Merge pull request #22063 from ClickHouse/tuple-null-in

Allow to search tuple of NULLs in a set

src/Interpreters/convertFieldToType.cpp

@@ -377,6 +377,11 @@ Field convertFieldToType(const Field & from_value, const IDataType & to_type, co
     else if (const auto * nullable_type = typeid_cast<const DataTypeNullable *>(&to_type))
     {
         const IDataType & nested_type = *nullable_type->getNestedType();
+
+        /// NULL remains NULL after any conversion.
+        if (WhichDataType(nested_type).isNothing())
+            return {};
+
         if (from_type_hint && from_type_hint->equals(nested_type))
             return from_value;
         return convertFieldToTypeImpl(from_value, nested_type, from_type_hint);

tests/queries/0_stateless/01774_tuple_null_in.reference

+0
+0

tests/queries/0_stateless/01774_tuple_null_in.sql

+SELECT (NULL, NULL) = (8, 0) OR (NULL, NULL) = (3, 2) OR (NULL, NULL) = (0, 0) OR (NULL, NULL) = (3, 1);
+SELECT (NULL, NULL) IN ((NULL, 0), (3, 1), (3, 2), (8, 0), (NULL, NULL));