cs, as described
     in <a class="xref" href="geqo.html" title="Chapter 62. Genetic Query Optimizer">Chapter 62</a>.  Otherwise the process is the same.
    </p><p>
     The finished plan tree consists of sequential or index scans of
     the base relations, plus nested-loop, merge, or hash join nodes as
     needed, plus any auxiliary steps needed, such as sort nodes or
     aggregate-function calculation nodes.  Most of these plan node
     types have the additional ability to do <em class="firstterm"