title: Convert Blank to NULL in Hive
body: <p>I am trying to convert blank values in the source file to NULL in the hive table by setting the property <code>'serialization.null.format' = ''</code> . The query I have written in hive is:</p>
  
  <pre><code>create table test(a int, b string) stored as parquet TBLPROPERTIES('serialization.null.format'='');
  </code></pre>
  
  <p>And then insert values into this through impala something like this:</p>
  
  <pre><code>insert overwrite table test values (1, ''), (2, 'b');
  </code></pre>
  
  <p>The result of this shows something like this:</p>
  
  <pre><code>| a | b |
  
  
  | 1 |   |
  
  | 2 | b |
  </code></pre>
  
  <p>Can someone help me out here as to why is the blank not getting converted to NULL ?</p>