Re: Use pg_pwritev_with_retry() instead of write() in dir_open_for_write() to avoid partial writes?

On Sat, Aug 6, 2022 at 12:11 PM Michael Paquier <michael(at)paquier(dot)xyz> wrote:
>
> On Fri, Aug 05, 2022 at 03:55:26PM +0530, Bharath Rupireddy wrote:
> > I noticed that dir_open_for_write() in walmethods.c uses write() for
> > WAL file initialization (note that this code is used by pg_receivewal
> > and pg_basebackup) as opposed to core using pg_pwritev_with_retry() in
> > XLogFileInitInternal() to avoid partial writes. Do we need to fix
> > this?
>
> 0d56acfb has moved pg_pwritev_with_retry to be backend-only in fd.c :/

Yeah. pg_pwritev_with_retry can also be part of common/file_utils.c/.h
so that everyone can use it.

> > Thoughts?
>
> Makes sense to me for the WAL segment pre-padding initialization, as
> we still want to point to the beginning of the segment after we are
> done with the pre-padding, and the code has an extra lseek().

Thanks. I attached the v1 patch, please review it.

--
Bharath Rupireddy
RDS Open Source Databases: https://aws.amazon.com/rds/postgresql/