Managing Implementation and Ensuring Solution and Operations Reliability →hardMultiple ChoiceObjective-mapped
Google PCA Practice Question: Managing Implementation and Ensuring Solution and Operations Reliability
An e-commerce platform uses Cloud Spanner for order processing. The operations team notices that a recent schema change caused a spike in latency. They need to quickly revert to the previous schema without losing any data. What is the fastest way to achieve this?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Restore the database from a backup taken before the schema change, using point-in-time recovery.
Cloud Spanner does not support automatic schema rollback. The best approach is to use database migration tools like Skipper or use versioned migrations. However, Spanner supports creating a new table with the old schema and copying data. The fastest way to revert a schema change is to restore from a backup that was taken before the change. Cloud Spanner supports point-in-time recovery (PITR) within the retention period (7 days). If a backup exists, restore it to a new database and redirect traffic. Rolling back via DDL statements is possible but may be complex if data has been added or altered.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Manually write DDL statements to revert the schema, and use a script to fix any data inconsistencies.
Why it's wrong here
Manual rollback is error-prone and slow; data may have been modified.
- ✗
Export the database, drop and recreate the database with the old schema, and import the data.
Why it's wrong here
Export/import is slow and could cause data loss for changes after the schema change.
- ✗
Use Cloud Spanner's built-in DDL rollback feature to revert the schema change.
Why it's wrong here
Spanner does not have a built-in DDL rollback; DDL changes are immediate and irreversible.
- ✓
Restore the database from a backup taken before the schema change, using point-in-time recovery.
Why this is correct
Restoring from a backup before the change is the fastest way to revert schema and data.
Go deeper
Related to this question
Learn chapter
Introduction to Google Cloud Platform
Key term
Cloud Spanner
Cloud Spanner is a fully managed, globally distributed relational database service from Google Cloud that combines the benefits of relational database structure with horizontal scalability and strong consistency.
Key term
Latency
Latency is the time delay between a request being sent over a network and the response being received, often measured in milliseconds.
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Written by Johnson Ajibi, MSc IT Security
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