Horton

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

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: bharath.rupireddyforpostgres@gmail.com, michael@paquier.xyz, alvherre@alvh.no-ip.org, nathandbossart@gmail.com, thomas.munro@gmail.com, pgsql-hackers@lists.postgresql.org
Date: 2023-02-15T02:00:28Z
Lists: pgsql-hackers 
Hi

On 2023-02-15 10:28:37 +0900, Kyotaro Horiguchi wrote:
> At Tue, 14 Feb 2023 16:55:25 -0800, Andres Freund <andres@anarazel.de> wrote in 
> > Hi,
> > 
> > On 2023-02-14 18:00:00 +0530, Bharath Rupireddy wrote:
> > > Done, PSA v2 patch.
> > 
> > This feels way too complicated to me.  How about something more like the
> > attached?
> 
> I like this one, but the parameters offset and size are in a different
> order from pwrite(fd, buf, count, offset).  I perfer the arrangement
> suggested by Bharath.

Yes, it probably is better. Not sure why I went with that order.


> And isn't it better to use Min(remaining_size, BLCKSZ) instead of a bare if
> statement?

I really can't make myself care about which version is better :)

Greetings,

Andres Freund

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.