Tom Lane skrev:
"Matthias Karlsson" <matthias@xxxxxxx> 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
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