Seeking Guidance on Storage Models for Frequently Executed SQL Statement

An application frequently executes the following prepared statement in SQL:

SELECT AVG(StockUnits)
FROM PRODUCT;

I'm currently exploring the most suitable storage model for the database architecture. After some research, the term "Decomposition Storage Model" has come up, but could anyone help me understand why the "Decomposition Storage Model" might be particularly well-suited for handling the mentioned SQL statement? Any advice, explanations, or pointers to relevant resources would be highly appreciated.