問61
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DBMS のトランザクションに関する記述として, 適切なものはどれか。
令和7年度 ITパスポート試験 問61
テクノロジ系データベース › トランザクション処理
This question's explanation and your answers so far.
解説
問 61
Incorrectア
Copying the contents of one database to another and keeping them synchronized describes “replication.” It is a function that maintains copies of data to improve availability or distribute load, and is distinct from a transaction, which commits or undoes processing; therefore it is incorrect.
Incorrectイ
Recording the operations performed on a database in sequence describes “acquiring a log (journal / update history).” Logs are used together with transactions as material for failure recovery and rollback, but the recording itself is not the definition of a transaction; therefore it is incorrect.
- ウ
正解 A transaction is a mechanism that treats multiple operations on a database as “a single indivisible unit (atomicity).” Its key feature is “all or nothing”: the changes are confirmed (committed) only when the entire series of operations succeeds, and if even one of them fails midway, all changes made so far are undone and the database is returned to its state before the processing began (rollback). This prevents a “half-applied, partially reflected” state and protects data consistency. Choice ウ faithfully describes exactly this behavior—“commit if everything succeeds, return to the pre-processing state if it fails midway”—so it is an appropriate description of a transaction.
Incorrectエ
Creating an index for a table and using it when searching describes an “index.” It is a mechanism for speeding up searches and is unrelated to a transaction, which handles committing or undoing processing; therefore it is incorrect.
ここがポイント
- Transaction = a mechanism that treats a series of operations on a database as a single indivisible unit (atomicity): commit (confirm) if all succeed, roll back (restore to the pre-processing state) if it fails midway.
- Distinguishing it from similar terms: replication (copying and synchronization), log / journal (recording operations), and index (speeding up searches with an index) are all functions distinct from a transaction itself.
用語