41. Customers Who Bought Every Product

Difficulty: Hard · Topics: Joins, Aggregations, Filtering & Selection

Return the customer_id of every customer who bought all products listed in products. purchases may contain repeat purchases and products that are not in the catalogue (ignore those).

Row order does not matter; column names must match. Your code is graded on 3 test cases, including hidden edge cases.

Sample data

purchases

customer_id	product_id
1	a
1	b
1	c
2	a
2	b
3	a
3	b
3	c
3	a

products

product_id
a
b
c

Expected output

customer_id
1
3

Hints

Hint 1

This is "relational division": compare how many distinct catalogue products each customer bought with the catalogue size.

Hint 2

Keep only catalogue products with a left_semi join.

Hint 3

products.count() is a plain number you can compare against.

PySpark functions you'll practise

• groupBy
• agg
• count
• countDistinct
• join
• left_semi
• filter
• select
• distinct

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Browse

Topics: Window Functions · Joins · Aggregations · Pivot, Unpivot & Rollup · Arrays · Null Handling · Conditional Logic · Dates · Filtering & Selection · Strings

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