Databricks Data Engineer Associate Question 283
Single answerA data engineering team is working on a Delta table named 'sales_data' in Databricks. They accidentally performed an UPDATE operation that introduced incorrect data. The team wants to roll back the table to a previous version where the data was accurate. Which approach should they use?
- A
Use the RESTORE command with the Delta table's desired version.
- B
Use the VACUUM command to revert to the desired version of the Delta table.
- C
Use the DESCRIBE HISTORY command to identify the correct version and then use the TIME TRAVEL feature to query the desired version.
- D
Use the DELETE command to remove the incorrect rows and manually reinsert the correct data.
Show answer and explanation
Correct answer: C
Explanation
Delta Lake provides a robust mechanism for rolling back to previous versions of a table using the TIME TRAVEL feature. By first using the DESCRIBE HISTORY command, the team can identify the desired version and then query or restore that version as needed. This method ensures accuracy and avoids manual errors.
- A. Incorrect.
The RESTORE command is not currently available in Databricks Delta Lake. Instead, Delta Lake supports time travel to access previous versions of the table.
- B. Incorrect.
The VACUUM command is used to clean up old data files and cannot be used to revert a Delta table to a previous version.
- C. Correct.
The DESCRIBE HISTORY command allows you to view the history of changes to the Delta table, and the TIME TRAVEL feature can be used to query a previous version of the table by specifying a version number or timestamp.
- D. Incorrect.
The DELETE command is not a feasible approach for rolling back the table, as it requires manual intervention and does not ensure the accuracy of all the data.