SET OPTIMIZATION LEVEL ---> runtime-options ---->

  runtime-options

  --+---> 'string-literal' ------+----->
    +---> parameter -------------+
    +---> parameter-marker ------+

  optimization-level=
  -+-> DEFAULT -----------------------+-->
   ++-+-> AGGRESSIVE SELECTIVITY --+--+
    | +-> FAST FIRST             --+  |
    | +-> SAMPLED SELECTIVITY  ----+  |
    | +-> TOTAL TIME   ------------+  |
    +-------------, <-----------------+