Horton

RE: Slow catchup of 2PC (twophase) transactions on replica in LR

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

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From: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
To: 'Давыдов Виталий' <v.davydov@postgrespro.ru>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Ajin Cherian <itsajin@gmail.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Date: 2024-04-22T08:54:48Z
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. Fix random failure in 021_twophase.

  2. Allow altering of two_phase option of a SUBSCRIPTION.

  3. Doc: use true|false rather than on|off for "failover" option

  4. Support an optional asynchronous commit mode, in which we don't flush WAL

Dear Vitaly,

> I looked at the patch and realized that I can't try it easily in the near future
> because the solution I'm working on is based on PG16 or earlier. This patch is
> not easily applicable to the older releases. I have to port my solution to the
> master, which is not done yet.

We also tried to port our patch for PG16, but the largest barrier was that a
replication command ALTER_SLOT is not supported. Since the slot option two_phase
can't be modified, it is difficult to skip decoding PREPARE command even when
altering the option from true to false.
IIUC, Adding a new feature (e.g., replication command) for minor updates is generally
prohibited

We must consider another approach for backpatching, but we do not have solutions
for now.

Best Regards,
Hayato Kuroda
FUJITSU LIMITED
https://www.fujitsu.com/global/