Find a bug of Tableau 10 Desktop today.
If the data source is Excel, and a column of date is in custom type, like below in Chinese which means yyyy"Year"mm"Month“dd"Date“. (This is by tableau when copy the crosstab)
Then, if you save the Tableau work book as twbx, and then extract the data source, and change the field type from number to date, then the date will be added 2 days up.
However, if you extract the data before save as twbx then is problem won't occur.
The demo data source and tableau workbook are attached.
Here is how to reproduce the bug:
1. use Excel file as the data source.
2. save the workbook as twbx, and use Extract as Connection.
3. change the data type from # to date, and then convert it to Discrete
4. drag the pill to Rows, and find the first date which should be 2016-11-1 is changed to 2016-11-3
PS. Someone may ask why I use a custom type of date in Excel. Well this excel is a mid-data-source which I made by Tableau. I used tableau processed some big tables and worked out a new table and exported it as a new smaller data source. So it was tableau who made that custom date type for the "Workbook"-"Copy"-"Crosstab“.