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.munro@gmail.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