問64
頻出度★☆☆
データ処理に関する記述 a～c のうち, DBMS を導入することによって得られる効果だけを全て挙げたものはどれか。 a 同じデータに対して複数のプログラムから同時にアクセスしても, 一貫性が保たれる。 b 各トランザクションの優先度に応じて, 処理する順番を DBMS が決めるので, リアルタイム処理の応答時間が短くなる。 c 仮想記憶のページ管理の効率が良くなるので, データ量にかかわらずデータへのアクセス時間が一定になる。
令和2年度 ITパスポート試験 問64
テクノロジ系データベース › データベース方式
This question's explanation and your answers so far.
解説
問 64
- ア
正解 A representative effect obtained by introducing a DBMS is that even when multiple programs or users access the same data simultaneously, concurrency control (locking / exclusive control) keeps the data consistent and coherent. This corresponds to description a. Description b (shortening the real-time response time by deciding the processing order according to priority) and c (making the access time constant through more efficient virtual-memory page management) are both not genuine effects of a DBMS. Therefore, the only option that lists just a DBMS effect is a, and the correct answer is “ア”.
Incorrectイ
This lists “a, c”, but c is wrong. Virtual-memory page management is a memory-management function of the OS (operating system), not an effect of a DBMS, and there is also no guarantee that the access time stays constant regardless of the amount of data. The answer should include only a, which is the DBMS effect, so this is inappropriate.
Incorrectウ
This lists only “b”, but b is wrong. Deciding the processing order by transaction priority to shorten the real-time response time is not an effect generally guaranteed by a DBMS, nor can it be regarded as a representative effect of introducing a DBMS. It also fails to include the correct effect a, which makes it inappropriate as well.
Incorrectエ
This lists “b, c”, but neither b nor c is an effect of a DBMS. b concerns priority control of real-time processing, and c concerns the OS's virtual-memory management; both are inappropriate as effects of introducing a DBMS. It also fails to include the correct a, so it is wrong.
ここがポイント
- The main effects of a DBMS include maintaining data consistency and integrity through concurrency control (locking / exclusive control), centralized management and sharing of data, security protection (access control), and failure recovery (backup and recovery).
- Be sure to distinguish that virtual-memory page management and priority-based real-time processing belong to the domain of the OS or scheduling, and are not inherent effects of a DBMS.
用語