# 修改HBase冷热分离数据表
#### 功能介绍
HBase通过org.apache.hadoop.hbase.client.Admin的modifyTable方法修改表信息。
#### 代码样例
- 取消冷热时间线。
  ```
  public void testModifyTable() {
    LOG.info("Entering testModifyTable.");
    // Specify the column family name.
    byte[] familyName = Bytes.toBytes("info");
    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);
        //Disable hot and cold separation.
        hcd .setValue(HColumnDescriptor.COLD_BOUNDARY, null);
        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\[1\] 只有在调用disableTable接口后， 再调用modifyTable接口才能将表修改成功。再请调用enableTable接口重新启用表。
  ![](https://support.huaweicloud.com/devg-cloudtable/public_sys-resources/note_3.0-zh-cn.png)
  注\[1\] 指的是代码样例中的"admin.modifyTable(tableName, htd); //注\[1\]"。
  
 
- 设置已有表的冷热分离功能。
  ```
  public void testModifyTable() {
    LOG.info("Entering testModifyTable.");
    // Specify the column family name.
    byte[] familyName = Bytes.toBytes("info");
    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);
        //Set the hot and cold separation function for an existing table.
        hcd .setValue(HColumnDescriptor.COLD_BOUNDARY, "86400"); 
        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\[1\] 只有在调用disableTable接口后， 再调用modifyTable接口才能将表修改成功。再请调用enableTable接口重新启用表。
  ![](https://support.huaweicloud.com/devg-cloudtable/public_sys-resources/note_3.0-zh-cn.png)
  注\[1\]指的是代码样例中的"admin.modifyTable(tableName, htd); //注\[1\]"。