Databricks Data Engineer Associate Question 296
Select 3A data engineering team is working on optimizing query performance for a Delta Lake table that is frequently queried on specific columns, such as 'region' and 'date'. How does Z-Ordering help improve performance in such scenarios?
- A
It clusters data in Delta Lake tables based on the specified columns, reducing the amount of data read during queries.
- B
It compresses the data in the Delta Lake table more effectively, leading to smaller file sizes and faster reads.
- C
It improves query performance by physically organizing data on disk to maximize locality for the specified columns.
- D
It automatically creates indexes for the specified columns, making filtering operations faster.
- E
It ensures that data is sorted within each partition to optimize the scan efficiency for the specified columns.
Show answer and explanation
Correct answers: A, C, E
Explanation
Z-Ordering is a data optimization technique in Delta Lake that reorders data files to optimize query performance on specific columns. It physically organizes data on disk to group similar values together, reducing the amount of data read during queries. While it does not compress data or create indexes, it ensures data is sorted within partitions, enhancing scan efficiency for the specified columns.
- A. Correct.
Z-Ordering clusters data in Delta Lake tables by re-ordering it based on specified columns, reducing the data scanned during queries that filter on those columns.
- B. Incorrect.
Z-Ordering does not directly compress data; compression is handled separately in Delta Lake.
- C. Correct.
Z-Ordering improves performance by physically organizing data on disk to group similar values of the specified columns together, enhancing locality and reducing the amount of data read.
- D. Incorrect.
Z-Ordering does not create indexes for the specified columns. Delta Lake does not support traditional indexing mechanisms.
- E. Correct.
Z-Ordering ensures that data is sorted within each partition for the specified columns, optimizing the efficiency of scan operations on those columns.