title: Why would spark insertInto not write parquet files with a .parquet extension?
body: <p>I have a tool written in Scala that uses Spark's Dataframes API to write data to HDFS. This is the line that writes the data:</p>
  
  <pre class="lang-scala prettyprint-override"><code>temp_table.write.mode(SaveMode.Overwrite).insertInto(tableName)
  </code></pre>
  
  <p>One of our internal teams is using the tool on their hadoop/spark cluster and when it writes files to HDFS it is doing so without a .parquet extension on the files which (for reasons I won't go into) creates downstream problems for them.</p>
  
  <p>Here is a screenshot provided by that team which shows those files that don't have the .parquet extension:</p>
  
  <p><a href="https://i.stack.imgur.com/TTxwg.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/TTxwg.png" alt="enter image description here"></a></p>
  
  <p>Note that we have verified that they ARE parquet files (i.e. they can be read using <code>spark.read.parquet(filename)</code>)</p>
  
  <p>I have been unable to reproduce this problem in my test environment, when I run the same code there the files get written with a .parquet extension.</p>
  
  <p>Does anyone know what might cause parquet files to not be written with a .parquet extension?</p>