On Sat, Apr 09, 2011 at 03:22:14PM +0200, Jesper Krogh wrote: > This seems like a place where there is room for improvement. > > 2011-04-09 15:18:08.016 testdb=# select id from test1 where id < 3 > order by id; > id > ---- > 1 > 2 > (2 rows) > > Time: 0.328 ms > 2011-04-09 15:18:11.936 testdb=# CREATE or Replace FUNCTION > testsort(id integer) returns integer as $$ BEGIN perform > pg_sleep(id); return id; END; $$ language plpgsql; > CREATE FUNCTION > Time: 12.349 ms > 2011-04-09 15:18:22.138 testdb=# select id from test1 where id < 3 > order by id,testsort(id); > id > ---- > 1 > 2 > (2 rows) > > Time: 3001.896 ms > > It seems strange that there is a need to evaluate testsort(id) at > all in this case.
How would PostgreSQL know that sorting by id leaves no ambiguity for the next key to address? Cheers, David. -- David Fetter <da...@fetter.org> http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fet...@gmail.com iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
