SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 2)
    Asterisk
    Function length (alias l) (children 1)
     ExpressionList (children 1)
      Identifier arr
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier prewhere_column_missing
   Function equals (children 1)
    ExpressionList (children 2)
     Identifier l
     Literal UInt64_0