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Re: Segfault manifesting in libm from cost_sort

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Andrew Badr" <andrewbadr(at)gmail(dot)com>
Cc: "John R Pierce" <pierce(at)hogranch(dot)com>, pgsql-bugs(at)postgresql(dot)org
Subject: Re: Segfault manifesting in libm from cost_sort
Date: 2008-07-30 14:42:38
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-bugs
"Andrew Badr" <andrewbadr(at)gmail(dot)com> writes:
> ECC memory, RAID 10 w/ adaptec 3405 hardware controller. Period between
> crashes ranged from about 1min-5mins. Just switched to a new box so the
> problem is "gone". In the original email I meant ubuntu 6.06.

Well, that could mean it's a hardware problem.  Or it could be a libm
problem --- is the new box running exactly the same system software?

The third likely possibility is that cost_sort() is passing some invalid
value to log(), and you're not seeing that happen on the new box because
of slightly different statistics or some such.  This would still imply
a bug in libm --- it shouldn't be possible to make log segfault --- but
there could also be a corner case that cost_sort is mishandling.

If you can still reproduce the problem on the old box, please rebuild
Postgres with --enable-debug, and/or put some debug logging into
cost_sort to see what it's passing to log(), and see what you can learn.

			regards, tom lane

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