SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Function count (children 1)
     ExpressionList
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 2)
      TableIdentifier sample_prewhere
      SampleRatio 1 / 2
   Function equals (children 1)
    ExpressionList (children 2)
     Identifier CounterID
     Literal UInt64_1