Weighted Variant Selection

A hard SQL interview practice problem on DataDriven. Write and execute real sql code with instant grading.

Domain

SQL

Difficulty

hard

Seniority

L5

Problem

The A/B testing platform uses rollout percentages to weight feature flag selection. Compute each flag's selection probability (its rollout divided by the total rollout across all flags) and its cumulative probability (the running sum of probabilities in rollout order).

Summary

Select a row using cumulative weight probabilities.

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