t = select * from tb where isDuplicated([ datetime, symbol ], FIRST) == 1 => The where clause [isDuplicated([ datetime, symbol ], FIRST) == 1] of a distributed/partitioned sql shouldn't use any aggregate or order-sensitive function.
后面加个map。在where子句中使用结果与数据的行次序有关的函数如 isDuplicated ，first，firstNot 等，如果涉及到多个分区，必须使用map关键字，以在每个分区内单独执行where条件。
