title: How do I run md5() on a bigint in Presto?
body: <pre><code>select md5(15)
  </code></pre>
  
  <p>returns</p>
  
  <pre><code>Query failed (#20160818_193909_00287_8zejd): line 1:8:
   Unexpected parameters (bigint) for function md5. Expected: md5(varbinary)
  </code></pre>
  
  <p>How do I hash 15 and get back a string? I'd like to select 1 in 16 items at random, e.g. <code>where md5(id) like '%3'</code>.</p>
  
  <p>FYI I might be on version 0.147, don't know how to tell.
  FYI I found <a href="https://github.com/prestodb/presto/pull/2397" rel="noreferrer">this PR</a>.  md5 would be cross-platform, which is nice, but I'd take a Presto-dependent hash function that spread ids relatively uniformly. I suppose I could implement my own linear formula. Seems awkward.</p>