The lowest frequency allowed in the GUI for a DPA alert is once every 10 minutes. An alert may need to run more often. DPA alert information is stored in a table named CON_ALERT and this table can be updated to change the frequency
select id, alertname, frequency from con_alert order by alertname;
update con_alert set frequency = <number_of_minutes> where id = '<id_of_alert>';</id_of_alert></number_of_minutes>
If you update the alert in the Ignite GUI, the frequency may be set back to 10 minutes. If this happens, you must update the alert again following the steps above.