On Thu, Nov 2, 2017 at 8:01 AM, Craig Ringer <cr...@2ndquadrant.com> wrote: > That forces materialization, and I'm guessing part of Tomas's goal > here is to prevent the need to materialize into a temp table / > tuplestore / etc.
I get that, but if you're running a query like "SELECT * FROM bigtable", you don't need parallel query in the first place, because a single backend is quite capable of sending back the rows as fast as a client can read them. If you're running a query like "SELECT * FROM bigtable WHERE <highly selective predicate>" then that's a good use case for parallel query, but then materializing it isn't that bad because the result set is a lot smaller than the original table. I am not disputing the idea that there are *some* cases where parallel query is useful and materialization is still undesirable, of course. -- 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
