On Wed, Sep 05, 2007 at 12:30:21PM +0100, Gregory Stark wrote: > SELECT DISTINCT ON (id) id, the_date AS min_date FROM my_table ORDER BY id, > the_date ASC > SELECT DISTINCT ON (id) id, the_date AS max_date FROM my_table ORDER BY id, > the_date DESC > I think the first of these can actually use your index but the latter can't > unless you create one for it specifically (which is not so easy -- it'll be > easier in 8.3 though). Worse, I'm not really sure it'll be any faster than the > query you already have.
it's easy to fix the second query (fix to use index) - just change order by to: order by id desc, the_date desc. depesz -- quicksil1er: "postgres is excellent, but like any DB it requires a highly paid DBA. here's my CV!" :) http://www.depesz.com/ - blog dla ciebie (i moje CV) ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
