Right now we assume in the $minMaxScaler window function that is always sorted in ascending order ({_id/$x: 1}).

We also enforce that the document / range based bounds are such that the left bound is never positive, and the right bound is never positive (here)]

We should investigate in the behavior of specifying a sorting spec on a field in descending order ({_id/$x: -1}). What happens?

• does the query fail (properly?)
• does it run and produce incorrect results?

Its possible that the properly logic/enforcement is provided at the $setWindowFields level and no action is needed. Its possible, but unclear if we can remove the logic in at: https://github.com/10gen/mongo/blob/f391c90af149efd9bb7fd928b3f9e1e2076f6dc2/src/mongo/db/pipeline/window_function/window_function_expression.cpp#L380)]

Ultimately, we the behavior of $minMaxScaler should be in line with other window functions, as this question is not specific to $minMaxScaler (but we need to ensure were releasing this new window function with the expected behavior). We should run other window functions with a reversed sort order and observe the behavior.

Also, add the appropriate test cases (either expecting failure, or expecting correct results) to min_max_scaler_parsing.js / min_max_scaler_output_values.js.

Its possible that the behavior is different between Document and Range based bounds. See related ticket: SERVER-56450