diff -r 11953d585a55 -r 24a20d2b8c84 cubicweb/server/ssplanner.py
--- a/cubicweb/server/ssplanner.py	Wed Mar 13 11:02:39 2019 +0100
+++ b/cubicweb/server/ssplanner.py	Wed Feb 19 19:49:01 2020 +0100
@@ -307,6 +307,11 @@
         return self.build_select_plan(plan, union)
 
 
+def prepare_plan(plan, schema, rqlhelper):
+    """Add steps to a plan to prepare it for execution"""
+    return SSPlanner(schema, rqlhelper).build_plan(plan)
+
+
 # execution steps and helper functions ########################################
 
 class Step(object):