title: Explain JOIN vs. LEFT JOIN and WHERE condition performance suggestion in more detail
body: <p>In <a href="https://stackoverflow.com/a/24875278/624998">this candidate answer</a> it is asserted that <code>JOIN</code> is better than <code>LEFT JOIN</code> under some circumstances involving some <code>WHERE</code> clauses because it does not confuse the query planner and is not "pointless". The assertion/assumption is that it should be obvious to anyone.</p>
  
  <p>Please explain further or provide link(s) for further reading.</p>