code: private static boolean isUsefulPartitioningExpression(AbstractExpression expr) {
          if (expr instanceof ParameterValueExpression) {
              return true;
          }
          if (expr instanceof ConstantValueExpression) {
              return true;
          }
  
          return false;
      }
docs: Returns true if the expression can be used to restrict plan execution to a single partition.
  For now this is anything other than a constant or parameter.  (In the future, one could
  imagine evaluating expressions like sqrt(8 * 8) and the like during planning)
  
  @param expr  The expression to consider
  @return      true or false