WIP: materialize graph as Hive DB, mergeAggregatorGraphs [added workflow node to drop the DB]

dhp-workflows/dhp-graph-mapper/src/main/resources/eu/dnetlib/dhp/oa/graph/merge/oozie_app/workflow.xml

@@ -64,12 +64,43 @@
         </property>
     </parameters>
 
-	<start to="fork_merge_graph"/>
+	<start to="should_drop_db"/>
 
     <kill name="Kill">
         <message>Action failed, error message[${wf:errorMessage(wf:lastErrorNode())}]</message>
     </kill>
 
+    <decision name="should_drop_db">
+        <switch>
+            <case to="fork_merge_graph">${wf:conf('outputGraphFormat') eq 'JSON'}</case>
+            <case to="reset_DB">${wf:conf('outputGraphFormat') eq 'HIVE'}</case>
+            <default to="reset_DB"/>
+        </switch>
+    </decision>
+
+    <action name="reset_DB">
+        <spark xmlns="uri:oozie:spark-action:0.2">
+            <master>yarn</master>
+            <mode>cluster</mode>
+            <name>reset_DB</name>
+            <class>eu.dnetlib.dhp.common.ResetHiveDbApplication</class>
+            <jar>dhp-graph-mapper-${projectVersion}.jar</jar>
+            <spark-opts>
+                --executor-memory ${sparkExecutorMemory}
+                --executor-cores ${sparkExecutorCores}
+                --driver-memory=${sparkDriverMemory}
+                --conf spark.extraListeners=${spark2ExtraListeners}
+                --conf spark.sql.queryExecutionListeners=${spark2SqlQueryExecutionListeners}
+                --conf spark.yarn.historyServer.address=${spark2YarnHistoryServerAddress}
+                --conf spark.eventLog.dir=${nameNode}${spark2EventLogDir}
+                --conf spark.sql.shuffle.partitions=7680
+            </spark-opts>
+            <arg>--dbName</arg><arg>${outputGraph}</arg>
+        </spark>
+        <ok to="fork_merge_graph"/>
+        <error to="Kill"/>
+    </action>
+    
     <fork name="fork_merge_graph">
         <path start="merge_publication"/>
         <path start="merge_dataset"/>