title: Under what circumstances would likelihood() be useful?
body: <p>Reading through the sqlite documentation I found the following function:</p>
  
  <p><a href="http://www.sqlite.org/lang_corefunc.html#likelihood">http://www.sqlite.org/lang_corefunc.html#likelihood</a></p>
  
  <blockquote>
    <p>The likelihood(X,Y) function returns argument X unchanged. The value Y in likelihood(X,Y)
    must be a floating point constant between 0.0 and 1.0, inclusive. The likelihood(X) function
    is a no-op that the code generator optimizes away so that it consumes no CPU cycles during
    run-time (that is, during calls to sqlite3_step()). The purpose of the likelihood(X,Y)
    function is to provide a hint to the query planner that the argument X is a boolean that is
    true with a probability of approximately Y. The unlikely(X) function is short-hand for
    likelihood(X,0.0625). </p>
  </blockquote>
  
  <p>Assuming that i know that 1 will return 75% of the time, how would:</p>
  
  <pre><code>select likelihood(x,.75) 
  </code></pre>
  
  <p>help the query optimizer?</p>