Aggregate Daily Returns Query | Dataford Interview Questions

Your question is Aggregate Daily Returns Query. Start with the requirements and the two tables on the right.

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Problem

Aqr's portfolio tracking system stores portfolio metadata separately from daily return observations. Write a PostgreSQL query that summarizes active portfolios between 2025-01-01 and 2025-01-03.

Requirements

Join portfolio metadata to return observations and exclude inactive portfolios.
Return one row per portfolio and return date, with the summed daily return percentage.
Include the number of non-null return observations and the number of positive observations.
Sort results by return date ascending, then portfolio name ascending. Treat a day containing only null return values as a zero aggregate return.

Schema

portfolios

Column	Type	Description
portfolio_idPK	INT	Unique portfolio identifier
portfolio_name	VARCHAR(100)	Aqr portfolio name
portfolio_type	VARCHAR(50)	Portfolio strategy classification
is_active	BOOLEAN	Whether the portfolio is currently active

portfolio_return_observations

Column	Type	Description
observation_idPK	INT	Unique return observation identifier
portfolio_id	INT	Portfolio associated with the observation
return_date	DATE	Date of the return observation
return_pct	DECIMAL(10,6)	Return percentage for the observation