On Mon, May 8, 2017 at 4:24 PM, Vincent Veyron <vv.li...@wanadoo.fr> wrote: > On Mon, 8 May 2017 12:48:29 -0600 > Scott Marlowe <scott.marl...@gmail.com> wrote: > > Hi Scott, > > Thank you for your input. > >> >> The most likely cause of the difference would be that one server IS >> honoring fsync requests from the db and the other one isn't. >> >> If you run pgbench on both (something simple like pgbench -c 1 -T 60, >> aka one thread for 60 seconds) on a machine running on a 7200RPM hard >> drive, you should get approximately 120 transactions per second > > Here are the results : > > #Kimsufi > pgbench -c 1 -T 60 test > starting vacuum...end. > transaction type: TPC-B (sort of) > scaling factor: 1 > query mode: simple > number of clients: 1 > number of threads: 1 > duration: 60 s > number of transactions actually processed: 6618 > latency average: 9.069 ms > tps = 110.270771 (including connections establishing) > tps = 110.283733 (excluding connections establishing)
Just under 120, looks like fsync is working. > > #Online > starting vacuum...end. > transaction type: TPC-B (sort of) > scaling factor: 1 > query mode: simple > number of clients: 1 > number of threads: 1 > duration: 60 s > number of transactions actually processed: 1150 > latency average: 52.317 ms > tps = 19.114403 (including connections establishing) > tps = 19.115739 (excluding connections establishing) OK that's horrendous. My mobile phone is likely faster. We need to figure out why it's so slow. If it's in a RAID-1 set it might be syncing. >> > -Why are regular queries much faster on this same server? >> >> That's a whole nother subject. Most likely the faster machine can fit >> the whole db in memory, or has much faster memory, or the whole >> dataset is cached etc etc. >> > > The dataset is small (35 MB) and both servers have 4GB memory. It appears to > be faster on the Online server. Yeah it fits in memory. Select queries will only hit disk at bootup. First machine SNIP > Speed: 1066 MHz SNIP > Configured Clock Speed: 1066 MHz Second machine > Speed: 1600 MHz SNIP > Configured Clock Speed: 1333 MHz Yeah the second machine likely has a noticeably faster CPU than the first as well. It's about two years younger so yeah it's probably just cpu/mem that's making it fast. -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
