The web team wants a second set of checks on its order documents and customer change feed. The queries must keep their output grain clear: some return one row per document, some one per tag, and one returns a single selected update for each customer. No task introduces a new construct.
Read optional fields before grouping them. An empty tags array should remain visible when you count tags per order, but it should not create a fake tag in a popularity report. A timestamp tie in the customer feed also needs the tie rule stated in the request. Write rules for the underlying data rather than copying values from the result grid.