Hi, On 2018-06-08 13:30:33 -0500, Jeremy Finzel wrote: > Avoid spuriously marking pages as all-visible (Dan Wood, Pavan Deolasee, > Álvaro Herrera) > > This could happen if some tuples were locked (but not deleted). While > queries would still function correctly, vacuum would normally ignore such > pages, with the long-term effect that the tuples were never frozen. In > recent releases this would eventually result in errors such as "found > multixact nnnnn from before relminmxid nnnnn". Oh, I already had forgotten about that one... It does sound like a likely explanation of your issue. Hard to tell without investigating a *lot* more closely than I realistically can do remotely. It seems quite possible to be the cause - I'd strongly suggest to upgrade to prevent further occurances, or at least exclude it as a cause. Greetings, Andres Freund