IPA IP 2021 Question 62
A question IPA Japan published in 令和3年度 ITパスポート試験 公開問題 問62, translated into English. ITPEC is based on the same exams.
In an account transfer of a financial system, the consistency of the database is maintained by ensuring that, for the withdrawal processing from the transfer source account and the deposit processing to the transfer destination account, either both of the processes are executed or neither of them is executed. What is the term for handling such a series of processes for a database as a transaction and confirming the updated content of the database when the processing has been completed without inconsistency?
Explanation
Commit — confirming a transaction's updates in the database once all of its processes have finished without inconsistency.
A transaction is a series of processes that must succeed or fail as one unit (atomicity). In the account transfer, the withdrawal and the deposit form one transaction: if only the withdrawal ran, money would vanish. When both finish normally, the DBMS commits, and the updates become permanent. If either fails, it rolls back, returning the database to its state before the transaction began.
Answer (a)
Why not others:
- •(b) Schema — the definition of the database's structure (tables, items, relationships), not an operation on a transaction
- •(c) Roll forward — recovery after a storage failure: the backup is restored and the update logs (after-images) are applied to bring it up to date
- •(d) Lock — exclusive control that stops other transactions from updating data while one transaction is using it
Key rule: A transaction ends in a commit (make all its updates permanent) or a rollback (undo them all); roll forward is recovery from a backup plus the log.
Databases · AI-written, may contain errors
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.