fix: set proper default traversals

jina/drivers/querylang/reverse.py

@@ -21,7 +21,7 @@ class ReverseQL(QuerySetReader, BaseRecursiveDriver):
         will reverse the order of the documents returned by the `Chunk2DocRankerDriver` before sending them to the next `Pod`
     """
 
-    def __init__(self, traversal_paths: Tuple[str] = ('c',), *args, **kwargs):
+    def __init__(self, traversal_paths: Tuple[str] = ('r',), *args, **kwargs):
         super().__init__(traversal_paths=traversal_paths, *args, **kwargs)
 
     def _apply_all(self, docs: 'DocumentSet', *args, **kwargs) -> None:

jina/drivers/querylang/select.py

@@ -21,7 +21,7 @@ class ExcludeQL(QuerySetReader, BaseRecursiveDriver):
         ExcludeQL will avoid `buffer` and `chunks` fields to be sent to the next `Pod`
     """
 
-    def __init__(self, fields: Union[Tuple, str], traversal_paths: Tuple[str] = ('c',), *args, **kwargs):
+    def __init__(self, fields: Union[Tuple, str], traversal_paths: Tuple[str] = ('r',), *args, **kwargs):
         """
 
         :param fields: the pruned field names in tuple

jina/drivers/querylang/sort.py

@@ -32,7 +32,7 @@ class SortQL(QuerySetReader, BaseRecursiveDriver):
         `SortQL` will ensure that only the documents are sorted by the score value before slicing the first top 50 documents
     """
 
-    def __init__(self, field: str, reverse: bool = False, traversal_paths: Tuple[str] = ('c',), *args, **kwargs):
+    def __init__(self, field: str, reverse: bool = False, traversal_paths: Tuple[str] = ('r',), *args, **kwargs):
         """
         :param field: the value of the field drives the sort of the iterable docs
         :param reverse: sort the value from big to small