Re: planner fails on HEAD

Pavel Stehule <pavel.stehule@gmail.com>

From: Pavel Stehule <pavel.stehule@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2011-12-04T22:52:41Z
Lists: pgsql-hackers
2011/12/4 Tom Lane <tgl@sss.pgh.pa.us>:
> Pavel Stehule <pavel.stehule@gmail.com> writes:
>> 2011/12/4 Tom Lane <tgl@sss.pgh.pa.us>:
>>> [ scratches head ... ]  Given that it got past the previous assertions,
>>> surely that ought to be impossible.  Could we see the values of
>>> cost_mergejoin's local variables, please?
>
>> It is strange
>
>> when I put a fprintf(stderr, "const literal") to exactly before or
>> somewhere after assertion, then assertion is ok. Without fprintf
>> assertion fails again
>
>> it looks like gcc bug - gcc 4.5.1 20100924 (Red Hat 4.5.1) It was
>> configured just with --enable-debug and --enable-cassert
>
> Hmm.  I'm betting that gcc has flushed one value to memory but the other
> one is still in a register that's wider than memory, creating a roundoff
> hazard.  Can you look at the generated assembly code?

I can, but tomorrow evening,

I'll send a code

Regards

Pavel
>
>                        regards, tom lane