Horton

Re: [Patch] pg_rewind: options to use restore_command from recovery.conf or command line

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Alexey Kondratov <a.kondratov@postgrespro.ru>
Cc: Alexander Korotkov <a.korotkov@postgrespro.ru>, Alvaro Herrera <alvherre@2ndquadrant.com>, Liudmila Mantrova <l.mantrova@postgrespro.ru>, Thomas Munro <thomas.munro@gmail.com>, Andrey Borodin <x4mmm@yandex-team.ru>, David Steele <david@pgmasters.net>, Andres Freund <andres@anarazel.de>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Dmitry Dolgov <9erthalion6@gmail.com>, vladimirlesk@yandex-team.ru, dsarafan@yandex-team.ru
Date: 2020-03-06T01:21:20Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Move frontend-side archive APIs from src/common/ to src/fe_utils/

  2. Add -c/--restore-target-wal to pg_rewind

  3. Move routine definitions of xlogarchive.c to a new header file

  4. Move routine building restore_command to src/common/

  5. Integrate recovery.conf into postgresql.conf

On Thu, Mar 05, 2020 at 07:52:24PM +0300, Alexey Kondratov wrote:
> OK, I was still having in mind pg_rewind as the only one user of this
> routine. Now it is a part of the common and I could imagine a hypothetical
> tool that is polling the archive and waiting for a specific WAL segment to
> become available. In this case 'command not found' is definitely the end of
> game, while the absence of segment is expected error, so we can continue
> looping.

Depending on the needs, we could also add in the future an option in
this API to not exit if the command is missing.  Who knows if a case
can be made..

By the way, as a matter of transparency, I have discussed this patch
with Alexander offlist and he has pinged me that I may be in a better
place to commit it per the amount of review I have done, so I'll try
to handle it.  I was also thinking to split the patch into two pieces:
- Introduction of common/archive.c and common/fe_archive.c (the former
is used by xlogarchive.c and the latter only by pg_rewind).  The
latter is dead code without the second patch, but this would validate
the MSVC build with the buildfarm.
- The pg_rewind pieces with the new option.
--
Michael