| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Arnaud Lesauvage <thewild(at)freesurf(dot)fr> |
| Cc: | Ragnar <gnari(at)hive(dot)is>, Jens Schipkowski <jens(dot)schipkowski(at)apus(dot)co(dot)at>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Slow update with simple query |
| Date: | 2006-12-14 16:19:00 |
| Message-ID: | 21233.1166113140@sss.pgh.pa.us |
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| Lists: | pgsql-performance |
Arnaud Lesauvage <thewild(at)freesurf(dot)fr> writes:
> Tom Lane a crit :
>> It seems the time must be going into this trigger function. What
>> does it do?
> A lot of things ! Indeed, if it runs it will very badly hurt performances (table
> lookups, string manipulation, etc...) !
> But it should only be tringered on INSERTs, and I am doing an UPDATE !
Doh, right, I obviously still need to ingest more caffeine this morning.
I think the conclusion must be that there was just too much I/O to be
done to update all the rows. Have you done any tuning of shared_buffers
and so forth? I recall having seen cases where update performance went
bad as soon as the upper levels of a large index no longer fit into
shared_buffers ...
regards, tom lane
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