title: Bug or new behavior in BigQuery?
body: <p>Since two days ago (August 10th 2016), a query which used to work (using tables of the BQ Export for Google Analytics Premium) has stopped working. It returns the following error: </p>
  
  <blockquote>
    <p>Error: Cannot union tables : Incompatible types.
    'hits.latencyTracking.userTimingVariable' : TYPE_INT64
    'hits.latencyTracking.userTimingVariable' : TYPE_STRING</p>
  </blockquote>
  
  <p>After some investigation, it seems to be a problem with using IN in a WHERE clause when I query tables from before and after August 10th (table <em>ga_sessions_20160810</em>). </p>
  
  <p>I've simplified my original query to provide a dummy one which has the same basic structure. The following query works (querying data from 2016-08-08 and 2016-08-09): </p>
  
  <pre><code>SELECT fullVisitorId, sum(totals.visits)
  FROM (select * from TABLE_DATE_RANGE([XXXXXXXX.ga_sessions_],TIMESTAMP('2016-08-08'),TIMESTAMP('2016-08-09')))
  WHERE fullVisitorId in(
      SELECT fullVisitorId
      FROM TABLE_DATE_RANGE([XXXXXXXX.ga_sessions_],TIMESTAMP('2016-08-08'),TIMESTAMP('2016-08-09'))
  )
  GROUP BY fullVisitorId
  </code></pre>
  
  <p>But this other one (just changing dates, in this case from 2016-08-09 and 2016-08-10) returns the error:</p>
  
  <pre><code>SELECT fullVisitorId, sum(totals.visits)
  FROM (select * from TABLE_DATE_RANGE([XXXXXXXX.ga_sessions_],TIMESTAMP('2016-08-09'),TIMESTAMP('2016-08-10')))
  WHERE fullVisitorId in(
      SELECT fullVisitorId
      FROM TABLE_DATE_RANGE([XXXXXXXX.ga_sessions_],TIMESTAMP('2016-08-09'),TIMESTAMP('2016-08-10'))
  )
  GROUP BY fullVisitorId
  </code></pre>
  
  <p>This last query works fine either if I delete the WHERE clause or if I just try the query within the IN, so I guess the problem is with the structure WHERE <em>field</em> IN(...). Furthermore, querying only data from 2016-08-10 does work. Also, the same happens using a field different to fullVisitorId and running the same queries in different BQ projects.</p>
  
  <p>Looking to the error description, it should be a problem with variable types, but I don't know what is hits.latencyTracking.userTimingVariable. My query used to work properly, so I can't figure out what has changed that produces the error. Have some fields changed their type or what happened?</p>
  
  <p>Has anyone experienced this? Is this a bug or a new behavior in BigQuery? How can this error be solved? </p>