title: AWS Glue: crawler misinterprets timestamps as strings. GLUE ETL meant to convert strings to timestamps makes them NULL
body: <p>I have been playing around with <strong>AWS Glue</strong> for some quick analytics by following the tutorial 
  <a href="https://aws.amazon.com/blogs/big-data/build-a-data-lake-foundation-with-aws-glue-and-amazon-s3/" rel="noreferrer">here</a></p>
  
  <p>While I have been able to successfully create crawlers and discover data in Athena, I've had issues with the data types created by the crawler. The <code>date</code> and <code>timestamp</code> data types get read as <code>string</code> data types.</p>
  
  <p>I followed this up by creating an <code>ETL</code> job in GLUE using the data source created by the crawler as the input and a target table in <strong>Amazon S3</strong></p>
  
  <p>As part of the mapping transformation, I converted the data types of the date and timestamp as <code>string</code> to <code>timestamp</code> but unfortunately the ETL converted these column types to <code>NULLS</code>. I have contemplated using classifiers with <code>GROK</code> expressions but then decided transform them as part of ETL in GLUE. </p>
  
  <p>The timestamp format is as <code>1/08/2010  6:15:00 PM</code></p>