On Thu, 26 Dec 2024 13:15:59 +0900 torikoshia <torikos...@oss.nttdata.com> wrote:
> On 2024-12-25 00:52, Tom Lane wrote: > > torikoshia <torikos...@oss.nttdata.com> writes: > >> I have attached a PoC patch that modifies EXPLAIN to include page > >> fault > >> information during both the planning and execution phases of a > >> query. > > > > Surely these numbers would be too unstable to be worth anything. > > Thanks for your comment! > > Hmm, I didn't know these are unstable. If there are any reasons, I'd > like to know about them. > > I would like to explore alternative methods for measuring resource > usage, but > I am not aware of other approaches. > (IIUC pg_stat_kcache[1], which is said to provide information about > filesystem layer I/O usage also gets metrics from getrusage(2)) What I'd really like to see is a column added to pg_stat_database called blks_read_majflts It would be great if we could calculate a cache hit ratio that took OS major page faults into account Yes this could also be done in pg_stat_kcache but why not do it right in pg_stat_database? I think it would pretty widely appreciated and used. -Jeremy
