Removed Restrictions on Aggregate Function Combinators

Why it matters

This feature was created to increase flexibility and expressiveness in aggregation queries by enabling the use of multiple combinators together. It solves the problem of limited functionality when combining aggregate function modifiers, offering users more powerful ways to customize aggregations according to different conditions and grouping criteria.

How to use it

Use aggregate function combinators in any valid combination within ClickHouse queries. For example, you can write queries using avgForEachIf or avgIfForEach aggregate functions to apply averages with both per-element conditions (ForEach) and conditional filtering (If). Example usage can be:

SELECT avgForEachIf(column, condition) FROM table

or

SELECT avgIfForEach(column, condition) FROM table