Re: fdatasync performance problem with large number of DB files

On 2021/03/15 8:33, Thomas Munro wrote:
> On Mon, Mar 15, 2021 at 11:52 AM Thomas Munro <thomas.munro@gmail.com> wrote:
>> Time being of the essence, here is the patch I posted last year, this
>> time with a GUC and some docs.  You can set sync_after_crash to
>> "fsync" (default) or "syncfs" if you have it.
> 
> Cfbot told me to add HAVE_SYNCFS to Solution.pm, and I fixed a couple of typos.

Thanks for the patch!

+        When set to <literal>fsync</literal>, which is the default,
+        <productname>PostgreSQL</productname> will recursively open and fsync
+        all files in the data directory before crash recovery begins.

Isn't this a bit misleading? This may cause users to misunderstand that
such fsync can happen only in the case of crash recovery.

Regards,

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