title: Calculate and control number of mappers used by Hive query
body: <p>I have a Hive table t1 which has 104 files. Out of the 104 files 1 file is 61 MB and remaining 103 files are less than 1 MB. When I execute the query</p>
  
  <pre><code>select count(*) from t1
  </code></pre>
  
  <p>29 mappers are executed along with 1 reducer. I'm trying to figure out why 29 mappers and how can reduce the number of mappers?</p>
  
  <pre><code>mapreduce.input.fileinputformat.split.maxsize=256MB
  mapreduce.input.fileinputformat.split.maxsize=1kb
  </code></pre>
  
  <p>Thanks</p>