On Wed, 24 Jul 2002, Daryl Herzmann wrote: [lots of chopping and rearranging...] > snet=# explain analyze select * from t2002_06 WHERE station = 'SAMI4'; > Seq Scan on t2002_06 (cost=0.00..35379.69) > Total runtime: 2452.14 msec > > snet=# set enable_seqscan=off; > snet=# explain analyze select * from t2002_06 WHERE station = 'SAMI4'; > Index Scan using t2002_06_station_hash_idx on t2002_06 > (cost=0.00..132190.93) > Total runtime: 325.22 msec
I don't know how these indexes actually work, but just looking at the numbers here, it uses a seq scan because it thinks a seq scan costs far less than an index scan (35379 v 132190) even though the actual runtime is much less for the index scan (2452 msec v 325 msec). *why* it's guessing wrong, I haven't got a clue. =) -- Phil Davey Computer Officer Hughes Hall College, Cambridge Email [EMAIL PROTECTED] ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
