SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Function equals (children 1)
     ExpressionList (children 2)
      Literal UInt64_1
      Function position (children 1)
       ExpressionList (children 2)
        Literal \'abcdefgh\'
        Function materialize (children 1)
         ExpressionList (children 1)
          Literal \'a\'
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier system.numbers
   Literal UInt64_129