> Perhaps Nitin was thinking of a scenario in which WAL hits are counted > as hits on the same IOObject as shared buffer hits. Since this thread > has been going on for awhile and we haven't recently had a schema > overview, I could understand if there was some confusion
Yes. I was considering a scenario where WAL hits are counted as hits on the same IOObject as shared buffer hits. > For clarity, > I will restate that the current proposal is to count WAL buffer hits > for IOObject WAL, which means they will not be mixed in with shared > buffer hits. > > And I think it makes sense to count WAL IOObject hits since increasing > wal_buffers can lead to more hits, right? Thank you for the clarification. I agree with the proposal to count WAL buffer hits for IOObject WAL separately from shared buffer hits. This distinction will provide a more accurate representation. Best Regards, Nitin Jadhav Azure Database for PostgreSQL Microsoft On Mon, Jun 17, 2024 at 8:23 PM Melanie Plageman <melanieplage...@gmail.com> wrote: > > On Thu, Jun 13, 2024 at 5:24 AM Nazir Bilal Yavuz <byavu...@gmail.com> wrote: > > > > On Sun, 9 Jun 2024 at 18:05, Nitin Jadhav <nitinjadhavpostg...@gmail.com> > > wrote: > > > > > > > If possible, let's have all the I/O stats (even for WAL) in > > > > pg_stat_io. Can't we show the WAL data we get from buffers in the hits > > > > column and then have read_bytes or something like that to know the > > > > amount of data read? > > > > > > The ‘hits’ column in ‘pg_stat_io’ is a vital indicator for adjusting a > > > database. It signifies the count of cache hits, or in other words, the > > > instances where data was located in the ‘shared_buffers’. As a result, > > > keeping an eye on the ‘hits’ column in ‘pg_stat_io’ can offer useful > > > knowledge about the buffer cache’s efficiency and assist users in > > > making educated choices when fine-tuning their database. However, if > > > we include the hit count of WAL buffers in this, it may lead to > > > misleading interpretations for database tuning. If there’s something > > > I’ve overlooked that’s already been discussed, please feel free to > > > correct me. > > > > I think counting them as a hit makes sense. We read data from WAL > > buffers instead of reading them from disk. And, WAL buffers are stored > > in shared memory so I believe they can be counted as hits in the > > shared buffers. Could you please explain how this change can 'lead to > > misleading interpretations for database tuning' a bit more? > > Perhaps Nitin was thinking of a scenario in which WAL hits are counted > as hits on the same IOObject as shared buffer hits. Since this thread > has been going on for awhile and we haven't recently had a schema > overview, I could understand if there was some confusion. For clarity, > I will restate that the current proposal is to count WAL buffer hits > for IOObject WAL, which means they will not be mixed in with shared > buffer hits. > > And I think it makes sense to count WAL IOObject hits since increasing > wal_buffers can lead to more hits, right? > > - Melanie
