title: Impala - convert existing table to parquet format
body: <p>I have a table that has partitions and I use avro files or text files to create and insert into a table.</p>
  
  <p>Once the table is done, is there a way to convert into parquet.
  I mean I know we could have done say <code>CREATE TABLE default.test( name_id STRING) 
  PARTITIONED BY ( year INT, month INT, day INT ) STORED AS PARQUET</code> initially while creating the table itself.<br>
  In my use case I 'll have to use textfiles initially. This is because I want to avoid creating multiple files inside of partition folders everytime I insert or update.  My table has a very high number of inserts and updates and this is creating a drop in performance. 
  Is there a way I could convert into parquet after the table is created and data inserted?</p>