Re: WIP: WAL prefetch (another approach)

On Sat, Apr 10, 2021 at 08:27:42AM +1200, Thomas Munro wrote:
> On Fri, Apr 9, 2021 at 3:37 PM Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:
> > Here's some little language fixes.
>
> Thanks! Done. I rewrote the gibberish comment that made you say
> "XXX: what?". Pushed.
>
> > BTW, before beginning "recovery", PG syncs all the data dirs.
> > This can be slow, and it seems like the slowness is frequently due to file
> > metadata. For example, that's an obvious consequence of an OS crash, after
> > which the page cache is empty. I've made a habit of running find /zfs -ls |wc
> > to pre-warm it, which can take a little bit, but then the recovery process
> > starts moments later. I don't have any timing measurements, but I expect that
> > starting to stat() all data files as soon as possible would be a win.
>
> Did you see commit 61752afb, "Provide
> recovery_init_sync_method=syncfs"? Actually I believe it's safe to
> skip that phase completely and do a tiny bit more work during
> recovery, which I'd like to work on for v15[1].

Yes, I have it in my list for v14 deployment. Thanks for that.

Did you see this?
https://www.postgresql.org/message-id/GV0P278MB0483490FEAC879DCA5ED583DD2739%40GV0P278MB0483.CHEP278.PROD.OUTLOOK.COM

I meant to mail you so you could include it in the same commit, but forgot
until now.

--
Justin