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Re: Odd 9.4, 9.3 buildfarm failure on s390x

Andrew Gierth <andrew@tao11.riddles.org.uk>

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From: Andrew Gierth <andrew@tao11.riddles.org.uk>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>, Mark Wong <mark@2ndquadrant.com>, Andres Freund <andres@anarazel.de>, pgsql-hackers@postgresql.org
Date: 2018-09-30T03:52:41Z
Lists: pgsql-hackers 
>>>>> "Tom" == Tom Lane <tgl@sss.pgh.pa.us> writes:

 > Andrew Gierth <andrew@tao11.riddles.org.uk> writes:
 >> Because int being more than 32 bits is the simplest explanation for
 >> this difference.

 Tom> Curious to hear your reasoning behind that statement? I hadn't
 Tom> gotten further than "memcmp is broken" ... and neither of those
 Tom> theories is tenable, because if they were true then a lot more
 Tom> things besides uuid sorting would be falling over.

memcmp() returns an int, and guarantees only the sign of the result, so
((int32) memcmp()) may have the wrong value if int is wider than int32.

But yeah, it seems unlikely that it would break for uuid but not bytea
(or text in collate C).

-- 
Andrew (irc:RhodiumToad)

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.