Exam 10: Transaction Management and Concurrency Control

means that data used during the execution of a transaction cannot be used by a second transaction until the first one is completed.

The scheduler's main job is to create a(n) of a transaction's operation, in which the interleaved executions of transactions yield the same results as if the transactions were executed in serial order.

A(n) specifically reserves access to the transaction that locked the object.

All transactions must display .

An optimistic approach is based on the assumption that the majority of the database operations do not conflict.

The transaction recovery write-ahead-log protocol ensures that transaction logs are always written before any database data are actually updated.

The information stored in the is used by the DBMS for a recovery requirement triggered by a ROLLBACK statement, a program's abnormal termination, or a system failure such as a network discrepancy or a disk crash.

A(n) lock has only two stages (0 and 1).

Explain the transaction log. What is its function?

The DBMS guarantees that the semantic meaning of a transaction truly represents the real-world event.

Durability requires that all portions of the transaction must be treated as a single, logical unit of work in which all operations are applied and completed to produce a consistent database.

Serializability means that data used during the execution of a transaction cannot be used by a second transaction until the first one is completed.

The scheduler establishes the order in which the operations within concurrent transactions are executed.

In a page-level lock, the DBMS will lock an entire diskpage.

The ANSI has defined standards that govern SQL database transactions. Transaction support is provided by two SQL statements: and ROLLBACK.

A lock prevents the use of any tables in the database from one transaction while another transaction is being processed.

ensure that a disk physical failure will not impair the DBMS's ability to recover data.

What is transaction isolation and why it is important?

A transaction is a unit of work that must be either entirely completed or aborted.

Although the DBMS is designed to recover a database to a previous consistent state when an interruption prevents the completion of a required set of transactions, the transactions themselves are defined by the end user or programmer and must be correct.