Module assessment

1.

What is the purpose of running the ANALYZE TABLE command in Azure Databricks?

To create a backup of the table before making changes

To compute statistics that help the query optimizer choose efficient execution plans

To validate that all data types in the table are correctly defined

2.

Which data type should be used when storing financial amounts that require exact precision in calculations?

DOUBLE

DECIMAL(p,s)

FLOAT

3.

Which SQL clause filters duplicate rows directly from a window function result without requiring a subquery?

WHERE

HAVING

QUALIFY

4.

What is the difference between a LEFT SEMI JOIN and a LEFT JOIN?

LEFT SEMI JOIN returns all columns from both tables while LEFT JOIN returns only left table columns

LEFT SEMI JOIN returns only left table rows that have matches in the right table, without including right table columns

LEFT SEMI JOIN includes NULL values for non-matching rows while LEFT JOIN excludes them

5.

When should a data engineer use the UNPIVOT transformation?

To convert multiple columns into rows for analysis or normalization

To create a summary table with row values displayed as column headers

To merge two tables based on matching key columns

6.

Which loading operation should be used to update existing records while inserting new ones in a single statement?

INSERT INTO with append mode

INSERT OVERWRITE

MERGE INTO

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