title: Right_only Merging two data frames. What does it return?
body: <p>I have merged two data frames from two large data tables (300k + rows) but when I right_only merged them on various columns, only six rows returned for one merged table, and sometimes the merge returned a table with zero rows. Can someone help me understand what is happening?</p>
  
  <p>Here is an example of the command I used to merge:</p>
  
  <pre><code>right_retail = merged_retail[merged_retail['_merge']=='right_only']
  </code></pre>
  
  <p>Regards </p>