SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Function equals (children 1)
     ExpressionList (children 2)
      Function COUNT (children 1)
       ExpressionList
      Literal UInt64_1
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier test_index
   Function equals (children 1)
    ExpressionList (children 2)
     Function toUInt32 (children 1)
      ExpressionList (children 1)
       Identifier key_string
     Literal UInt64_1
