平成30年度秋期 ITパスポート試験問63

This question's explanation and your answers so far.

問63

頻出度★☆☆

トランザクション処理におけるロールバックの説明として, 適切なものはどれか。

出典　平成30年度秋期 ITパスポート試験問63

解説

問 63

Incorrectア
When a transaction is updating shared data, prohibiting other transactions from updating that data is the description of a lock (exclusive control). It is a mechanism to prevent data inconsistency during concurrent execution, and it is a different function from rollback, which rolls back after a failure.
Incorrectイ
Finalizing the updates when a transaction is processed normally is the description of commit. Rollback is the process of undoing updates when the transaction does not complete normally, which is the exact opposite operation to commit.
ウ
正解 Rollback is the process of undoing all updates made by a transaction and restoring the database to the state it was in before the transaction started, when the transaction cannot complete normally for some reason (an error during processing, a deadlock, a failure, etc.). This preserves data consistency (atomicity). Because this operation recovers by tracing back into the past, it is also called backward recovery. Choice ウ matches this description, so ウ is the correct answer.
Incorrectエ
Combining multiple tables into a single table using the columns that relate them to each other as keys is the description of the join operation in a relational database, and it has nothing to do with rollback, which is a transaction recovery process.

ここがポイント

Rollback = the process of undoing updates and restoring the database to its state before the start when a transaction does not end normally (backward recovery).
Do not confuse it with its counterpart commit (finalizing updates), lock (exclusive control), or join.

用語

解答問63ウ