On Thu, Mar 11, 2021 at 11:13 AM Robert Haas <[email protected]> wrote: > On Thu, Mar 11, 2021 at 1:57 AM Michael Paquier <[email protected]> wrote: > > I think that this commit has some issues that need more thoughts. > > My biggest issue with this commit is that I can't understand from the > commit message why it's a bug fix that deserves to be back-patched. To > be honest, I can't even really understand whether it's a good idea in > master.
It is convoluted. The issue that led to my backpatching to 13 was tied to a 4% - 16% regression in an append-only workload by Mark Callaghan (he is well known as the main person behind MyRocks at Facebook): https://smalldatum.blogspot.com/2021/01/insert-benchmark-postgres-is-still.html Autovacuums driven by autovacuum_vacuum_insert_threshold scan indexes without receiving any benefit for it. Clearly vacuum_cleanup_index_scale_factor was misdesigned, but that only became a real problem with autovacuum_vacuum_insert_threshold. That did not seem acceptable to me. It'll get worse and worse as you add more and more indexes. -- Peter Geoghegan
