| From: | Tommi Maekitalo <t(dot)maekitalo(at)epgmbh(dot)de> |
|---|---|
| To: | Neil Conway <neilc(at)samurai(dot)com> |
| Cc: | <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: 1600 Column limit.. |
| Date: | 2002-11-15 10:24:42 |
| Message-ID: | 200211151124.42164.t.maekitalo@epgmbh.de |
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| Thread: | |
| Lists: | pgsql-general |
Hi,
Am Freitag, 15. November 2002 11:16 schrieb Neil Conway:
> Tommi Maekitalo <t(dot)maekitalo(at)epgmbh(dot)de> writes:
> > In a 1600 column table the database will do a linear search for data
> > in a row.
>
> Why's that?
>
> Cheers,
>
> Neil
one thing is to locate rows in a database. This is optimized and we can see
this in the query plan. But what does postgresql do, when he knows the row
and he should decide, which columns to send back? I'm not sure, but I would
suspect, that he just searches for columns with matching names. This can be
done with optimized access of systemtables, but the result are some
column-ids, which has to be located in the row.
Tommi
--
Dr. Eckhardt + Partner GmbH
http://www.epgmbh.de
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