修改表

功能简介

HBase通过org.apache.hadoop.hbase.client.Admin的modifyTable方法修改表信息。

代码样例

public void testModifyTable() {
  LOG.info("Entering testModifyTable.");

  // Specify the column family name.
  byte[] familyName = Bytes.toBytes("education");
  Admin admin = null;
  try {
    // Instantiate an Admin object.
    admin = conn.getAdmin();
    // Obtain the table descriptor.
    HTableDescriptor htd = admin.getTableDescriptor(tableName);
    // Check whether the column family is specified before modification.
    if (!htd.hasFamily(familyName)) {
      // Create the column descriptor.
      HColumnDescriptor hcd = new HColumnDescriptor(familyName);
      htd.addFamily(hcd);
      // Disable the table to get the table offline before modifying
      // the table.
      admin.disableTable(tableName);
      // Submit a modifyTable request.
      admin.modifyTable(tableName, htd);  //注[1]
      // Enable the table to get the table online after modifying the
      // table.
      admin.enableTable(tableName);
    }
    LOG.info("Modify table successfully.");
  } catch (IOException e) {
    LOG.error("Modify table failed " ,e);
  } finally {
    if (admin != null) {
      try {
        // Close the Admin object.
        admin.close();
      } catch (IOException e) {
        LOG.error("Close admin failed " ,e);
      }
    }
  }
  LOG.info("Exiting testModifyTable.");
}

注意事项

注[1] 只有在调用disableTable接口后， 再调用modifyTable接口才能将表修改成功。之后，请调用enableTable接口重新启用表。