I am getting ORA-02049 occasionally for some long-running and/or intensive transactions. There is seemingly no pattern to this, but it happens on a simple INSERT.
I have no clue how to get any sort of information out or Oracle, but there has to be a way? A log over locking or atleast a way to see current locks?
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Answer
One possible way might be to increase the INIT.ORA parameter for distributed_lock_timeout to a larger value. This would then give you a longer time to observe the v$lock table as the locks would last for longer.
To achieve automation of this, you can either
-
Run an SQL job every 5-10 seconds that logs the values of
v$lockor the query that sandos has given above into a table and then analyze it to see which session was causing the lock. -
Run a
STATSPACKor anAWRReport. The sessions that got locked should show up with high elapsed time and hence can be identified.
v$session has 3 more columns blocking_instance, blocking_session, blocking_session_status that can be added to the query above to give a picture of what is getting locked.