Re: Performance of aggregates over set-returning functions

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "John Smith" <sodgodofall(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Performance of aggregates over set-returning functions
Date: 2008-06-10 00:17:24
Message-ID: 2322.1213057044@sss.pgh.pa.us
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"John Smith" <sodgodofall(at)gmail(dot)com> writes:
> Sorry for the long delay in following up on this suggestion. The
> change Tom suggested fixed the performance problems I was seeing, but
> I never ran the full regression suite on the modified code, as
> everything in my performance tests seemed to indicate the bug was
> fixed (i.e, no errors even with --cassert-enabled). When I recently
> ran the regression suite on the "fixed" version of Postgres, the
> "misc" test suite fails with the following error message: "ERROR:
> cache lookup failed for type 2139062143". Is this a manifestation of
> the problem where certain items are being freed too early?

Yup --- something's trying to use memory that's already been freed.
The particular case is evidently a field containing a type OID.

You might be able to get a clue where the problem is by getting a gdb
stack trace back from errfinish(), but this sort of kills my optimism
that the 7.0-era problem is gone ...

regards, tom lane

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