* ... It's also possible that* we're acquiring a second or third lock type on a relation we have* already locked using
thefast-path, but for now we don't worry about* that case either.*/
How common is that case? There are only 16 entries in the fast path lock
table, so it seems like it would frequently fill up. So, if there are
common code paths that acquire different weak locks on the same
relation, then we might commonly miss a fast-path opportunity.
One path that acquires multiple weak locks is an INSERT INTO foo
SELECT ... FROM foo ...
Is that common enough to worry about?
Regards,Jeff Davis