| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Mark Wong <mark(at)2ndQuadrant(dot)com> |
| Cc: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>, Andrew Dunstan <andrew(dot)dunstan(at)2ndQuadrant(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Odd 9.4, 9.3 buildfarm failure on s390x |
| Date: | 2018-10-01 15:58:51 |
| Message-ID: | 3212.1538409531@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Mark Wong <mark(at)2ndQuadrant(dot)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
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