On Sun, Nov 27, 2005 at 11:38:57PM +1100, Brendan Jurd wrote: > > Already done in 8.1. Here's an excerpt from the Release Notes: > > > > Automatically use indexes for MIN() and MAX() (Tom) > > > > In previous releases, the only way to use an index for MIN() > > or MAX() was to rewrite the query as SELECT col FROM tab ORDER > > BY col LIMIT 1. Index usage now happens automatically. > > > > Which query form will generally be faster in 8.1 (or will they be > exactly the same)?
They'll effectively be the same: stats=# explain select id from stats_participant where id is not null order by id limit 1; QUERY PLAN ----------------------------------------------------------------------------------------------------------------- Limit (cost=0.00..3.40 rows=1 width=4) -> Index Scan using stats_participant_pkey on stats_participant (cost=0.00..1486391.76 rows=436912 width=4) Filter: (id IS NOT NULL) (3 rows) stats=# explain select min(id) from stats_participant; QUERY PLAN ------------------------------------------------------------------------------------------------------------------------- Result (cost=3.40..3.41 rows=1 width=0) InitPlan -> Limit (cost=0.00..3.40 rows=1 width=4) -> Index Scan using stats_participant_pkey on stats_participant (cost=0.00..1486391.76 rows=436912 width=4) Filter: (id IS NOT NULL) (5 rows) stats=# -- Jim C. Nasby, Sr. Engineering Consultant [EMAIL PROTECTED] Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org