/code>, <code class="literal">random</code>,
       <code class="literal">system</code>, <code class="literal">bernoulli</code>
       and <code class="literal">auto</code>. <code class="literal">off</code> disables remote
       sampling, so all data are transferred and sampled locally.
       <code class="literal">random</code> performs remote sampling using the
       <code class="literal">random()</code> function to choose returned rows,
       while <code class="literal">system</code> and <code class="