hubert depesz lubaczewski wrote: > 1. postgresql 8.2.4 > 2. system is 8-way xeon, 64bit with 32gram. > 3. autovacuum is (and was) turned off in configuration. > 4. today in peak hours autovacuum started. no mention of it in logs. it > just showed. started to vacuum the largest table in main database, and > brought the website down due to enormouos i/o.
ouch > > autovacuum is not properly configured because we dont use it - we do > nightly vacuumdb -azv, and we are positive that it did work (nagios > check for vacuumdb completion and possible errors). > > now - xid wraparound is not really a problem: > # select oid, age(datfrozenxid) from pg_database; > oid | age > ----------+----------- > 10819 | 158797276 > 7800493 | 158792051 > 19785040 | 158785318 > 1 | 158777444 > 10818 | 193463316 > 7805444 | 158776554 > 19812104 | 158767651 > 582103 | 212103362 > 19528166 | 212103362 > 7795500 | 212103362 > 7815547 | 212103362 > 19818144 | 212103362 > 19818149 | 212103362 > 6158349 | 212103362 > 19828634 | 212103362 > 4540444 | 212103362 > 19834405 | 212103362 > 7810585 | 212103362 > 19834438 | 212103362 > (19 rows) > > at the moment we are working at about 1500 transactions per second (when > autovac started it was around 1300). 1500 tps makes up for about 130M transactions per day which is fairly close in the ballpark of the default setting for autovacuum_freeze_max_age (200M). So if you say had a 30% increase in transactions on that day it could easily explain why autovacuum started automatically (or something prevented the former vacuum from doing its work). Stefan ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
