Database systems that store each relation in a separate operating system file…

2018

Database systems that store each relation in a separate operating system file may use the operating system’s authorization scheme, instead of defining a special scheme themselves. In this case, which of the following is false ?

  1. A.

    The administrator enjoys more control on the grant option.

  2. B.

    It is difficult to differentiate among the update, delete and insert authorizations.

  3. C.

    Cannot store more than one relation in a file.

  4. D.

    Operations on the database are speeded up as the authorization procedure is carried out at the operating system level.

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Correct answer: A

Answer: The administrator enjoys more control on the grant option. is false.

Explanation: When a DBMS maps each relation to a separate operating system file and relies on the OS authorization scheme, authorization is enforced at the file level using OS permissions (e.g., read/write/execute). These permissions are coarse-grained and do not provide database-specific grant semantics such as granting particular SQL operations or GRANT WITH GRANT OPTION. As a result, the database administrator does not have more fine-grained control over database grants compared to a DBMS-managed authorization scheme.

  • The administrator enjoys more control on the grant option: False — OS-level permissions are not designed for DB-specific grant semantics, so DB admins lose fine-grained control.

  • It is difficult to differentiate among the update, delete and insert authorizations: True — OS file permissions do not map directly to distinct SQL operations, so distinguishing these SQL-level privileges is hard.

  • Cannot store more than one relation in a file: True (in this usage context) — To apply OS-level permissions per relation, systems map each relation to its own file; storing multiple relations in the same file would prevent per-relation OS permissioning.

  • Operations on the database are speeded up as the authorization procedure is carried out at the operating system level: True (with caveats) — OS checks can be faster because they are handled by the OS, but this comes at the cost of coarser-grained control and loss of database-specific privilege semantics.

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