title: What is the difference between --split-by and --boundary-query in SQOOP?
body: <p>Assuming we don't have a column where values are equally distributed, let's say we have a command like this:</p>
  <pre><code>sqoop import \
  ...
  --boundary-query &quot;SELECT min(id), max(id) from some_table&quot;
  --split-by id
  ...
  </code></pre>
  <p>What's the point of using <code>--boundary-query</code> here while -<code>-split-by</code> does the same thing?
  Is there any other way to use <code>--boundary-query</code>?
  Or any other way to split data more efficiently when there is no key(unique) column?</p>