On Tue, Jul 18, 2017 at 9:16 AM, Marina Polyakova <m.polyak...@postgrespro.ru> wrote: > Here I have made the 5th version of the patches. I have added the > precalculation of all primitive nodes that don't return set, are not > volatile themselves and their arguments are constant or precalculated > expressions too. There're regression tests for all of them and little notes > in the documentation. Like for the previous patches it seems that there is > no obvious performance degradation too on regular queries (according to > pgbench).
pgbench probably isn't a very good test for this sort of thing - it only issues very short-running queries where the cost of evaluating expressions is a relatively small part of the total cost. Even if things get worse, I'm not sure if you'd see it. I'm not sure exactly how you could construct a test case that could be harmed by this patch - I guess you'd want to initialize lots of CacheExprs but never make use of the caching usefully? It could also be useful to test things like TPC-H to see if you get an improvement. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
