On Tue, Jun 21, 2022 at 3:18 PM Andrey Borodin <x4...@yandex-team.ru> wrote: > > > On 21 Jun 2022, at 12:35, Amit Kapila <amit.kapil...@gmail.com> wrote: > > > > I wonder if the newly introduced "recovery_prefetch" [1] for PG-15 can > > help your case? > > AFAICS recovery_prefetch tries to prefetch main fork, but does not try to > prefetch WAL itself before reading it. Kirill is trying to solve the problem > of reading WAL segments that are our of OS page cache. >
Okay, but normally the WAL written by walreceiver is read by the startup process soon after it's written as indicated in code comments (get_sync_bit()). So, what is causing the delay here which makes the startup process perform physical reads? -- With Regards, Amit Kapila.
