IBM DB2 11.1 Advanced DBA for Linux, UNIX, and Windows — Question 30

Which of the following statements regarding locking is TRUE?

Answer options

• A. The same lock modes apply to tables, rows, or blocks
• B. Lock conversion can take place implicitly as a query executes
• C. Changing the mode of a lock that is already held is called lock escalation
• D. Lock conversion is not necessary if an X lock is required and an S or U lock is currently held

Correct answer: B

Explanation

The correct answer is B because lock conversion can happen implicitly while a query is running, allowing for more flexible locking behavior. Option A is incorrect as lock modes can vary between tables, rows, and blocks. Option C misdefines lock escalation, which specifically refers to upgrading a lock's mode rather than changing it. Option D is wrong because lock conversion may still be necessary even when an S or U lock is present before obtaining an X lock.