On Wed, Sep 14, 2011 at 6:50 AM, MirrorX <mirr...@gmail.com> wrote: > dear all, > > i have a table with (approx) 500.000.000 rows. it has several indexes, one > of which is a multicolumn index > for a column that has an id (integer) and a column that has a timestamp. i > have read in the manual that the multicolumn index can be used only if the > clauses of the query are in the same order as the columns of the index. so i > am trying the following simple query ->
this is incorrect. Where did you read this? The order in the where clause doesn't matter. Older versions of pg cannot use a muilticolumn index unless you use the first column in the where clause / group by, but newer versions can use that index, but since it's much less efficient that way they will usually pick another index with the other column in it first. -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
