I was found a bug in PostgreSQL 8.0.0beta3.
It isn't in PostgreSQL 7.4.5.
$ createdb test
$ psql test
test=# SELECT version ();
version
-----------------------------------------------------------------------------
PostgreSQL 8.0.0beta3 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 3.3.4
(1 row)
test=# LISTEN a;
test=# LISTEN b;
test=# SELECT * FROM pg_listener l WHERE NOT EXISTS (select 1 from pg_stat_activity a
where a.procpid=l.listenerpid);
relname | listenerpid | notification
---------+-------------+--------------
b | 2020 | 0
(1 row)
test=# LISTEN c;
test=# LISTEN d;
test=# LISTEN e;
test=# LISTEN f;
test=# SELECT * FROM pg_listener l WHERE NOT EXISTS (select 1 from pg_stat_activity a
where a.procpid=l.listenerpid);
relname | listenerpid | notification
---------+-------------+--------------
b | 2020 | 0
d | 2020 | 0
f | 2020 | 0
(3 rows)
test=# SELECT * INTO temp_listener FROM pg_listener;
SELECT
test=# SELECT * FROM temp_listener l WHERE NOT EXISTS (select 1 from pg_stat_activity
a where a.procpid=l.listenerpid);
relname | listenerpid | notification
---------+-------------+--------------
b | 2020 | 0
d | 2020 | 0
f | 2020 | 0
(3 rows)
(not a pg_listener bug)
test=# SELECT * INTO temp_stat_activity FROM pg_stat_activity;
SELECT
test=# SELECT * FROM temp_listener l WHERE NOT EXISTS (select 1 from
temp_stat_activity a where a.procpid=l.listenerpid);
relname | listenerpid | notification
---------+-------------+--------------
(0 rows)
(not an EXISTS bug)
Note: If backend terminated abnormally or server powered down, the
pg_listener's records cannot be deleted.
I using a script at times:
DELETE FROM pg_listener WHERE NOT EXISTS (select 1 from pg_stat_activity a where
a.procpid=pg_listener.listenerpid);
In PostgreSQL 7.4.5 it's working fine.
"TODO: Allow LISTEN/NOTIFY to store info in memory rather than tables" is
good idea. How soon may i expect this feature? :)
-Sygma
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