Locking is a mechanism to ensure data integrity while allowing maximum concurrent access to data. It is used to implement concurrency control when multiple users access table to manipulate its data at the same time.
The two basic types of locks are DML (table) locks, and DDL (dictionary) locks.
DML locks are designed to guarantee data integrity in a multi-user environment. DML locks prevent conflicting DML and DDL operations from interfering with each other’s operations. These locks are generally either table level locks, or row level locks.
Following are different lock types:
1. Table Level Lock
2. Row Level Lock
3. DML Locks in Transactions Enqueue Mechanism
4. DML Locks in Blocks Automatic Table Lock Modes
5. Manual Table Lock Modes
6. Table Partition Locks
