redshift datediff not working when current_timestamp is used but working when getdate() function is used
<p>I am querying a timestamp column with datediff from <strong>current_timestamp</strong>. But it gives error.</p>

<pre><code>DATEDIFF(minute, timestamp_field ,current_timestamp::TIMESTAMP) 
or 
DATEDIFF(minute, timestamp_field ,current_timestamp)
DataType of timestamp_field is "TIMESTAMP DEFAULT '2016-03-29 20:33:33.404256'::timestamp without time zone"
</code></pre>

<p><strong>OutPut:</strong> </p>

<blockquote>
  <p>ERROR: Specified types or functions (one per INFO message) not
  supported on Redshift tables.</p>
  
  <p>Warnings: Function ""timestamp"(timestamp with time zone)" not
  supported. Function "timestamptz(timestamp with time zone,integer)"
  not supported. Function "timestamptz(text)" not supported.</p>
</blockquote>

<p>But following query is working if I use <strong>getdate()</strong> function</p>

<pre><code>DATEDIFF(minute, timestamp_field ,getdate()::TIMESTAMP)
</code></pre>