| From: | Matthew Wakeling <matthew(at)flymine(dot)org> |
|---|---|
| To: | hubert depesz lubaczewski <depesz(at)depesz(dot)com> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Postgres using more memory than it should |
| Date: | 2008-12-04 11:35:49 |
| Message-ID: | alpine.DEB.1.10.0812041132390.4666@aragorn.flymine.org |
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| Thread: | |
| Lists: | pgsql-performance |
On Wed, 3 Dec 2008, hubert depesz lubaczewski wrote:
> Check bug report from 2008-11-28, by Grzegorz Jaskiewicz:
> query failed, not enough memory on 8.3.5
>
> http://archives.postgresql.org/pgsql-bugs/2008-11/msg00180.php
Thanks, that does explain everything. So workmem is not a hard limit on
the amount of memory used per hash. Once the planner has committed to
using a hash (and it can only use estimates to work out whether it will
fit in workmem), then the execution will blindly go ahead and try and fit
absolutely everything in a hash in memory even if it doesn't fit in
workmem.
I agree it would be nice to fix this, but I'm not sure how at the moment.
Matthew
--
To most people, solutions mean finding the answers. But to chemists,
solutions are things that are still all mixed up.
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