Fujii Masao escribió: > Hi, > > In HEAD, when autovacuum is disabled, autovacuum process is not > launched forcibly to prevent XID wraparound even if we go through > autovacuum_freeze_max_age. This seems to be because > ShmemVariableCache->xidVacLimit is not initialized (i.e., > SetTransactionIdLimit() is not called) until VACUUM is performed. > > OTOH, in older version, ShmemVariableCache->xidVacLimit is always > initialized when backend updates the flat database file, and then > autovacuum process seems to be launched forcibly as expected.
Hmm. Yeah, this is a serious problem. The only caller of SetTransactionIdLimit is now vac_truncate_clog. We need another one, but where? For a moment I thought about adding one to autovacuum launcher's initialization, but what if it's disabled? Maybe check at backend startup whether the limit is valid, and call SetTransactionIdLimit if not? Related commit history: the call to update the xid limit was removed here: http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=186b10c1f0a61f90d320a4ccce2ff8b31fa55210 which introduced a function TransactionIdLimitIsValid which could presumably have been used as I propose above. However, it was taken out in http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=1a7bbfe645b8379e368ec9969f99fee455e3ecf3 -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
