Join Duplicate Fanout - SQL for Data Analysis

Duplicate join keys create one output row for each matching pair.

highlighted = computed this step

OrderLines input

Start with order lines where a product key repeats on the left.

\text{OrderLines}

Products also has a repeated product key.

\text{Products}

INNER JOIN pairs every equal key across the two bags.

\text{OrderLines JOIN Products}

Each duplicate left row pairs with each duplicate right row.

\text{fanout output}