On Tue, Nov 28, 2017 at 1:36 PM, Feike Steenbergen <feikesteenber...@gmail.com> wrote: > On a server with a very frequent xid wraparound I can see that the > anti-wraparound vacuum is finished very quickly with the heap, yet it still > scans all the indexes, which causes it to still have to read a lot of data, > which takes a considerable amount of time. > > I dove into the code a bit and as far as I can tell, all the time spent for > doing this is is in lazy_cleanup_index. > > For the very specific use case of all-frozen, basically read-only tables, > would it be ok to skip the lazy_cleanup_index call? As we are sure we did > not touch the heap or the index, I'd say a cleanup may not be necessary.
There is a patch in the ongoing CF to do this: https://commitfest.postgresql.org/15/952/ It's a lot harder to do this correctly than it first appears. -- Peter Geoghegan
