test1

The validation (optimistic) concurrency control protocol allows exactly all those schedules that are serializable to execute successfully:

• True

• False

The problem that may occur when one transaction T reads an item X that was written by another transaction T' before transaction T' commits is known as:

• The dirty read problem

• The phantom record problem

• The unrepeatable read problem

• The incorrect summary problem

• The lost update problem

In the multiple granularity concurrency control protocol, a parent item cannot be unlocked by a transaction until any child items locked by the same transaction are unlocked first:

• True

• False

The type of schedule that ensures the simplest recovery techniques is a:

• Recoverable schedule

• Strict schedule

• Cascadeless schedule

• Non-recoverable schedule

The problem that may occur when two transactions read the same database item before either one updates it, then one update overwrites the other is known as:

• The lost update problem

• The dirty read problem

• The incorrect summary problem

• The phantom record problem

• The unrepeatable read problem

What is the main advantage of the primary copy distributed concurrency control algorithm?

• Improved reliability/availability

• Fully distributed

• Simple extension to centralized concurrency control

• Provides good load balancing

Which relational algebra operation is used to specify horizontal partitioning?

• PROJECT

• SELECT

• RENAME

• UNION

• NATURAL JOIN

Which of the following protocols does not unlock any items that it has read-locked until the transaction ends:

• Basic 2PL

• Conservative 2PL

• Rigorous 2PL

• Strict 2PL

The type of schedule where a transaction T cannot read an item X until transactions T' has committed, where T' is the last transaction to write the item X, is a:

• Cascadeless schedule

• Recoverable schedule

• Non-recoverable schedule

• Strict schedule

The type of schedule that ensures the simplest recovery techniques is a:

• Cascadeless schedule

• b) Strict schedule

• c) Recoverable schedule

• d) Non-recoverable schedule