Horton

Re: pg_preadv() and pg_pwritev()

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Sergey Shinderuk <s.shinderuk@postgrespro.ru>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2021-01-13T22:22:07Z
Lists: pgsql-hackers 
On Thu, Jan 14, 2021 at 9:26 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> * You need to remove pread.o and pwrite.o from the hard-wired
> part of the list in src/port/Makefile, else they get built
> whether needed or not.

Right, done.

> * I don't much like this in fd.h:
>
> @@ -46,6 +46,7 @@
>  #include <dirent.h>
>
>
> +struct iovec;
>  typedef int File;
>
> because it makes it look like iovec and File are of similar
> status, which they hardly are.  Perhaps more like
>
>  #include <dirent.h>
> +
> +struct iovec;                  /* avoid including sys/uio.h here */

Done, except I wrote port/pg_iovec.h.

> I confirm clean builds on Big Sur and Catalina with this.

Thanks for checking.  I also checked on Windows via CI.  Pushed.

Commits

  1. Improve our heuristic for selecting PG_SYSROOT on macOS.

  2. Move our p{read,write}v replacements into their own files.

  3. Don't use elog() in src/port/pwrite.c.

  4. Use vectored I/O to fill new WAL segments.

  5. Provide pg_preadv() and pg_pwritev().