ver extremely difficult to
   create, it would probably be too slow to be of any real use.)
   The system can recognize simple inequality implications, for example
   <span class="quote">“<span class="quote">x &lt; 1</span>”</span> implies <span class="quote">“<span class="quote">x &lt; 2</span>”</span>; otherwise
   the predicate condition must exactly match part of the query's
   <code class="literal">WHERE</code> condition
   or the index will not be recognized as usable. Matching takes
   place 