On 17/12/16 23:04, Tom Lane wrote: > so that you don't need to use > SELECT DISTINCT? The sort/unique steps needed to do DISTINCT are > eating a large part of the runtime, Does a hash join result in a set of buckets that are then read out in order? It might, unless the sort method takes advantage of partially-sorted inout, be cheaper (by log(num-buckets)) to sort/uniq each bucket separately (and it would parallelize, too). -- Cheers, Jeremy -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
