Horton

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

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>

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From: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
To: 'Amit Kapila' <amit.kapila16@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Julien Rouhaud <rjuju123@gmail.com>, vignesh C <vignesh21@gmail.com>
Date: 2023-08-04T12:54:51Z
Lists: pgsql-hackers 
Dear Amit,

> So, we have three options here (a) As you have done in the patch,
> document this limitation and request user to perform some manual steps
> to drop the subscription; (b) don't allow upgrade to proceed if there
> are invalid slots in the old cluster; (c) provide a new function like
> pg_copy_logical_replication_slot_contents() where we copy the required
> contents like invalid status(ReplicationSlotInvalidationCause), etc.
> 
> Personally, I would prefer (b) because it will minimize the steps
> required to perform by the user after the upgrade and looks cleaner
> solution.
> 
> Thoughts?

Thanks for suggestion. I agreed (b) was better because it did not endanger users
for data lost. I implemented locally and worked well, so I'm planning to adopt
the idea in next version, if no objections.

Best Regards,
Hayato Kuroda
FUJITSU LIMITED

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.