Re: [PATCH] doc: clarify pg_stat_lock.fastpath_exceeded scope

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Tatsuya Kawata <kawatatatsuya0913@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Postgres hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-06-22T05:05:20Z
Lists: pgsql-hackers
Hi Kawata-san,

On Sat, Jun 20, 2026 at 06:14:59PM +0900, Tatsuya Kawata wrote:
> Hi Bertrand-san, Michael-san,
> 
> Thanks for the feedback.  Centralizing the explanation and linking
> from views makes sense, so v2 takes that approach.

Thanks for the new version.

--- a/doc/src/sgml/mvcc.sgml
+++ b/doc/src/sgml/mvcc.sgml
@@ -1248,6 +1248,35 @@ ERROR:  could not serialize access due to read/write dependencies among transact
       </tbody>
      </tgroup>
     </table>
+
+    <sect3 id="locking-tables-fast-path">
+     <title>Fast-Path Locking</title>

The location looks ok to me.

+      for eligible locks, fast-path is used only when a per-backend slot is
+      available;

Should we add a description of the consequences of not being able to acquire the
lock in fast-path (when there are no available slots)? For example, we could
say that this is considerably more expensive and may be subject to contention.

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com



Commits

  1. doc: Add new section describing fast-path locking