Can anybody tell me why the following query requires a full table scan?
pgslekt=> explain select person_id, last_edit from persons
order by last_edit desc, person_id desc limit 50;
QUERY PLAN
-------------------------------------------------------------------------
Limit (cost=1495.03..1495.15 rows=50 width=8)
-> Sort (cost=1495.03..1535.54 rows=16204 width=8)
Sort Key: last_edit, person_id
-> Seq Scan on persons (cost=0.00..362.04 rows=16204 width=8)
(4 rows)
'persons' is a regular table where person_id is the primary
key. 'last_edit' is a regular date field. I've also tried:
pgslekt=> create index last_edit_key on persons(last_edit);
But that doesn't make any difference.
--
Leif Biberg Kristensen | Registered Linux User #338009
http://solumslekt.org/ | Cruising with Gentoo/KDE
My Jazz Jukebox: http://www.last.fm/user/leifbk/
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
