From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | "Matthias Karlsson" <matthias(at)yacc(dot)se> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Slow delete with with cascading foreign keys |
Date: | 2008-10-20 13:08:47 |
Message-ID: | 27718.1224508127@sss.pgh.pa.us |
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Lists: | pgsql-general |
"Matthias Karlsson" <matthias(at)yacc(dot)se> writes:
> I have a rather complex set of relations, connected with cascading
> foreign keys on delete. I'm experiencing very slow performance when
> deleting *the* lead node, which everything eventually depends on. The
> number of records ultimately to be deleted aren't that many (perhaps
> 2000-3000) but there are maybe 30 relations involved. I understand
> that this is most likely due to missing indices, but I have been
> unable to figure out how to get PostgreSQL to tell me where the
> performance bottleneck is.
If it's a reasonably modern PG version, EXPLAIN ANALYZE will break out
the time spent in each on-delete trigger, which should be enough to
answer the question.
regards, tom lane
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