Adrian Klaver <adrian.klaver@aklaver.com> writes:
> On 1/16/24 09:45, Jim Vanns wrote:
>> I have a slow (CPU bound) DELETE statement I'm attempting to debug and I
>> suspect that its actually the ON DELETE CASCADE on the foreign key thats
>> causing it.
99% of the time, the cause is lack of an index on the foreign key's
referencing columns. We make you have a unique index on the
referenced columns, because otherwise the FK constraint's semantics
are unclear. But you're not required to make one on the other side.
>> What I need is a way to see into this statement as it executes to
>> confirm my suspicion - does anyone have any tips on that?
> Explain:
> https://www.postgresql.org/docs/current/sql-explain.html
Specifically, if EXPLAIN ANALYZE shows a lot of time spent in the
enforcement trigger for the FK, this is likely what's happening.
regards, tom lane
