HADOOP-2240 Truncate for hbase

git-svn-id: https://svn.apache.org/repos/asf/lucene/hadoop/trunk@609256 13f79535-47bb-0310-9956-ffa450edef68

src/contrib/hbase/src/java/org/apache/hadoop/hbase/shell/TruncateCommand.java

@@ -0,0 +1,86 @@
+/**
+ * Copyright 2007 The Apache Software Foundation
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.shell;
+
+import java.io.IOException;
+import java.io.Writer;
+
+import org.apache.hadoop.hbase.HBaseAdmin;
+import org.apache.hadoop.hbase.HBaseConfiguration;
+import org.apache.hadoop.hbase.HColumnDescriptor;
+import org.apache.hadoop.hbase.HConnection;
+import org.apache.hadoop.hbase.HConnectionManager;
+import org.apache.hadoop.hbase.HTableDescriptor;
+import org.apache.hadoop.io.Text;
+
+/**
+ * Truncate table is used to clean all data from a table.
+ */
+public class TruncateCommand extends BasicCommand {
+  private Text tableName;
+
+  public TruncateCommand(Writer o) {
+    super(o);
+  }
+
+  public ReturnMsg execute(final HBaseConfiguration conf) {
+    if (this.tableName == null)
+      return new ReturnMsg(0, "Syntax error : Please check 'Truncate' syntax.");
+
+    try {
+      HConnection conn = HConnectionManager.getConnection(conf);
+      HBaseAdmin admin = new HBaseAdmin(conf);
+
+      if (!conn.tableExists(this.tableName)) {
+        return new ReturnMsg(0, "Table not found.");
+      }
+
+      HTableDescriptor[] tables = conn.listTables();
+      HColumnDescriptor[] columns = null;
+      for (int i = 0; i < tables.length; i++) {
+        if (tables[i].getName().equals(this.tableName)) {
+          columns = tables[i].getFamilies().values().toArray(
+              new HColumnDescriptor[] {});
+          break;
+        }
+      }
+      println("Truncating a '" + tableName + "' table ... Please wait.");
+
+      admin.deleteTable(tableName); // delete the table
+      HTableDescriptor tableDesc = new HTableDescriptor(tableName.toString());
+      for (int i = 0; i < columns.length; i++) {
+        tableDesc.addFamily(columns[i]);
+      }
+      admin.createTable(tableDesc); // re-create the table
+    } catch (IOException e) {
+      return new ReturnMsg(0, "error msg : " + e.toString());
+    }
+    return new ReturnMsg(0, "'" + tableName + "' is successfully truncated.");
+  }
+
+  public void setTableName(String tableName) {
+    this.tableName = new Text(tableName);
+  }
+
+  @Override
+  public CommandType getCommandType() {
+    return CommandType.DDL;
+  }
+}