On Sun, 2007-07-22 at 08:53 -0700, Josh Berkus wrote: > Pavel Stehule wrote: > > Hello, > > > > I checked my tests again I have different results. Now I tested > > PostgreSQL on dedicated server. Now 8.3 is about 20% faster. I didn't > > see strong impression of autovacuum. All numbers are approximate > > only. I did pgbench 3x for folowing configuration: (autovacuum on, > > autovacuum off, statistics off) and for -tntransaction (100, 1000, > > 4000) > > In other news, 8.3 with current HOT is 13% faster than 8.2 at TPCE in > the first 1/2 hour. Performance does not fall over 5 hours of test run, > and most of the main tables never have autovacuum triggered at all. > Unfortnately, we don't yet have a 5-hour 8.2 run to compare > last-half-hour performance.
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I think the rule of thumb is if the workload doesn't have enough UPDATEs to trigger VACUUMs then HOT will have a low benefit. With any workload, we should run it *until* we see some autovacuums kick-in, so we can compare the overall situation of HOT v non-HOT. HOT is designed for longer term benefit; fillfactor benefits fade over time (as defined). -- Simon Riggs EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
