Horton

Re: Attempt to consolidate reading of XLOG page

Haribabu Kommi <kommi.haribabu@gmail.com>

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From: Haribabu Kommi <kommi.haribabu@gmail.com>
To: Antonin Houska <ah@cybertec.at>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2019-04-12T08:48:33Z
Lists: pgsql-hackers 
On Fri, Apr 12, 2019 at 2:06 AM Antonin Houska <ah@cybertec.at> wrote:

> While working on the instance encryption I found it annoying to apply
> decyption of XLOG page to three different functions. Attached is a patch
> that
> tries to merge them all into one function, XLogRead(). The existing
> implementations differ in the way new segment is opened. So I added a
> pointer
> to callback function as a new argument. This callback handles the specific
> ways to determine segment file name and to open the file.
>
> I can split the patch into multiple diffs to make detailed review easier,
> but
> first I'd like to hear if anything is seriously wrong about this
> design. Thanks.
>

I didn't check the code, but it is good to combine all the 3 page read
functions
into one instead of spreading the logic.

Regards,
Haribabu Kommi
Fujitsu Australia

Commits

  1. Remove logical_read_local_xlog_page

  2. Refactor WAL file-reading code into WALRead()

  3. Rework WAL-reading supporting structs

  4. Make XLogReaderInvalReadState static

  5. Use pg_pread() and pg_pwrite() for data files and WAL.