--- a/artifacts/src/main/java/org/dive4elements/river/artifacts/services/DynamicMainValuesTimeRangeDeterminationService.java	Wed Aug 15 13:59:09 2018 +0200
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/services/DynamicMainValuesTimeRangeDeterminationService.java	Wed Aug 15 14:34:23 2018 +0200
@@ -25,6 +25,7 @@
 import org.dive4elements.river.model.Gauge;
 import org.dive4elements.river.model.River;
 import org.dive4elements.river.model.sinfo.DailyDischargeValue;
+import org.dive4elements.river.model.sinfo.DailyDischargeValue.MinMax;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.NodeList;
@@ -92,18 +93,15 @@
 
         for (final Gauge gauge : gauges) {
 
-            final List<DailyDischargeValue> qdvsGlobal = DailyDischargeValue.getGlobalMinMax(gauge);
-            if (qdvsGlobal == null) {
-
+            final Date minGlobalForGauge = DailyDischargeValue.getGlobalMinMax(gauge, MinMax.min);
+            final Date maxGlobalForGauge = DailyDischargeValue.getGlobalMinMax(gauge, MinMax.max);
+            if (minGlobalForGauge == null || maxGlobalForGauge == null) { // der Fall, dass nur eins von beiden null ist, kann eigentlich nciht vorkommen
                 gaugeResults.add(new GaugeInfoResult.GaugeInfo(getMsg(meta, "bundu.wst_no_data_at_all"), gauge, null, null));
                 // TODO : wenn der Workflow abgebrochen werden soll, GlobalErrorMsg setzen, dass mind. ein Pegel überhaupt keine Daten
                 // hat (der Mechnismus auf Client-Seite ist schon implementiert)
 
                 continue;
             }
-            assert qdvsGlobal.size() == 2;
-            final Date minGlobalForGauge = qdvsGlobal.get(0).getDay();
-            final Date maxGlobalForGauge = qdvsGlobal.get(1).getDay();
 
             if (minGlobalForGauge.getTime() > startTime.getTime())
                 min = minGlobalForGauge;

--- a/backend/src/main/java/org/dive4elements/river/model/sinfo/DailyDischargeValue.java	Wed Aug 15 13:59:09 2018 +0200
+++ b/backend/src/main/java/org/dive4elements/river/model/sinfo/DailyDischargeValue.java	Wed Aug 15 14:34:23 2018 +0200
@@ -11,7 +11,6 @@
 package org.dive4elements.river.model.sinfo;
 
 import java.io.Serializable;
-import java.util.ArrayList;
 import java.util.Date;
 import java.util.List;
 
@@ -50,6 +49,10 @@
         DAY, DISCHARGE;
     }
 
+    public enum MinMax {
+        min, max
+    }
+
     /***** FIELDS *****/
 
     private static final long serialVersionUID = -6192738825193230784L;
@@ -139,22 +142,17 @@
     /**
      * Selects from the database the daily discharge, puts the first and the last into a List (min, max day)
      */
-    public static List<DailyDischargeValue> getGlobalMinMax(final Gauge gauge) {
+
+    public static Date getGlobalMinMax(final Gauge gauge, final MinMax minmax) {
         final Session session = SessionHolder.HOLDER.get();
-        final Query query = session
-                .createQuery("SELECT v" + " FROM DailyDischargeValue AS v JOIN v.dailyDischarge AS s" + " WHERE (s.gauge.id=:gaugeid)  ORDER BY day");
+        final Query query = session.createQuery(
+                "SELECT " + minmax.toString() + "(v.day) " + " FROM DailyDischargeValue AS v JOIN v.dailyDischarge AS s" + " WHERE (s.gauge.id=:gaugeid)");
         query.setParameter("gaugeid", gauge.getId());
-        return minMaxFromDbResultHelper(query.list());
+        final List<Date> list = query.list();
+        if (list != null && list.size() == 1) {
+            return list.get(0);
+        }
+        return null;
     }
 
-    private static List<DailyDischargeValue> minMaxFromDbResultHelper(final List<DailyDischargeValue> values) {
-        if (values != null && values.size() > 1) {
-            final List<DailyDischargeValue> newList = new ArrayList<>();
-            newList.add(values.get(0));
-            newList.add(values.get(values.size() - 1));
-            return newList;
-        }
-        return null;
-
-    }
 }