title: Hive,change table fileformat from orc to parquet is not supported?
body: <p>I have a hive table like this:</p>
  
  <pre><code>CREATE TABLE `abtestmsg_orc`(
    `eventname` string COMMENT 'AB测试方案上报事件：ABTest', 
    `eventtime` string COMMENT '事件上报时间', 
    `sessionid` string COMMENT 'Session标识', 
    `appkey` string COMMENT 'app标识', 
    `deviceid` string COMMENT 'device标识', 
    `content` string COMMENT 'AB测试方案的内容，格式是一个 json 字符串', 
    `item` array&lt;struct&lt;key:string,value:string&gt;&gt; COMMENT '扩展字段')
  PARTITIONED BY ( 
    `dt` string COMMENT '??')
  ROW FORMAT SERDE 
    'org.apache.hadoop.hive.ql.io.orc.OrcSerde' 
  STORED AS INPUTFORMAT 
    'org.apache.hadoop.hive.ql.io.orc.OrcInputFormat' 
  OUTPUTFORMAT 
    'org.apache.hadoop.hive.ql.io.orc.OrcOutputFormat'
  LOCATION
    'hdfs://hdfsmaster/hive/connector_transfer/abtestmsg_orc'
  </code></pre>
  
  <p>Now , I want to change the file format from ORC to parquet and change the location to other hdfs directory which contains the parquet files.So I at first I try to  change the format:</p>
  
  <pre><code>alter table abtestmsg_orc1 set fileformat parquet;
  </code></pre>
  
  <p>but it's a pitty that it throws an exception:</p>
  
  <p>FAILED: Execution Error, return code 1 from </p>
  
  <pre><code>org.apache.hadoop.hive.ql.exec.DDLTask. Changing file format (from ORC) is not supported for table connector_transfer.abtestmsg_orc1
  Error: Error while processing statement: FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. Changing file format (from ORC) is not supported for table connector_transfer.abtestmsg_orc1 (state=08S01,code=1)
  </code></pre>
  
  <p>I guess this exception means that when I change the fileformat , not only does hive change the table metadata, but also try to change all the data format from orc to parquet.But from the official doc , it says:</p>
  
  <pre><code>ALTER TABLE table_name [PARTITION partition_spec] SET FILEFORMAT file_format;
  
  **This statement changes the table's (or partition's) file format. For available file_format options, see the section above on CREATE TABLE. The operation only changes the table metadata. Any conversion of existing data must be done outside of Hive.**
  </code></pre>
  
  <p>But what I want to achive is to make its location to a parquet directory.</p>
  
  <p>So , what can I do to achive this ?</p>