On 11 April 2018 at 03:14, Alvaro Herrera <alvhe...@alvh.no-ip.org> wrote: > 2. Do we want to revert Andrew's test stabilization patch? If I > understand correctly, the problem is the inverse of what was diagnosed: > "any running transaction at the time of the test could prevent pages > from being set as all-visible". That's correct, but the test doesn't > depend on pages being all-visible -- quite the contrary, it depends on > the pages NOT being all-visible (which is why the HeapFetches counts are > all non-zero). Since the pages contain very few tuples, autovacuum > should never process the tables anyway.
I think it's probably a good idea to revert it once the instrumentation is working correctly. It appears this found a bug in that code, so is probably useful to keep just in case something else breaks it in the future. I don't think there is too much risk of instability from other sources. There's no reason an auto-vacuum would trigger and cause a change in heap fetches. We only delete one row from lprt_a, that's not going to trigger an auto-vacuum. -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
