On Thu, Mar 7, 2019 at 7:00 PM Andres Freund <and...@anarazel.de> wrote: > > On 2019-03-07 12:53:30 +0100, Tomas Vondra wrote: > > > > But then again, we could just > > hack a special version of ReadBuffer_common() which would just > > > (a) check if a page is in shared buffers, and if it is then consider the > > checksum correct (because in memory it may be stale, and it was read > > successfully so it was OK at that moment) > > > > (b) if it's not in shared buffers already, try reading it and verify the > > checksum, and then just evict it right away (not to spoil sb) > > This'd also make sense and make the whole process more efficient. OTOH, > it might actually be worthwhile to check the on-disk page even if > there's in-memory state. Unless IO is in progress the on-disk page > always should be valid.
Definitely. I already saw servers with all-frozen-read-only blocks popular enough to never get evicted in months, and then a minor upgrade / restart having catastrophic consequences.
