Exam 15: Transaction Management

A(n)______________________ is a collection of operations that must be processed reliably as a single unit of work.

For each transaction,the ____________________ statement can be used to specify whether deferrable constraints are deferred or immediately enforced.

Julia has a lock on the savings account and Bill is trying to perform a conflicting action on the data:

When an update to the database takes place,the time of the update,the values of the data before and after the update,and the type of lock used are recorded in the transaction log.

The optimistic concurrency control approach may delay a transaction longer than the pessimistic approach would have,because with the optimistic approach the conflicting transactions have to be rolled back and restarted,rather than waiting for a lock to be released.

A(n)____________________ is an inconsistent retrieval problem which occurs when a transaction reads several values,but another transaction updates some of the values while the first transaction is still executing.

Julia has a shared lock on the savings account and Bill is trying to perform an action requesting an exclusive lock on the same data:

Which of the following will cause a deadlock?

Some transactions have tentative actions that can be canceled by user actions or other events.In order to allow a partial rollback of a transaction (to save parts of the transaction not affected by those user actions or events),SQL:2003 provides the _______ statement.

Which of the following is an example of lost update?

Consider a transaction that updates each of the 100 employees' salaries in a table (there is one row per employee)under the immediate update mode.The transaction terminates abnormally after 10 rows have been updated in the database (and the normal operations have taken place on the log).What should the recovery procedure perform to make sure the transaction completes as desired?

Depending on the DBMS,checkpoints:

Any number of users can hold a shared lock on the same part of the database,but only one user can hold an exclusive lock on that part of the database.

With database locking,a(n)_______________ lock must be obtained before reading a database item,and a(n)___________ lock must be obtained before writing to a database item.

The ACID properties are insured by the following services of the DBMS:

Checkpoints can involve considerable disruption to transaction processing because no new transactions can begin and existing transactions cannot begin new operations during a checkpoint.

In the optimistic approach:

Julia has an exclusive lock on the savings account and Bill is trying to perform an action requesting a shared lock on the same data:

An example of concurrency transparency would be that multiple students could register for the same course offering at the same time,without interference from each other.

Three enabling technologies which support workflow are distributed object management,recovery management,and customized transaction management.