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Re: table_open/table_close with different lock mode

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Junwang Zhao <zhjwpku@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-07-21T06:26:22Z
Lists: pgsql-hackers 
On Fri, Jul 21, 2023 at 02:05:56PM +0800, Junwang Zhao wrote:
> I noticed there are some places calling table_open with
> RowExclusiveLock but table_close with NoLock, like in function
> toast_save_datum.
> 
> Can anybody explain the underlying logic, thanks in advance.

This rings a bell.  This is a wanted behavior, see commit f99870d and
its related thread:
https://postgr.es/m/17268-d2fb426e0895abd4@postgresql.org

The tests added by this commit in src/test/isolation/ will show the
difference in terms of the way the toast values get handled with and
without the change.
--
Michael

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 corruption of toast indexes with REINDEX CONCURRENTLY