diff --git a/scripts-available/CDB_Overviews.sql b/scripts-available/CDB_Overviews.sql
index 2540c4e..987f6c5 100644
--- a/scripts-available/CDB_Overviews.sql
+++ b/scripts-available/CDB_Overviews.sql
@@ -363,14 +363,14 @@ $$ LANGUAGE PLPGSQL STABLE;
 -- Experimental Overview reduction method for point datasets.
 -- It clusters the points using a grid, then aggregates the point in each
 -- cluster into a point at the centroid of the clustered records.
--- Scope: public.
+-- Scope: private.
 -- Parameters:
 --   reloid original table (can be the base table of the dataset or an existing
 --   overview) from which the overview is being generated.
 --   ref_z Z level assigned to the original table
 --   overview_z Z level of the overview to be generated, must be smaller than ref_z
 -- Return value: Name of the generated overview table
-CREATE OR REPLACE FUNCTION CDB_GridCluster_Reduce_Strategy(reloid REGCLASS, ref_z INTEGER, overview_z INTEGER)
+CREATE OR REPLACE FUNCTION _CDB_GridCluster_Reduce_Strategy(reloid REGCLASS, ref_z INTEGER, overview_z INTEGER)
 RETURNS REGCLASS
 AS $$
   DECLARE
@@ -461,7 +461,7 @@ $$ LANGUAGE PLPGSQL;
 CREATE OR REPLACE FUNCTION CDB_CreateOverviews(
   reloid REGCLASS,
   refscale_strategy regproc DEFAULT '_CDB_Feature_Density_Ref_Z_Strategy'::regproc,
-  reduce_strategy   regproc DEFAULT 'CDB_GridCluster_Reduce_Strategy'::regproc
+  reduce_strategy   regproc DEFAULT '_CDB_GridCluster_Reduce_Strategy'::regproc
 )
 RETURNS text[]
 AS $$