Hi, On 2021-12-09 16:34:53 -0800, Peter Geoghegan wrote: > But even still, why not have some variant of single-user mode just for > this task?
> Something that's easy to use when the DBA is rudely > awakened at 4am -- something a little bit like a big red button that > fixes the exact problem of XID exhaustion, in a reasonably targeted > way? I don't think that this needs to involve the VACUUM command > itself. I think we should move *away* from single user mode, rather than the opposite. It's a substantial code burden and it's hard to use. I don't think single user mode is a good fit for this anyway - it's inherently focussed on connecting to a single database. But wraparound issues often involve more than one database (often just because of shared catalogs). Also, requiring a restart will often exascerbate the problem - the cache will be cold, there's no walwriter, etc, making the vacuum slower. Making vacuum not consume an xid seems like a lot more promising - and quite doable. Then there's no need to restart at all. Greetings, Andres Freund
