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Hi,
We run postgres 9.4.5.
Starting this morning, we started seeing messages like the below:
Oct 12 14:07:15 site-db01a postgres[11253]: [106430-1] app=,user=,db=,ip=LOG: MultiXact member wraparound protections are disabled because oldest checkpointed MultiXact 1 does not exist on disk
Oct 12 14:09:26 site-db01a postgres[11253]: [106526-1] app=,user=,db=,ip=LOG: MultiXact member wraparound protections are disabled because oldest checkpointed MultiXact 1 does not exist on disk
Oct 12 14:14:18 site-db01a postgres[11253]: [106608-1] app=,user=,db=,ip=LOG: MultiXact member wraparound protections are disabled because oldest checkpointed MultiXact 1 does not exist on disk
Our autovacuum_freeze_max_age = 1750000000.
site=# SELECT datname, age(datfrozenxid) FROM pg_database;
datname | age -----------+------------ site | 1645328344 template0 | 1274558807 bench | 1274558807 postgres | 1324283514 template1 | 1274558807 So we’re about 100 mil transactions away before we start vacuuming to prevent wraparound.
We’re running precautionary vacuums on our largest offenders to try and drop our transaction ids
What I’d request some clarity on is the message above. What does it mean that "oldest
checkpointed MultiXact does not exist on disk”? Would we lose data if we did have to wrap around?
Is this telling us we’re not vacuuming effectively enough?
Thanks,
Karthik
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