title: How can I read each Parquet row group into a separate partition?
body: <p>I have a parquet file with 10 row groups:</p>
  
  <pre class="lang-py prettyprint-override"><code>In [30]: print(pyarrow.parquet.ParquetFile("/tmp/test2.parquet").num_row_groups)
  10
  </code></pre>
  
  <p>But when I load it using Dask Dataframe, it is read into a single partition:</p>
  
  <pre class="lang-py prettyprint-override"><code>In [31]: print(dask.dataframe.read_parquet("/tmp/test2.parquet").npartitions)
  1
  </code></pre>
  
  <p>This appears to contradict <a href="https://stackoverflow.com/a/58464198/974555">this answer</a>, which states that <em>Dask Dataframe reads each Parquet row group into a separate partition.</em></p>
  
  <p>How can I read each Parquet row group into a separate partition with Dask Dataframe?  Or must the data be distributed over different files for this to work?</p>