Re: fdatasync performance problem with large number of DB files

From: Thomas Munro <thomas(dot)munro(at)gmail(dot)com>
To: Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com>
Cc: Bruce Momjian <bruce(at)momjian(dot)us>, Paul Guo <guopa(at)vmware(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Michael Brown <michael(dot)brown(at)discourse(dot)org>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: fdatasync performance problem with large number of DB files
Date: 2021-03-19 05:28:46
Message-ID: CA+hUKGKgj+SN6z91nVmOmTv2KYrG7VnAGdTkWdSjbOPghdtooQ@mail.gmail.com
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On Fri, Mar 19, 2021 at 3:23 PM Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
> Thanks for updating the patch! It looks good to me!
> I have one minor comment for the patch.
>
> + elog(LOG, "could not open %s: %m", path);
> + return;
> + }
> + if (syncfs(fd) < 0)
> + elog(LOG, "could not sync filesystem for \"%s\": %m", path);
>
> Since these are neither internal errors nor low-level debug messages, ereport() should be used for them rather than elog()? For example,

Fixed.

I'll let this sit until tomorrow to collect any other feedback or
objections, and then push the 0001 patch
(recovery_init_sync_method=syncfs).

On Fri, Mar 19, 2021 at 4:08 PM Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
> 0002 patch looks good to me. Thanks!
> I have minor comments.

Ok, I made the changes you suggested. Let's see if anyone else would
like to vote for or against the concept of the 0002 patch
(recovery_init_sync_method=none).

Attachment Content-Type Size
v6-0001-Provide-recovery_init_sync_method-syncfs.patch text/x-patch 11.0 KB
v6-0002-Provide-recovery_init_sync_method-none.patch text/x-patch 4.3 KB
v6-0003-Provide-recovery_init_sync_method-wal.patch text/x-patch 16.7 KB

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