On 14/11/14 14:54, Tom Lane wrote: > Jeremy Harris <j...@wizmail.org> writes: >> On 14/11/14 00:46, Simon Riggs wrote: >>> Limit (cost=.... rows=20 width=175) (actual time=.... rows=20 loops=1) >>> -> Sort (cost=.... rows=568733 width=175) (actual time=.... >>> rows=20 loops=1) >>> Sort Method: top-N heapsort > >> Going off on a tangent, when I was playing with a merge-sort >> implementation I propagated limit information into the sort >> node, for a significant win. > > I'm not entirely following. The top-N heapsort approach already > makes use of the limit info.
Having gone back to look, you're right. It was Uniq nodes I merged (the sort handles both bounded-output and dedup). -- Cheers, Jeremy -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers