Oracle 9i Lock

Why the lock concept is introduced
What is a lock
The management and allocation of all Oracle 9i locks is done automatically by the database management system, which does not require user intervention, but also provides manual locking commands for experienced users.
Classification of Locks
1. Divide by permissions
Exclusive lock
Shared locks
2. Division of resources by lock allocation
Data lock
Dictionary lock
Query Lock Information
(1) The database lock interface as shown in Figure 6.71.

(2) in the "Filter" Drop-down list box shown in the figure, you can choose the type of display lock, including 3 types, default to user type lock.
Table 6.6 Key information for locks

Name	Meaning
User name	Oracle UserID associated with a session that occupies or acquires a lock
Session ID	session that occupies or acquires a lock
Lock type	The type of user lock or system lock. User application Gets the user type lock. Any process that blocks other users may occupy one of these locks. User type locks include 3 kinds. TM (DML team), TX (transaction queue) and UL (User provided)
Manner of occupancy	How locks are locked by the session
Way to request	How the process requests locks to be locked
Object Name	Lock the name of an object
Limit of ROWID	Locked Current ROWID
Object owner	User name of object owner
Object type	Object type
Resource ID1	Lock identifier #1 (depending on type)
Resource ID2	Lock identifier #2 (depending on type)