BUG #7924: Trigger update function don't take correct values

[m***@cir.es]

The following bug has been logged on the website:

Bug reference: 7924
Logged by: Maria
Email address: ***@cir.es
PostgreSQL version: Unsupported/Unknown
Operating system: RedHat
Description:

Hi!

I have a trigger that when you update a value on a table, makes an insert
into another table.

The trigger looks like the following:

BEGIN
set datestyle to 'sql';
set datestyle to 'european';
IF (TG_OP = 'UPDATE' and (OLD.situation!=NEW.situation)) THEN
INSERT INTO table_B VALUES (OLD.id,NEW.situation,NOW());
END IF;
RETURN NULL;
END;

For exemple, If I do the next querys:
--> update table_A set situation='Started' where id='23';
On table_A appears:
id | situation
--------+-----------
23 | Started

On table_B appears:
id | situation | when
--------+-----------+---------------------
23 | Started | 2013-03-08 12:33:35


--> update table_A set situation='Waiting' where id='23';
On table_A appears:
id | situation
--------+-----------
23 | Waiting

On table_B appears:
id | situation | when
--------+-----------+---------------------
23 | Started | 2013-03-08 12:33:35
23 | Started | 2013-03-08 12:33:37

I don't understand why after the second update, the insert done on table_B
is incorrect, and has the same values that the first one.

I've been looking for some kind of explanation like cache or something, but
I couldn't find anything.

Thanks in advance.

Maria

[Kevin Grittner]

   id    | situation | when
--------+-----------+---------------------
   23    | Started  | 2013-03-08 12:33:35
   23    | Started  | 2013-03-08 12:33:37
I don't understand why after the second update, the insert done on table_B
is incorrect, and has the same values that the first one.
I've been looking for some kind of explanation like cache or something, but
I couldn't find anything.

It helps to provide a self-containted test case like this:

test=# CREATE TABLE table_a (id int PRIMARY KEY, situation text NOT NULL);
CREATE TABLE
test=# INSERT INTO table_a VALUES (23, 'Unknown');
INSERT 0 1
test=# CREATE TABLE table_b (id int NOT NULL, sitation text NOT NULL, "when" timestamptz NOT NULL);
CREATE TABLE
test=# CREATE FUNCTION log_func()
test-#   RETURNS TRIGGER
test-#   LANGUAGE plpgsql
test-# AS $$
test$# BEGIN
test$#   set datestyle to 'sql';
test$#   set datestyle to 'european';
test$#   IF (TG_OP = 'UPDATE' and (OLD.situation!=NEW.situation)) THEN
test$#     INSERT INTO table_B VALUES (OLD.id,NEW.situation,NOW());
test$#   END IF;
test$#   RETURN NULL;
test$# END;
test$# $$;
CREATE FUNCTION
test=# CREATE TRIGGER log_trig
test-#   AFTER UPDATE ON table_a
test-#   FOR EACH ROW EXECUTE PROCEDURE log_func();
CREATE TRIGGER
test=# update table_A set situation='Started' where id='23';
UPDATE 1
test=# select * from table_a;
 id | situation
----+-----------
 23 | Started
(1 row)

test=# select * from table_b;
 id | sitation |              when             
----+----------+--------------------------------
 23 | Started  | 08/03/2013 13:01:08.169213 CST
(1 row)

test=# update table_A set situation='Waiting' where id='23';
UPDATE 1
test=# select * from table_a;
 id | situation
----+-----------
 23 | Waiting
(1 row)

test=# select * from table_b;
 id | sitation |              when             
----+----------+--------------------------------
 23 | Started  | 08/03/2013 13:01:08.169213 CST
 23 | Waiting  | 08/03/2013 13:01:08.179754 CST
(2 rows)

How about showing us yours?

--
Kevin Grittner
EnterpriseDB: http://www.enterprisedb.com
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