Databricks Data Engineer Associate Question 307
Select 2Which of the following types of files does the OPTIMIZE command in Databricks primarily compact?
- A
Small files generated by frequent writes or updates to a Delta table
- B
Large files exceeding the configured file size threshold
- C
Files stored in the Parquet format but not managed by Delta Lake
- D
Files created by Delta Lake operations such as MERGE or UPDATE
- E
Files from external systems like CSV or JSON imported into a Delta table
Show answer and explanation
Correct answers: A, D
Explanation
The OPTIMIZE command in Databricks is a Delta Lake feature that compacts small files generated by frequent writes, updates, or operations like MERGE into fewer, larger files. This improves query performance and reduces overhead. It is specifically designed for Delta Lake-managed tables, not for non-Delta or external file formats.
- A. Correct.
Correct: The OPTIMIZE command is designed to compact small files into fewer, larger files for improved read performance and efficiency.
- B. Incorrect.
Incorrect: The OPTIMIZE command does not target large files; it is specifically used to address the issue of too many small files.
- C. Incorrect.
Incorrect: OPTIMIZE only works on Delta Lake-managed tables, not on files outside the Delta Lake framework.
- D. Correct.
Correct: Operations such as MERGE or UPDATE in Delta Lake can generate many small files, which the OPTIMIZE command can compact.
- E. Incorrect.
Incorrect: While imported files like CSV or JSON can be part of a Delta table, OPTIMIZE works specifically on Delta Lake-managed files, not directly on the raw imported files.