PROFESSIONAL-CLOUD-DATABASE-ENGINEER · Question #17
You released a popular mobile game and are using a 50 TB Cloud Spanner instance to store game data in a PITR-enabled production environment. When you analyzed the game statistics, you realized that…
The correct answer is A. If the corruption is significant, use backup and restore, and specify a recovery timestamp. E. If the corruption is insignificant, perform a stale read and specify a recovery timestamp. Write the. Cloud Spanner with PITR (Point-in-Time Recovery) enabled supports two recovery strategies depending on the scale of corruption. If corruption is SIGNIFICANT (affecting large portions of data), use backup and restore with a specific recovery timestamp (A) - this restores the…
Question
You released a popular mobile game and are using a 50 TB Cloud Spanner instance to store game data in a PITR-enabled production environment. When you analyzed the game statistics, you realized that some players are exploiting a loophole to gather more points to get on the leaderboard. Another DBA accidentally ran an emergency bugfix script that corrupted some of the data in the production environment. You need to determine the extent of the data corruption and restore the production environment. What should you do? (Choose two.)
Options
- AIf the corruption is significant, use backup and restore, and specify a recovery timestamp.
- BIf the corruption is significant, perform a stale read and specify a recovery timestamp. Write the
- CIf the corruption is significant, use import and export.
- DIf the corruption is insignificant, use backup and restore, and specify a recovery timestamp.
- EIf the corruption is insignificant, perform a stale read and specify a recovery timestamp. Write the
How the community answered
(37 responses)- A84% (31)
- B3% (1)
- C8% (3)
- D5% (2)
Explanation
Cloud Spanner with PITR (Point-in-Time Recovery) enabled supports two recovery strategies depending on the scale of corruption. If corruption is SIGNIFICANT (affecting large portions of data), use backup and restore with a specific recovery timestamp (A) - this restores the entire database to a known-good state before the corrupt script ran. If corruption is INSIGNIFICANT (affecting only a few rows), a full restore of a 50 TB database would be extremely costly and time-consuming. Instead, perform a stale read at the recovery timestamp (E) to retrieve the pre-corruption values for only the affected rows, then write those values back - a much more targeted and efficient fix. Option B is wrong because stale reads are only practical for small-scale corruption. Option D is wrong because backup/restore on a 50 TB instance for minor corruption is disproportionately expensive and disruptive. Option C (import/export) has no PITR capability and is not suited for recovery scenarios.
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