Horton

Re: [PATCH] Clarify the behavior of the system when approaching XID wraparound

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: John Naylor <john.naylor@enterprisedb.com>
Cc: Aleksander Alekseev <aleksander@timescale.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Pavel Borisov <pashkin.elfe@gmail.com>
Date: 2023-09-20T03:41:07Z
Lists: pgsql-hackers 
On Sun, May 14, 2023 at 6:06 PM Peter Geoghegan <pg@bowt.ie> wrote:
> BTW, Google cloud already just instruct their users to ignore the
> xidStopLimit HINT about single user mode:
>
> https://cloud.google.com/sql/docs/postgres/txid-wraparound

I read this just today, and was reminded of this thread:

https://cloud.google.com/blog/products/databases/alloydb-for-postgresql-under-the-hood-adaptive-autovacuum

It reads:

"1. Transaction ID wraparound: PostgreSQL transaction IDs or XIDs are
32-bit unsigned integers that are assigned to each transaction and
also get incremented. When they reach their maximum value, it would
wrap around to zero (similar to a ring buffer) and can lead to data
corruption."

-- 
Peter Geoghegan

Commits

  1. Reword messages about impending (M)XID exhaustion.

  2. Talk about assigning, rather than generating, new MultiXactIds.

  3. Update the documentation on recovering from (M)XID exhaustion.