Killing idle sessions

In PostgreSQL, a session or a transaction can basically live almost forever. In some cases, this has been a problem because transactions were kept open for too long. Usually, this was due to a bug. The trouble is this: insanely long transactions can cause cleanup problems and table bloat can occur. The uncontrolled growth of a table (table bloat) naturally leads to performance problems and unhappy end users.

Starting with PostgreSQL 9.6, it is possible to limit the duration a database connection is allowed to spend inside a transaction without performing real work. Here is how it works:

test=# SET idle_in_transaction_session_timeout TO 2500; 
SET 
test=# BEGIN; 
BEGIN 
test=# SELECT 1; 
 ?column?  
---------- 
        1 
(1 row) 

test=# SELECT 1; 
FATAL:  terminating connection due to idle-in-transaction timeout 

Administrators and developers can set a timeout, which is 2.5 seconds in my example. As soon as a transaction is idle for too long, the connection will be terminated automatically by the server. Nasty side effects of long idle transactions can be prevented easily by adjusting this parameter.