MAPREDUCE-6246. DBOutputFormat.java appending extra semicolon to query which is incompatible with DB2. Contributed by ramtin and Gergely Novák.

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/db/DBOutputFormat.java

@@ -20,6 +20,7 @@ package org.apache.hadoop.mapreduce.lib.db;
 
 import java.io.IOException;
 import java.sql.Connection;
+import java.sql.DatabaseMetaData;
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
 
@@ -51,6 +52,8 @@ public class DBOutputFormat<K  extends DBWritable, V>
 extends OutputFormat<K,V> {
 
   private static final Log LOG = LogFactory.getLog(DBOutputFormat.class);
+  public String dbProductName = "DEFAULT";
+
   public void checkOutputSpecs(JobContext context) 
       throws IOException, InterruptedException {}
 
@@ -158,7 +161,12 @@ extends OutputFormat<K,V> {
         query.append(",");
       }
     }
-    query.append(");");
+
+    if (dbProductName.startsWith("DB2") || dbProductName.startsWith("ORACLE")) {
+      query.append(")");
+    } else {
+      query.append(");");
+    }
 
     return query.toString();
   }
@@ -177,7 +185,10 @@ extends OutputFormat<K,V> {
     try {
       Connection connection = dbConf.getConnection();
       PreparedStatement statement = null;
-  
+
+      DatabaseMetaData dbMeta = connection.getMetaData();
+      this.dbProductName = dbMeta.getDatabaseProductName().toUpperCase();
+
       statement = connection.prepareStatement(
                     constructQuery(tableName, fieldNames));
       return new DBRecordWriter(connection, statement);

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-jobclient/src/test/java/org/apache/hadoop/mapreduce/lib/db/TestDBOutputFormat.java

@@ -18,7 +18,9 @@
 package org.apache.hadoop.mapreduce.lib.db;
 
 import java.io.IOException;
+import java.lang.reflect.Field;
 
+import org.apache.commons.lang.StringUtils;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.io.NullWritable;
 import org.apache.hadoop.mapreduce.Job;
@@ -26,6 +28,7 @@ import org.junit.Test;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.fail;
 
 public class TestDBOutputFormat {
   private String[] fieldNames = new String[] { "id", "name", "value" };
@@ -46,6 +49,48 @@ public class TestDBOutputFormat {
     assertEquals(nullExpected, actual);
   }
 
+  @Test
+  public void testDB2ConstructQuery() {
+    String db2expected = StringUtils.removeEnd(expected, ";");
+    String db2nullExpected = StringUtils.removeEnd(nullExpected, ";");
+
+    try {
+      Class<?> clazz = this.format.getClass();
+      Field field = clazz.getDeclaredField("dbProductName");
+      field.setAccessible(true);
+      field.set(format, "DB2");
+    } catch (IllegalAccessException | NoSuchFieldException e) {
+      fail(e.getMessage());
+    }
+
+    String actual = format.constructQuery("hadoop_output", fieldNames);
+    assertEquals(db2expected, actual);
+
+    actual = format.constructQuery("hadoop_output", nullFieldNames);
+    assertEquals(db2nullExpected, actual);
+  }
+
+  @Test
+  public void testORACLEConstructQuery() {
+    String oracleExpected = StringUtils.removeEnd(expected, ";");
+    String oracleNullExpected = StringUtils.removeEnd(nullExpected, ";");
+
+    try {
+      Class<?> clazz = this.format.getClass();
+      Field field = clazz.getDeclaredField("dbProductName");
+      field.setAccessible(true);
+      field.set(format, "ORACLE");
+    } catch (IllegalAccessException | NoSuchFieldException e) {
+      fail(e.getMessage());
+    }
+
+    String actual = format.constructQuery("hadoop_output", fieldNames);
+    assertEquals(oracleExpected, actual);
+
+    actual = format.constructQuery("hadoop_output", nullFieldNames);
+    assertEquals(oracleNullExpected, actual);
+  }
+
   @Test
   public void testSetOutput() throws IOException {
     Job job = Job.getInstance(new Configuration());