Spark SQL quiz

Test your Spark SQL knowledge with a free interactive quiz — 26 questions with answers and explanations. No signup needed to play.

What is `df.cache()` (or `df.persist()`) used for?

1. What is `df.cache()` (or `df.persist()`) used for?
2. What is a window function used for in Spark SQL?
3. What is a User-Defined Function (UDF) in Spark SQL?
4. How do you filter rows in a DataFrame?
5. How do you group and aggregate data?
6. What is Spark SQL?
7. What is schema inference, and when might you want an explicit schema instead?
8. What does `df.printSchema()` show?
9. What is a `SparkSession`?
10. How do you add a new computed column to a DataFrame?
11. What is the difference between a "transformation" and an "action" in Spark?
12. What does `df.select("name", "age")` do?

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