From: andreigorita@gmail.com
To: pgsql-bugs@postgresql.org
Cc: andreigorita@gmail.com
Subject: BUG #14870: wrong query results when using WITH with UPDATE
Date: Tue, 24 Oct 2017 15:53:58 +0000
Message-ID: <20171024155358.1471.82377@wrigleys.postgresql.org> (raw)
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The following bug has been logged on the website:
Bug reference: 14870
Logged by: Andrei Gorita
Email address: andreigorita@gmail.com
PostgreSQL version: 9.6.1
Operating system: CentOS
Description:
when updating a table with unique index within a WITH part of a query, in
certain conditions the query reports that updated more than one row.
A simple way to reproduce:
test=> create table tmp_test(id int not null, test text not null);
CREATE TABLE
test=> create unique index on tmp_test(id);
CREATE INDEX
test=> INSERT INTO tmp_test VALUES (1, 'test');
INSERT 0 1
test=> create table tmp_test2(id int not null, test text not null);
CREATE TABLE
test=> WITH updated AS (UPDATE tmp_test SET test = 'test' WHERE id = 1
RETURNING id), inserted AS (INSERT INTO tmp_test2 (id, test) SELECT 1,
'test' WHERE NOT EXISTS (SELECT 1 FROM updated) RETURNING id) SELECT * FROM
updated;
id
----
1
(1 row)
This is the expected result, but when another session is executing in
parallel:
test=> begin;
BEGIN
test=> UPDATE tmp_test SET test = 'test' WHERE id = 1;
UPDATE 1
test=> commit;
COMMIT
the result is:
test=> WITH updated AS (UPDATE tmp_test SET test = 'test' WHERE id = 1
RETURNING id), inserted AS (INSERT INTO tmp_test2 (id, test) SELECT 1,
'test' WHERE NOT EXISTS (SELECT 1 FROM updated) RETURNING id) SELECT * FROM
updated;
id
----
1
1
(2 rows)
which is at least strange.
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To: pgsql-bugs@postgresql.org
Cc: andreigorita@gmail.com
Subject: Re: BUG #14870: wrong query results when using WITH with UPDATE
In-Reply-To: <20171024155358.1471.82377@wrigleys.postgresql.org>
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