Re: Slow update with simple query

Arnaud Lesauvage <thewild@freesurf.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