On Fri, Jul 16, 2010 at 22:29, Alex Hunsaker <bada...@gmail.com> wrote: > (FYI I do plan on doing some performance testing with large columns > later, any other requests?)
And here are the results. All tests are with an empty table with 1500 int4 columns. There is a unique non null index on the first column. (non assert build) A: select count(1) from (select * from test group by ...1500 columns...) as res; B: select count(1) from (select * from test group by a_0) as res; -- a_0 has the not null unique index CVS A: 360ms PATCH A: 370ms PATCH B: 60ms 1500 indexes (one per column, on the column): CVS: A: 670ms PATCH A: 850ms PATCH B: 561ms So it seems for tables with lots of columns the patch is faster, at least when you omit all the columns from the group by. I suspect for most "normal" (5-20 columns) usage it should be a wash. (Stupid question) Does anyone know why HEAD is quite a bit slower when there are lots off indexes? Do we end up looping and perhaps locking them or something? -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
