diff --git a/doc/discovery_functions.md b/doc/discovery_functions.md
index 356ddd3..697a163 100644
--- a/doc/discovery_functions.md
+++ b/doc/discovery_functions.md
@@ -228,7 +228,7 @@ SELECT * FROM cdb_observatory.OBS_GetAvailableDenominators(
 WHERE valid_timespan IS True;
 ```
 
-## OBS_GetAvailableGeometries(bounds, filter_tags, numer_id, denom_id, timespan)
+## OBS_GetAvailableGeometries(bounds, filter_tags, numer_id, denom_id, timespan, number_geometries)
 
 Return available geometries within a boundary and with the specified
 `filter_tags`.
@@ -242,6 +242,7 @@ filter_tags | Text[] | a list of filters.  Only geometries for which all of thes
 numer_id | Text | the ID of a numerator to check whether the geometry is valid against.  Will not reduce length of returned table, but will change values for `valid_numer` (optional)
 denom_id | Text | the ID of a denominator to check whether the geometry is valid against.  Will not reduce length of returned table, but will change values for `valid_denom` (optional)
 timespan | Text | the ID of a timespan to check whether the geometry is valid against.  Will not reduce length of returned table, but will change values for `valid_timespan` (optional)
+number_geometries | Integer | Number of geometries of the source data in order to calculate more accurately the score value to know which geometry fits better with the provided extent. (optional)
 
 #### Returns
 
diff --git a/src/pg/observatory.control b/src/pg/observatory.control
index 149b6a5..84e7094 100644
--- a/src/pg/observatory.control
+++ b/src/pg/observatory.control
@@ -1,5 +1,5 @@
 comment = 'CartoDB Observatory backend extension'
-default_version = '1.7.0'
+default_version = '1.8.0'
 requires = 'postgis'
 superuser = true
 schema = cdb_observatory
diff --git a/src/pg/sql/42_observatory_exploration.sql b/src/pg/sql/42_observatory_exploration.sql
index bbd5e56..272eec2 100644
--- a/src/pg/sql/42_observatory_exploration.sql
+++ b/src/pg/sql/42_observatory_exploration.sql
@@ -323,7 +323,8 @@ CREATE OR REPLACE FUNCTION cdb_observatory.OBS_GetAvailableGeometries(
   filter_tags TEXT[] DEFAULT NULL,
   numer_id TEXT DEFAULT NULL,
   denom_id TEXT DEFAULT NULL,
-  timespan TEXT DEFAULT NULL
+  timespan TEXT DEFAULT NULL,
+  number_geoms INTEGER DEFAULT NULL
 ) RETURNS TABLE (
   geom_id TEXT,
   geom_name TEXT,
@@ -390,15 +391,16 @@ BEGIN
       FROM observatory.obs_meta_geom o
       WHERE %s (geom_tags ?& $4 OR CARDINALITY($4) = 0)
     ), scores AS (
-      SELECT * FROM cdb_observatory._OBS_GetGeometryScores($5,
-        (SELECT ARRAY_AGG(geom_id) FROM available_geoms)
+      SELECT * FROM cdb_observatory._OBS_GetGeometryScores(bounds => $5,
+        filter_geom_ids => (SELECT ARRAY_AGG(geom_id) FROM available_geoms),
+        desired_num_geoms => $6::integer
       )
     ) SELECT DISTINCT ON (geom_id) available_geoms.*, score, numtiles, notnull_percent, numgeoms,
              percentfill, estnumgeoms, meanmediansize
       FROM available_geoms, scores
       WHERE available_geoms.geom_id = scores.column_id
   $string$, geom_clause)
-  USING numer_id, denom_id, timespan, filter_tags, bounds;
+  USING numer_id, denom_id, timespan, filter_tags, bounds, number_geoms;
   RETURN;
 END
 $$ LANGUAGE plpgsql;