Harald Armin Massa wrote: > Alvaro, > > > How many database-wide vacuums did you run during these 9 months? I'm > > smelling transaction Id wraparound in pg_class or some other system > > catalog. > > "database wide" vacuums have been very very seldom; I fear the only one was > at initial db bulk load. at the moment I am on a way to upgrade to 8.1, with > autovacuum enabled ... so in the long run THAT possible reason should > vanish. > > And I understand correctly that your suspicion is: file gets killed because > of transaction id wraparound in system table?
No, the file doesn't get killed, but an old tuple on the pg_class system catalog magically appears because it was deleted and marked with a very old Xmax, that after the wraparound is seen as future; and thus the tuple that was deleted is suddenly visible. For this to happen you need to have failed to vacuum pg_class in a very long time. There may be other explanations, but we'd need more data, like how much tuples for that table you got on pg_class and what do they look like. Try something like set enable_indexscan to off; select xmin, xmax, relname from pg_class where relname = 'the table'; You can search the archives using http://www.pgsql.ru -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc. ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
