Locks placed by command are implicit locks.

More Questions from Managing Multiuser Databases

• The size of a lock is referred to as lock sizing.
• The goal of database security is to ensure that only authorized users can perform authorized activities at authorized times.
• Resource locking is a process to prevent multiple applications from obtaining copies of the same record when the record is about to be changed.
• In optimistic locking, the assumption is made that conflict will occur.
• When one transaction reads a changed record that has not been committed to the database a filthy read occurs.
• The transaction log contains a copy of every database record (or page) after it has changed. These records are called before images.
• The lost update problem is when User A reads data that have been processed by a portion of a transaction from User B.
• Locks placed by the DBMS are explicit locks.

Discussion & Comments