Re: Misunderstanding transactions and locks - Mailing list pgsql-general

From Alvaro Herrera
Subject Re: Misunderstanding transactions and locks
Date
Msg-id 1276718397-sup-9623@alvh.no-ip.org
Whole thread Raw
In response to Misunderstanding transactions and locks  ("Michael P. Soulier" <michael_soulier@mitel.com>)
Responses Re: Misunderstanding transactions and locks  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
Excerpts from Michael P. Soulier's message of mié jun 16 12:21:16 -0400 2010:
> Hi,
>
> I'm using Django with Postgres 8.3.9 on CentOS Linux.
>
> I'm trying to figure out why locking isn't working as I'm expecting. I have a
> an operation wrapped in a transaction where I explicitely grab an exclusive
> lock on my table. When another process concurrently runs to do the same, it
> should block on attempting to acquire the exclusive lock, no?

> 2010-06-16 12:14:31.913008500 LOG:  statement: LOCK TABLE instances IN ROW
> EXCLUSIVE MODE

"row exclusive mode" does not block itself.

--
Álvaro Herrera <alvherre@commandprompt.com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

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