How to check Oracle database for long running queries

Question

My application, which uses an Oracle database, is going slow or appears to have stopped completely.

How can find out which queries are most expensive, so I can inves

Answer 1

You can use the v$sql_monitor view to find queries that are running longer than 5 seconds. This may only be available in Enterprise versions of Oracle. For example this query will identify slow running queries from my TEST_APP service:

select to_char(sql_exec_start, 'dd-Mon hh24:mi'), (elapsed_time / 1000000) run_time,
       cpu_time, sql_id, sql_text 
from   v$sql_monitor
where  service_name = 'TEST_APP'
order  by 1 desc;

Note elapsed_time is in microseconds so / 1000000 to get something more readable