PySpark Aggregations

18 interview problems on groupBy, agg, percentiles and conditional metrics, from easy to hard.

• Average Salary by Department · Easy · Aggregations
• Departments with Large Teams · Easy · Aggregations
• Word Count · Medium · Arrays
• Pivot Quarterly Revenue · Medium · Pivot, Unpivot & Rollup
• Conditional Aggregation · Medium · Aggregations
• Entry and Exit Pages (MAX_BY / MIN_BY) · Medium · Aggregations
• New Users per Day · Medium · Aggregations
• Median and 90th Percentile · Medium · Aggregations
• Sorted Distinct Purchase List · Medium · Arrays
• Three-Day Login Streak · Hard · Window Functions
• Subtotals with ROLLUP · Hard · Pivot, Unpivot & Rollup
• All Combinations with CUBE · Hard · Pivot, Unpivot & Rollup
• Pivot with Several Aggregations · Hard · Pivot, Unpivot & Rollup
• Consecutive Status Runs (Gaps and Islands) · Hard · Window Functions
• Fill Missing Dates (Calendar Spine) · Hard · Joins
• Customers Who Bought Every Product · Hard · Joins
• Conversion Funnel · Hard · Aggregations
• Monthly Retention by Cohort · Hard · Joins

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

Difficulty: Easy · Medium · Hard · PySpark interview roadmap · All problems