Do not do SELECT count(*) FROM ... if pagination is not requested (#6098)

* Do not do `SELECT count(*) FROM ...` if pagination is not requested

* Update pagination.py

Co-authored-by: Tom Christie <tom@tomchristie.com>

Author: dmugtasimov

rest_framework/pagination.py

@@ -376,11 +376,11 @@ class LimitOffsetPagination(BasePagination):
     template = 'rest_framework/pagination/numbers.html'
 
     def paginate_queryset(self, queryset, request, view=None):
-        self.count = self.get_count(queryset)
         self.limit = self.get_limit(request)
         if self.limit is None:
             return None
 
+        self.count = self.get_count(queryset)
         self.offset = self.get_offset(request)
         self.request = request
         if self.count > self.limit and self.template is not None: