A NULL range column now matches CompareTo(null) > 0 in a query; Comparer treats null vs null as equal #261

Problem

Since #227's rewrite (ValueRangesQueryExpressionInterceptor.cs:230), rows whose nullable range or multirange column is NULL match r.Maybe.CompareTo(none) > 0 when none is null: the server returned 7 of 7. Before #227 they were excluded (NULL > NULL). In memory the call would throw a NullReferenceException on the null receiver, and Comparer<T>.Default.Compare(null, null) is 0, not positive. Found live by the final pre-release analysis on add665c (pass A).

Decision (maintainer, 2026-10-19)

A null receiver against a null operand compares equal, as Comparer<T>.Default does. Rows with a NULL column and a null operand match == 0, >= 0 and <= 0, and not > 0, < 0 or != 0. A NULL column against a non-null operand compares lower (null first), consistent with Comparer<T>.Default and the documented "null sorts first" rule. Work out the ±1 forms of #256 under the same rule.

Done when

RangeOrderParityTests has a nullable-column case with a null and a non-null operand for every comparison (0 and ±1 forms), and the server agrees with Comparer<T>.Default row for row, live. The docs' null sentence says how a NULL column compares.