Re: Avoid Wraparound Failures

On 3/25/22 17:16, Loles wrote:

Hi!

Suppose the databases on my instance are near to have a wraparound failure.

Is this actually the case, or are you just afraid?

(I think so, from what I see, but in the PostgreSQL log I haven't seen any warning about It yet).

What do I have to do?

vacuum freeze;

Kinda, but really... Heck No!!!

vacuum --freeze --jobs=`nproc` --dbname=your_db_name

That will VACUUM FREEZE every table in your database in multiple threads.

However, you only need to freeze tables getting near wraparound.  pg_class.relfrozenxid tells you which tables to worry about.

better than,

vacuum analyze;

VACUUM ANALYZE does a plain vacuum plus collects statistics for the query analyzer.  Collecting query stats has nothing to do with vacuuming or protecting against wraparound.

Or both?

If the autovacuum_freeze configuration parameters have defaults values, should I modify any first?

What version are you running?  Even the recently EOL versions protect from wraparound (though it's a painful last-ditch process).