SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Identifier metric
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier system.metrics
   Function less (children 1)
    ExpressionList (children 2)
     Function length (children 1)
      ExpressionList (children 1)
       Identifier description
     Literal UInt64_10
