You could store the historical data into a QVD each month and just load data for the current month from your source system.
That would satisfy your requirements.
If you can provide an example of your app, I could suggest the proper adjustment of the script or you could just search for STORE QVD for more information on storing tables as QVD's in your script.
With kind regards,
Thank you for the response.
I understand what you mean, so now when I store the historical data into a new QVD, in the bar chart I use Month as my dimension and 3 expressions as 3 bars. so how do I handle the case where I need historical data for previous months and current data for current month, all in 1 chart?
By example this is what you should be doing to retain the data
in Jan >> Create a QVD say 2017archive.QVD
in Feb >> Load data only for FEB from source system and concatenate with 2017archive.QVD and overwrite 2017archive.QVD
in Mar >> Load data only for March from source system and concatenate with 2017archive.QVD 2017archive.QVD
and the process continues!