Re: Slow delete with with cascading foreign keys

"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