Unique Cardinality with countDistinct()

How do we count the exact number of distinct customer buyers who placed orders?

Intermediate⏱ 2 Minutes⭐ 390 XP

🤔 THE QUESTION

How do we count the exact number of distinct customer buyers who placed orders?

💡 WHAT IS IT?

countDistinct() calculates the exact number of unique values in a Column across all distributed partitions.

🎯 WHAT IS IT USED FOR?

Unique buyer metrics, daily active user counts, and cardinality analysis for indexing.

💻 EXAMPLE

from pyspark.sql.functions import col, countDistinct

df.select(countDistinct(col("customer_id")).alias("unique_buyers")).show()

Practice typing production-grade PySpark code for Unique Cardinality with countDistinct().