問58
頻出度★☆☆
オンライントランザクション処理システムを構成するサーバ上のソフトウェアのうち，データベース管理システムの役割の説明として，適切なものはどれか。
平成21年度 春期 ITパスポート試験 問58
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 58
- ア
正解 The correct answer is ア. A database management system (DBMS) is dedicated software that manages the database in a unified way and actually reads and writes the data. In an online transaction processing (OLTP) system, business application programs do not manipulate the data files themselves. Instead, they send the DBMS requests such as “retrieve the data that meets this condition” or “update this value”, and the DBMS accepts those requests, retrieves or updates the data inside the database, and returns the result. Choice ア states exactly this original role of the DBMS: accepting requests from application programs and retrieving or updating the data in the database. The key point is that, because the DBMS makes itself the single point of entry for data operations, it can take on data management as a whole — concurrency control for simultaneous access, keeping data consistent, and recovery from failures.
Incorrectイ
This is the role of a transaction monitor (TP monitor). It is control software that accepts transaction processing requests arriving from clients, starts and dispatches the business application program that corresponds to each request, and handles large numbers of requests efficiently. What it deals with are clients and application programs; it does not read or write the database directly, so this is not a description of the DBMS.
Incorrectウ
This is the role of the business application program. It carries out the substance of the business processing, such as registering an order or checking a balance, and in the course of that work it issues requests to retrieve or update data whenever they are needed. In other words, it is the side that issues requests to the DBMS, not the side that receives and executes them. The requesting side and the receiving side have been swapped, which is why this choice is wrong.
Incorrectエ
This is the role of the communication control program (communication control software). It connects to clients over the network and takes charge of communication processing such as receiving request messages and sending response messages. What it handles is the exchange of data over the network, which has nothing to do with operating on the data inside the database, so it cannot be a description of the DBMS.
ここがポイント
- The role of the DBMS (database management system) is to accept data retrieval and update requests from application programs and actually operate on the data inside the database. It unifies data operations into a single point of entry and takes charge of concurrency control, keeping data consistent, and recovery from failures.
- Memorize the server-side software of an OLTP system as layers, one per role: communication control = communication with clients; transaction monitor = accepting requests and starting application programs; business application program = doing the business processing and issuing data requests; DBMS = actually performing the retrieval and updates on the database.
用語