title: Cannot use NEGATIVE function on Float8 data type. What gives?
body: <p>I am using the following:</p>
  
  <pre><code>Apache Drill 1.5.0
  
  Distributor ID: Ubuntu
  Description:    Ubuntu 14.04.3 LTS
  Release:    14.04
  Codename:   trusty
  
  
  java version "1.8.0_60"
  Java(TM) SE Runtime Environment (build 1.8.0_60-b27)
  Java HotSpot(TM) 64-Bit Server VM (build 25.60-b23, mixed mode)
  </code></pre>
  
  <p>When I run the following query</p>
  
  <pre><code>SELECT NEGATIVE(`EX QTY`) as `quantity`, `contract_symbol`, `contract_expiration_month` FROM dfs.`BobBrokerJapanFutures.json` WHERE  `B/S` = 'S'
  </code></pre>
  
  <p>I get an error saying </p>
  
  <pre><code>Query Failed: An Error Occurred
  org.apache.drill.common.exceptions.UserRemoteException: SYSTEM ERROR: SchemaChangeException: Failure while trying to materialize incoming schema. Errors: Error in expression at index -1. Error: Missing function implementation: [negative(FLOAT8-OPTIONAL)]. Full expression: --UNKNOWN EXPRESSION--.. Fragment 0:0 [Error Id: 0d38ceb9-c490-442b-87da-a22043093abd on vagrant-ubuntu-trusty-64:31010
  </code></pre>
  
  <p>This means I am not supposed to use negative on Float8, right?</p>
  
  <p>But then when I used the same query but with ABS function, it worked perfectly.</p>
  
  <p>What's going on?</p>