Thanks for suggestion. I did try but without success.
1. took Product of the whole datatable instances
2. within database, drop all records from teh datatable
3. added pzpvstream column to the datatable
4. import Product from step 1. - failed with error:
Cannot save instance of class XXXXXXX; it belongs to fully exposed table pegadata.xxxxx in database PegaDATA, but the instance has properties which do not correspond to columns: pxMoveImportOperName , pxMoveImportOperId , pxMoveImportDateTime
Looks like import in same structure could not help here, what i tried long back was have a utility/data page with all the data from Data Table(we generally have one at page and page list level). Keep this data page populated and now 2 options :
1. Use existing table/db structure just remove all the columns from table which you want to be in blob and remove the mapping from class rule as well. Add new column pzpvstream as Blob type, test the connection from class and commit the changes in db. Now using the utility to an obj-save with commit in save class.
2. Create new table/db structure with needed column + pzpvstream column change ur sysadmin-db-table for class test connection from class and use have utility to do obj-save + commit