Oracle enqueues are locks at the database level that coordinate parallel access to Oracle resources such as objects or data records.
For example, enqueues are responsible for several transactions not being able to change the same data record at the same time. Enqueue requests are divided into queues whose requests are then processed in the chronological sequence of their arrival.
Possible Causes:
This wait event indicates a wait for a lock that is held by another session (or sessions) in an incompatible mode to the requested mode.
Generally due to table or application set up issues
This indicates contention for row-level lock. This wait occurs when a transaction tries to update or delete rows that are
currently locked by another transaction.
This usually is an application issue.
Generally due to application issues, particularly if foreign key constraints have not been indexed.
