To determine the number of reducers in Hive "order by" clause
<p>I have a 2.6 MB sized CSV file. I created a hive table and loaded the csv file in it.</p>

<p>Now, if I write a query as "select * from abc order by a;" , mapreduce used 1 reducer. How did it identify the number of reducer as 1? Did it use the default value "1" or something else?</p>

<p>In general, how does hive decide how many reducers to use in an "order by", "sort by" or "group by" clause?</p>