You can use feature functions in sort expressions. Most feature functions can be used only in fine sort expressions. You can combine various syntax and clauses to perform complex sorts.
static_bm25: returns the static text relevance that indicates the matching degree between the query and document
The return value is of the FLOAT type. Valid values: [0,1].
Scenario 1: You can use the static_bm25() function in a rough sort expression to calculate the text relevance.
You can use this feature function in rough sort expressions.