in fact we use a simple "select 1 from dual", this causes few load, but the problem is that our dba's see millions of hits on the db, this generate some load that we wants to limit (by executing this query only every x time for exemple)... i see in the doc: check-valid-connection-sql : This is a SQL statement that should be run on a connection before it is returned from the pool to test its validity to test for stale pool connections. An example statement could be: select count(*) from x maybe i don't understand exactly when the querry will be executed, but i suppose it is for every connection to the db... what i would like to have is to use the check-valid-connection not for every connection, but one every 10 seconds, for exemple, that will validate that the db is still reachable and all connection are considered as ok... don't know if it makes sense? View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4212983#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...