SELECT toStartOfDaytoDateTimeDs AS datetime_day_Ds AppIdentifier AS AppIdentifier -- sumMergedViewCount AS index_mergedviewcount_0 GREATEST countDISTINCT ViewContent2 maxCASTMergedViewCount A

根据错误消息，问题出在无法找到一个适用于Int64和UInt64的通用类型。您可以尝试使用CAST函数将MergedViewCount转换为Int64类型，以便与count(DISTINCT ViewContent2)的结果进行比较。修改后的查询如下所示：

SELECT toStartOfDay(toDateTime(Ds)) AS datetime_day_Ds, AppIdentifier AS AppIdentifier, GREATEST( count(DISTINCT ViewContent2), max(CAST(MergedViewCount AS Int64)) ) AS index_mergedviewcount_0 FROM your_table GROUP BY datetime_day_Ds, AppIdentifier;

请将"your_table"替换为您实际的表名。这样修改后，您应该能够成功执行查询。