From: PG Bug reporting form <noreply@postgresql.org>
To: pgsql-bugs@lists.postgresql.org
Cc: emil@iggland.com
Subject: BUG #17141: SELECT LIMIT WITH TIES FOR UPDATE SKIP LOCKED returns wrong number of rows
Date: Wed, 11 Aug 2021 16:38:15 +0000
Message-ID: <17141-913d78b9675aac8e@postgresql.org> (raw)
The following bug has been logged on the website:
Bug reference: 17141
Logged by: Emil Iggland
Email address: emil@iggland.com
PostgreSQL version: 13.3
Operating system: Windows
Description:
I am trying to create a queue which should assign multiple tasks to a
worker. I use row locking with FOR UPDATE SKIP LOCKED, but the number of
rows returned are inconsistent with what I expect.
Minimum example:
CREATE TABLE queue (task INTEGER);
INSERT INTO queue (task)
VALUES (180),(280),(380),(480),(580),(180),(280),(380),(480),(580);
BEGIN;
SELECT * FROM queue
ORDER BY task DESC
FETCH FIRST 1 ROWS WITH TIES
FOR UPDATE SKIP LOCKED;
/* Some work to be done here */
COMMIT;
select version();
PostgreSQL 13.3, compiled by Visual C++ build 1914, 64-bit
Expected result Worker 1: (580), (580), Actual result Worker 1: (580),
(580)
Expected result Worker 2: (480), (480), Actual result Worker 2: (480)
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To: pgsql-bugs@postgresql.org
Cc: noreply@postgresql.org, pgsql-bugs@lists.postgresql.org, emil@iggland.com
Subject: Re: BUG #17141: SELECT LIMIT WITH TIES FOR UPDATE SKIP LOCKED returns wrong number of rows
In-Reply-To: <17141-913d78b9675aac8e@postgresql.org>
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