Secondary Calculation / Usage calculated field in a another calculation

Suppose we want to build a Pareto chart https://en.wikipedia.org/wiki/Pareto_chart. To do so we need a tow way calculation. First a share of a cluster of total value/sum and a second calculation with a running sum of these shares.

An SQL solution is not always possible, since MySQL 5 (including AWS Aurora DB) and prior does not support analytical functions like `sum() over partition()`.

Here is a sample how it can be build with Tableau. https://help.tableau.com/current/pro/desktop/en-us/pareto.htm

:arrow_down: Please click the :+1: reaction instead of leaving a `+1` or `update?` comment

Review the Pareto chart example and the requested two-stage calculation: a grouped share followed by a running sum. Define how these calculations should work without analytical SQL functions and what output would demonstrate that the feature is complete.

Written by the indexing model from the issue text.