Grouping & Unnesting

Aggregations and unnesting allow you to return results at a different granularity than the input data.

This is particularly useful when you want to report metrics at a coarse level, such as country level instead of individual records.

Single-key aggregations

Key aggregation concepts:

• FILTER clauses: SUM(price) FILTER (WHERE condition) applies conditions during aggregation
• GROUP BY in aggregates: GROUP BY category groups the aggregation by specified columns
• Aggregate functions: SUM(), COUNT(), AVG(), MAX(), MIN()

Note: FeatureQL uses aggregate functions with built-in GROUP BY syntax rather than SQL's separate GROUP BY clause.

Multi-key aggregations

Multi-key grouping patterns:

• Multiple grouping columns: GROUP BY category, item_cat within aggregate functions
• Complex aggregates: Combine multiple aggregate functions
• Conditional aggregation: Use FILTER (WHERE condition) within aggregates

Other examples

Unnesting

Here's an example of how to use UNNEST to unnest an array of rows into a table of rows.

Unnesting an array of scalars

Unnesting an array of rows

Unnesting then grouping by

Unnesting with ordinality

Unnesting with many levels

Unnesting with other features forbidden