Save content of Spark DataFrame as a single CSV file : <p>Say I have a Spark DataFrame which I want to save as CSV file. After <strong>Spark 2.0.0</strong> , <strong>DataFrameWriter</strong> class directly supports saving it as a CSV file.</p>

<p>The default behavior is to save the output in multiple <strong>part-*.csv</strong> files inside the path provided. </p>

<p>How would I save a DF with :</p>

<ol>
<li>Path mapping to the exact file name instead of folder</li>
<li>Header available in first line</li>
<li>Save as a single file instead of multiple files.</li>
</ol>

<p>One way to deal with it, is to coalesce the DF and then save the file. </p>

<pre><code>df.coalesce(1).write.option("header", "true").csv("sample_file.csv")
</code></pre>

<p>However this has disadvantage in collecting it on Master machine and needs to have a master with enough memory. </p>

<p>Is it possible to write a single CSV file without using <strong>coalesce</strong> ? If not, is there a efficient way than the above code ?</p>
