support lg_k in non-aggregate union
diff --git a/sql/datasketches_theta_sketch.sql b/sql/datasketches_theta_sketch.sql
index 2a8cfe8..eb46d6d 100644
--- a/sql/datasketches_theta_sketch.sql
+++ b/sql/datasketches_theta_sketch.sql
@@ -96,6 +96,10 @@
     AS '$libdir/datasketches', 'pg_theta_sketch_union'
     LANGUAGE C STRICT IMMUTABLE;
 
+CREATE OR REPLACE FUNCTION theta_sketch_union(theta_sketch, theta_sketch, int) RETURNS theta_sketch
+    AS '$libdir/datasketches', 'pg_theta_sketch_union'
+    LANGUAGE C STRICT IMMUTABLE;
+
 CREATE OR REPLACE FUNCTION theta_sketch_intersection(theta_sketch, theta_sketch) RETURNS theta_sketch
     AS '$libdir/datasketches', 'pg_theta_sketch_intersection'
     LANGUAGE C STRICT IMMUTABLE;