How To Efficiently Finding Top N Rows Of Every Group

Motivation:

You search for an efficient approach that finds top N rows of every group.

Note:

If you are not familiar with the ROW_NUMBER() window function then consider reading How to efficiently assign a database temporary sequence of values to rows before continuing.

Description:

This application is an example of finding top N rows of every group via the ROW_NUMBER() window function.

Key points:

Write a native query relying on ROW_NUMBER() window function as in the code below:

Testing time:

Tam Ta Da Dam! :) The complete application is available on GitHub.

If you need a deep dive into the performance recipes exposed in this repository then I am sure that you will love my book "Spring Boot Persistence Best Practices".