Horton

Re: [PoC] pg_upgrade: allow to upgrade publisher node

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
Cc: Andres Freund <andres@anarazel.de>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, Dilip Kumar <dilipbalaut@gmail.com>, Peter Smith <smithpb2250@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Bruce Momjian <bruce@momjian.us>, Julien Rouhaud <rjuju123@gmail.com>, vignesh C <vignesh21@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: 2023-10-16T09:13:57Z
Lists: pgsql-hackers

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On Sat, Oct 14, 2023 at 10:45 AM Hayato Kuroda (Fujitsu)
<kuroda.hayato@fujitsu.com> wrote:
>
> Here is a new patch.
>
> Previously I wrote:
> > Based on above idea, I made new version patch which some functionalities were
> > exported from pg_resetwal. In this approach, pg_upgrade itself removed WALs and
> > then create logical slots, then pg_resetwal would be called with new option
> > --no-switch, which avoid to switch a WAL segment file. The option is only used
> > for the upgrading purpose so it is not written in doc and usage(). This option
> > is not required if pg_resetwal -o does not discard WAL records. Please see the
> > fork thread [1].
>
> But for now, these changes were reverted because changing pg_resetwal -o stuff
> may be a bit risky. This has been located more than ten years so that we should
> be more careful for modifying.
> Also, I cannot come up with problems if slots are created after the pg_resetwal.
> Background processes would not generate decodable changes (listed in [1]), and
> BGworkers by extensions could be ignored [2].
> Based on the discussion on forked thread [3] and if it is accepted, we will apply
> again.
>

Yeah, I think introducing additional complexity unless it is really
required sounds a bit scary to me as well. BTW, please find attached
some cosmetic changes.

One minor additional comment:
+# Initialize subscriber cluster
+my $subscriber = PostgreSQL::Test::Cluster->new('subscriber');
+$subscriber->init(allows_streaming => 'logical');

Why do we need to set wal_level as logical for subscribers?

-- 
With Regards,
Amit Kapila.

Commits

  1. Fix issues in binary_upgrade_logical_slot_has_caught_up().

  2. Fix a random failure in 003_logical_slots.pl.

  3. Fix a test in 003_logical_slots.

  4. Fix uninitialized slot array access during the upgrade.

  5. Fix the test 003_logical_slots.

  6. Commit b195e6d482 forgot to update meson.build.

  7. Use shorter file names in the upgrade logical slots test.

  8. Migrate logical slots to the new node during an upgrade.

  9. Flush logical slots to disk during a shutdown checkpoint if required.

  10. Prevent possibility of panics during shutdown checkpoint.