Re: fdatasync performance problem with large number of DB files

On 2021/03/19 10:37, Thomas Munro wrote:
> On Fri, Mar 19, 2021 at 2:16 PM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
>> PS: For illustration/discussion, I've also attached a "none" patch. I
>> also couldn't resist rebasing my "wal" mode patch, which I plan to
>> propose for PG15 because there is not enough time left for this
>> release.
>
> Erm... I attached the wrong version by mistake. Here's a better one.

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,

ereport(LOG,
(errcode_for_file_access(),
errmsg("could not open \"%s\": %m", path)))

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION