IPA IP 2020 Question 64

Topic: Databases

A question IPA Japan published in 令和2年度 10月 ITパスポート試験 公開問題 問64, translated into English. ITPEC is based on the same exams.

Among the descriptions A through C concerning data processing, which of the following lists all and only the effects obtained by introducing a DBMS?

AEven when multiple programs access the same data at the same time, consistency is maintained.BSince the DBMS decides the order of processing according to the priority of each transaction, the response time of real-time processing becomes shorter.CSince the efficiency of the page management of virtual memory improves, the access time to data becomes constant regardless of the amount of data.

Explanation

A only — a DBMS keeps shared data consistent under concurrent access; scheduling by priority and virtual memory are not what it provides.

  • •A: appropriate. The DBMS's exclusive control (locking) and transaction management stop simultaneous updates from overwriting each other, so the data stays consistent however many programs use it.
  • •B: not an effect. Deciding the execution order by priority to meet real-time deadlines is task scheduling by the OS, especially a real-time OS. A DBMS serialises conflicting transactions, which can make some of them wait.
  • •C: not an effect. Page management of virtual memory is an OS function, and no DBMS makes access time independent of the amount of data: the more data, the more there is to search, which is why indexes exist.

Answer (a)

Why not others:

  • •(b) — adds C, which credits the DBMS with the OS's virtual memory and a constant access time no DBMS can give
  • •(c) — B describes the OS's priority scheduling, and A, the real effect, is missing
  • •(d) — both B and C describe OS functions, and A is missing

Key rule: A DBMS gives data independence, integrity, concurrency control and recovery; task scheduling and virtual memory belong to the OS.

Databases · AI-written, may contain errors

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This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.