SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Subquery (alias time) (children 1)
     SelectWithUnionQuery (children 1)
      ExpressionList (children 1)
       SelectQuery (children 4)
        ExpressionList (children 2)
         Identifier event_time_microseconds
         Identifier event_time
        TablesInSelectQuery (children 1)
         TablesInSelectQueryElement (children 1)
          TableExpression (children 1)
           TableIdentifier system.metric_log
        ExpressionList (children 1)
         OrderByElement (children 1)
          Identifier event_time
        Literal UInt64_1
   ExpressionList (children 1)
    Function if (children 1)
     ExpressionList (children 3)
      Function equals (children 1)
       ExpressionList (children 2)
        Function dateDiff (children 1)
         ExpressionList (children 3)
          Literal \'second\'
          Function toDateTime (children 1)
           ExpressionList (children 1)
            Function tupleElement (children 1)
             ExpressionList (children 2)
              Identifier time
              Literal UInt64_1
          Function toDateTime (children 1)
           ExpressionList (children 1)
            Function tupleElement (children 1)
             ExpressionList (children 2)
              Identifier time
              Literal UInt64_2
        Literal UInt64_0
      Literal \'ok\'
      Function toString (children 1)
       ExpressionList (children 1)
        Identifier time