On Mon, May 17, 2010 at 2:06 AM, Piotr Legiecki <piotrlg@xxxxxxxxxx> wrote: > 2. select count(*) from some_table; runs in a fraction of a second on the > console on both servers (there are only 4000 records, the second longer > table has 50000 but it does not matter very much). From pg_admin the results > are: > - slow server (and the longest table in my db) 938ms (first run) and about > 40ms next ones > - fast server 110ms first run, about 30ms next ones. > Well, finally my new server deservers its name ;-) The later times as I > understand are just cache readings from postgresql itself? SNIP > So the server itself seems faster. > So still I don't get this: select * from table; on old server takes 0,5 sec, > on new one takes 6sec. Why there is so big difference? And it does not > matter how good or bad select is to measure performance, because I don't > measure the performance, I measure the relative difference. Somwhere there > is a bottleneck. Yep, the network I'd say. How fast are things like scp between the various machines? > 4. Machine. The new server has 5 SAS disks (+ 1 spare), but I don't remember > how they are set up now (looks like mirror for system '/' and RAID5 for rest > - including DB). size of the DB is 405MB Get off of RAID-5 if possible. A 3 Disk RAID-5 is the slowest possible combination for RAID-5 and RAID-5 is generally the poorest choice for a db server. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
