On Wed, Aug 5, 2009 at 8:50 PM, Ip Wing Kin John<wkipjohn@xxxxxxxxx> wrote: > I have a database (699221). It contains of 1.8GB data (707710). I am > doing a complex query. Which required to load a 80MB index (732287). > > I restarted Postgresql so the cache is empty and it has to read the > table and index from disk. Which I understand is an expensive process. > But what I don't understand is even I split the index into a different > tablespace located on a completely separate disk (mounted on /hdd2) > there is still a very long I/O wait time. That index is only thing > exist on that disk. Any idea why? Or any way I can find out what it is > waiting for? Thanks. OK before DTrace, did you run explain analyze on the query? I think the output of that would be interesting. Looking at the DTrace output it looks to me like you're reading at least one > 1GB table. since you're accessing a file with a .1 on it. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
