Re: Slow delete with with cascading foreign keys

Tom Lane skrev:
> "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

Thanks, that gave me something to work with. I targeted the triggers that had the most "uses", but it did not seem to
help that much. I managed to reduce execution time with maybe 10-15%, but I'll try to apply indices more aggressively to
see if it helps.

// Matthias