Explain EXPLAIN SYNTAX (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 4)
    ExpressionList (children 2)
     Function max (children 1)
      ExpressionList (children 1)
       Identifier x1
     Identifier x2
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier test
    ExpressionList (children 1)
     Literal Int64_-1
    ExpressionList (children 2)
     OrderByElement (children 1)
      Literal Int64_-2
     OrderByElement (children 1)
      Literal Int64_-1
