Hi all, Thank you for your feedback. Please see the attached patch.
On Mon, Mar 23, 2026 at 4:30 AM Jakub Wartak <[email protected]> wrote: > On Sun, Mar 22, 2026 at 1:43 AM Bharath Rupireddy > <[email protected]> wrote: > > Hi, > > > On Sat, Mar 21, 2026 at 1:16 AM SATYANARAYANA NARLAPURAM > > <[email protected]> wrote: > > > > > > > While investigating a long recovery, I noticed that XLogPrefetch > stats were not logged at the end of recovery. This log message will be > useful to understand how effective XLogPrefetch was during recovery. Adding > a patch to address this. > > > > > > Applied this patch and validated the log message. This log message > appears to be useful to me, particularly while doing fleet wide analysis. > > > > > > 2026-03-20 23:33:13.756 PDT [2265441] LOG: XLogPrefetcher stats: > prefetch=14, hit=6, skip_init=5, skip_new=28, skip_fpw=18, skip_rep=996 > > > > This looks useful to understand how the prefetch helped during long > recoveries. > > > > > I am wondering if we can periodically log this in standby mode as > well, not just before promoting? > > > > Timer-based startup progress messaging allows logging such things > > (ereport_startup_progress API). There was an attempt to enable "redo > > in progress" for standbys, but that seemed to flood the standby logs > > even at the default progress interval of 10 sec. > > > > Having said that, the prefetcher stats could be added to the existing > > ereport_startup_progress("redo in progress xxx") message that works > > for crash recoveries—however, I don't prefer doing a bunch of atomic > > reads every progress interval of 10 sec. > > > Therefore, logging at the end of recovery looks good to me. > > +1 from me too to only of logging at the end of recovery (so -1 to logging > every now and then). If someone is interested in current state (or progress > over time) I think he can query pg_stat_recovery_prefetch view already, > even > today, right? > I reviewed the patch. I have the following comment: > > > > + elog(LOG, "XLogPrefetcher stats: prefetch=%lu, hit=%lu, > > skip_init=%lu, skip_new=%lu, skip_fpw=%lu, skip_rep=%lu", > > > > XLogPrefetcher is an internal data structure name, how about "redo > > prefetch stats: xxxx" to be consistent with other redo log messages? > > +1 > please find the attached patch addressing this. Regards, Lakshmi
0001-log-prefetch-stats-at-end-of-recovery.patch
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