-1111-111111111111 | 3f3e3c3b-3a30-3938-3736-353433a2313e | -2147483648
>  22222222-2222-2222-2222-222222222222 | 11111111-1111-1111-1111-111111111111 |           1
>  22222222-2222-2222-2222-222222222222 | 22222222-2222-2222-2222-222222222222 |           0
>  22222222-2222-2222-2222-222222222222 | 3f3e3c3b-3a30-3938-3736-353433a2313e | -2147483648
>  3f3e3c3b-3a30-3938-3736-353433a2313e | 11111111-1111-1111-1111-111111111111 |           1
>  3f3e3c3b-3a30-3938-3736-353433a2313e | 22222222-2222-2222-2222-222222222222 |           1
>  3f3e3c3b-3a30-3938-3736-353433a2313e | 3f3e3c3b-3a30-3938-3736-353433a2313e |           0
> (9 rows)


Oooh ... apparently, on that platform, memcmp() is willing to produce
INT_MIN in some cases.  That's not a safe value for a sort comparator
to produce --- we explicitly say that somewhere, IIRC.  I think we
implement DESC by negating the comparator's result, which explains
why only the DESC case fails.

			regards, tom lane

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Allow btree comparison functions to return INT_MIN.