Oracle Backup Types — Consistent vs. Inconsistent In Oracle backup terminology, which backup type ensures that all uncommitted changes have been removed from the datafiles (that is, the database is in a transaction-consistent state at the backup point)?

Introduction:
Backups can be taken while the database is open or closed. The resulting recovery steps depend on whether the backup captures datafiles in a transaction-consistent state. This question asks you to identify the backup type where uncommitted changes have been cleared from the datafiles.

Given Data / Assumptions:

• A consistent backup is taken when the database is cleanly closed or quiesced.
• An inconsistent backup is taken while the database is open and requires redo to recover consistency.
• Terminology distinguishes consistency from scope (full vs. incremental).

Concept / Approach:
In a consistent backup, the datafiles on disk reflect only committed transactions as of the checkpoint, so recovery does not need to apply redo to make blocks consistent. In an inconsistent backup, redo application (media recovery) is necessary to roll forward uncommitted and committed changes to a consistent point. Therefore, the type that has already removed uncommitted changes is the consistent backup.

Step-by-Step Solution:
1) Map “uncommitted changes removed” to transaction-consistent datafiles.2) Recognize this corresponds to a consistent backup (typically taken with the database closed).3) Select “Consistent backup.”

Verification / Alternative check:
Oracle backup and recovery documentation explains that only inconsistent backups require redo application to reach a consistent point-in-time.

Why Other Options Are Wrong:

• Full / Differential / Cumulative incremental: These describe scope, not consistency.
• Inconsistent backup: Requires redo to become consistent; the opposite of the stated condition.

Common Pitfalls:
Confusing “full” with “consistent.” You can have a full backup that is either consistent or inconsistent depending on database state at backup time.

Final Answer:
Consistent backup