Databricks Data Engineer Professional Question 48
Select 4You are tasked with processing a large dataset of IoT sensor data using Databricks. The dataset arrives daily as batch files, and your goal is to create an optimized Delta Lake table to support both historical analysis and real-time incremental updates. Which of the following steps should you take to achieve this?
- A
Use Auto Loader to ingest the daily batch files, and write the data directly to a Delta table with the 'merge' option.
- B
Partition the Delta Lake table by a relevant column, such as 'event_date', to improve query performance.
- C
Use Z-Ordering on the 'sensor_id' column if it is frequently used in query filters.
- D
Enable Delta Lake's Change Data Feed (CDF) to track changes in the table for incremental updates.
- E
Use the OPTIMIZE command to compact small files and improve table performance.
Show answer and explanation
Correct answers: B, C, D, E
Explanation
To process large datasets in Delta Lake for both historical and incremental use cases, it is critical to optimize the table's structure and performance. Partitioning and Z-Ordering improve query efficiency, while Change Data Feed enables incremental processing. The OPTIMIZE command ensures that the table remains performant by compacting small files.
- A. Incorrect.
This option is incorrect because Auto Loader is primarily used for streaming ingestion. For batch files, you would typically use other mechanisms like COPY INTO or Spark batch jobs, and 'merge' is not directly applicable in this context.
- B. Correct.
Partitioning the Delta Lake table by relevant columns, such as 'event_date', improves query performance by reducing the amount of data scanned during queries.
- C. Correct.
Z-Ordering helps optimize read performance for common query filters, such as 'sensor_id', by clustering data on disk for faster access.
- D. Correct.
Enabling Change Data Feed (CDF) allows you to efficiently track changes to the Delta table, which is essential for supporting incremental updates.
- E. Correct.
The OPTIMIZE command is used to compact small files in Delta Lake, improving performance for both batch and incremental operations.