Horton

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

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Andres Freund <andres@anarazel.de>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Nathan Bossart <nathandbossart@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-02-14T07:06:24Z
Lists: pgsql-hackers 
On Mon, Feb 13, 2023 at 05:10:56PM -0800, Andres Freund wrote:
> I just tried to use pg_pwrite_zeros - and couldn't because it doesn't have an
> offset parameter.  Huh, what lead to the function being so constrained?

Its current set of uses cases, where we only use it now to initialize
with zeros with WAL segments.  If you have a case that plans to use
that stuff with an offset, no problem with me. 
--
Michael

Commits

  1. Revise pg_pwrite_zeros()

  2. Use pg_pwrite_zeros() in walmethods.c

  3. Introduce pg_pwrite_zeros() in fileutils.c

  4. Move pg_pwritev_with_retry() to src/common/file_utils.c

  5. Restore pg_pread and friends.

  6. Remove dead pread and pwrite replacement code.