diff --git a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/graph/SparkGraphImporterJob.java b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/graph/SparkGraphImporterJob.java
index c5223c1f6..633558906 100644
--- a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/graph/SparkGraphImporterJob.java
+++ b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/graph/SparkGraphImporterJob.java
@@ -27,6 +27,7 @@ public class SparkGraphImporterJob {
         final String inputPath = parser.get("sourcePath");
         final String hiveDbName = parser.get("hive_db_name");
 
+        spark.sql(String.format("DROP DATABASE IF EXISTS %s CASCADE", hiveDbName));
         spark.sql(String.format("CREATE DATABASE IF NOT EXISTS %s", hiveDbName));
 
         // Read the input file and convert it into RDD of serializable object
diff --git a/dhp-workflows/dhp-graph-provision/src/main/java/eu/dnetlib/dhp/graph/model/SortableRelationKey.java b/dhp-workflows/dhp-graph-provision/src/main/java/eu/dnetlib/dhp/graph/model/SortableRelationKey.java
new file mode 100644
index 000000000..ea56c6d12
--- /dev/null
+++ b/dhp-workflows/dhp-graph-provision/src/main/java/eu/dnetlib/dhp/graph/model/SortableRelationKey.java
@@ -0,0 +1,4 @@
+package eu.dnetlib.dhp.graph;
+
+public class SortableRelationKey {
+}
diff --git a/dhp-workflows/dhp-graph-provision/src/main/java/eu/dnetlib/dhp/graph/utils/RelationPartitioner.java b/dhp-workflows/dhp-graph-provision/src/main/java/eu/dnetlib/dhp/graph/utils/RelationPartitioner.java
new file mode 100644
index 000000000..0a7c6dcaf
--- /dev/null
+++ b/dhp-workflows/dhp-graph-provision/src/main/java/eu/dnetlib/dhp/graph/utils/RelationPartitioner.java
@@ -0,0 +1,4 @@
+package eu.dnetlib.dhp.graph.utils;
+
+public class RelationPartitioner {
+}
diff --git a/dhp-workflows/dhp-graph-provision/src/test/java/eu/dnetlib/dhp/graph/GraphJoinerTest.java b/dhp-workflows/dhp-graph-provision/src/test/java/eu/dnetlib/dhp/graph/GraphJoinerTest.java
new file mode 100644
index 000000000..e8c1c088c
--- /dev/null
+++ b/dhp-workflows/dhp-graph-provision/src/test/java/eu/dnetlib/dhp/graph/GraphJoinerTest.java
@@ -0,0 +1,4 @@
+package eu.dnetlib.dhp.graph;
+
+public class GraphJoinerTest {
+}