@Jayasreed - when Obj-Open operations are performed all the data available in blob will be dumped on the Page where it needs to copy. If you want to read the data from the columns which are exposed then write the Report Definition to retrieve the data for the exposed columns.

@Jayasreed

Whenever you want to open any particular instance stored in internal or external DB using a key or Handle then you can use this methods: Obj-Open and Obj-Open-By-Handle

And this method opens the instance on the steppage mentioned which will include exposed columns as well as unexposed properties (like px and py OOTB properties)

So if you check the query in tracer, it will refer to pzPVStream but it will fetch both type of properties.

Similarly in Obj-Browse as well you can include both exposed and unexposed properties but in where clause you can only select exposed properties.

Hope I answered your query!