On Fri, Apr 1, 2022 at 2:27 PM Peter Geoghegan <p...@bowt.ie> wrote: > I'm not following. It seems like you're saying that the ability to > vacuum indexes on their own schedule (based on their own needs) is not > sufficiently compelling. I think it's very compelling, with enough > indexes (and maybe not very many). > > The conveyor belt doesn't just save I/O from repeated scanning of the > heap. It may also save on repeated pruning (or just dirtying) of the > same heap pages again and again, for very little benefit.
I'm also not following. In order to get that benefit, we would have to sometimes decide to not perform lazy_scan_heap() at the startup of a vacuum. And in this email I asked you whether it was your idea that we should always start a vacuum operation with lazy_scan_heap(), and you said "yes": http://postgr.es/m/ca+tgmoa6kveeurtyeoi3a+ra2xuynwqmj_s-h4kun6-bkmm...@mail.gmail.com So I'm completely confused here. If we always start a vacuum with lazy_scan_heap(), as you said you wanted, then we will not save any heap scanning. What am I missing? -- Robert Haas EDB: http://www.enterprisedb.com