Re: slow query : very simple delete, 100% cpu, nearly no disk activity

On Friday 11 September 2009 23:30:37 Robert Haas wrote:
> On Mon, Sep 7, 2009 at 5:05 AM, Vincent de Phily
> <vincent(dot)dephily(at)mobile-devices(dot)fr> wrote:
> > On Monday 07 September 2009 03:25:23 Tom Lane wrote:
> >>
> >> 99% of the time, the reason a delete takes way longer than it seems like
> >> it should is trigger firing time.  In particular, foreign key triggers
> >> where you don't have an index on the referencing column.  Are there
> >> any foreign keys linking to this table?
> >
> > Yes, but they look fine to me (?). Only one FK references the table; it's
> > an internal reference :
> >
(...)
> I would try EXPLAIN ANALYZE DELETE ... with a query that is modified
> so as to delete only a handful of rows. That will report the amount
> of time spent in triggers vs. the main query, which will help you
> assess whether your conclusion that the foreign keys are OK is
> correct.

Good idea. I'll try that in a little while and report the result.

--
Vincent de Phily
Mobile Devices
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