Hi,
My application is getting the following exception:
InternalError: (psycopg2.InternalError) MultiXactId 808263738 has not been created yet -- apparent wraparound
I read over
https://www.postgresql.org/docs/9.6/routine-vacuuming.html#VACUUM-FOR-MULTIXACT-WRAPAROUND and I suspect the issue was caused by not vacuuming often enough. I can query the last_autovacuum time from the pg_stat_all_tables view. However, I found this in the documentation:
VACUUM uses the visibility map to determine which pages of a table must be scanned. Normally, it will skip pages that don't have any dead row versions even if those pages might still have row versions with old XID values. Therefore, normal VACUUMs won't always freeze every old row version in the table. Periodically, VACUUM will perform an aggressive vacuum, skipping only those pages which contain neither dead rows nor any unfrozen XID or MXID values. vacuum_freeze_table_age controls when VACUUM does that: all-visible but not all-frozen pages are scanned if the number of transactions that have passed since the last such scan is greater than vacuum_freeze_table_age minus vacuum_freeze_min_age. Setting vacuum_freeze_table_age to 0 forces VACUUM to use this more aggressive strategy for all scans.
How can I tell when the last "aggressive" auto-vacuum was performed? The vacuum_freeze_table_age parameter is at the default value (200000000).
I am using postgresql 9.6.
Thanks,
Mike
