diff --git a/src/java/org/apache/sqoop/mapreduce/MergeMapperBase.java b/src/java/org/apache/sqoop/mapreduce/MergeMapperBase.java
index 378a12e0..1bb8deef 100644
--- a/src/java/org/apache/sqoop/mapreduce/MergeMapperBase.java
+++ b/src/java/org/apache/sqoop/mapreduce/MergeMapperBase.java
@@ -76,9 +76,10 @@ protected void processRecord(SqoopRecord r, Context c)
     }
     Object keyObj = null;
     if (keyColName.contains(",")) {
+        String connectStr = new String(new byte[]{1});
         StringBuilder keyFieldsSb = new StringBuilder();
         for (String str : keyColName.split(",")) {
-            keyFieldsSb.append("+").append(fieldMap.get(str).toString());
+            keyFieldsSb.append(connectStr).append(fieldMap.get(str).toString());
         }
         keyObj = keyFieldsSb;
     } else {