In Oracle, a deadlock occurs when two or more sessions are waiting for each other to release a lock. This can happen when two sessions are trying to update the same row in a table, or when one session is trying to update a row that is locked by another session.
There are a few ways to check for deadlocks in Oracle. One way is to use the v$lock
view. This view shows all of the locks that are currently being held in the database. If you see two or more sessions that are waiting for each other to release a lock, then you have a deadlock.