Difference between obj and RDB methods

1. What is the advantage of Obj- methods over RDB methods?

Using any of the Obj- operations allows you to take advantage of transactions (deferred database transactions) whereas RDB- operations execute immediately.

When using Obj-Save and Obj-Delete, you can cancel or rollback all of the related operations without committing the changes to the database. RDB- operations commit immediately.

Obj- methods can be used to retrieve data from the BLOB (pzpvstream column) and save data to the BLOB. So they can be used for properties that are not exposed along with the exposed properties.

RDB- methods cannot read from or update the BLOB.

So if our table has the pzpvstream (BLOB) column then we should always use Obj- methods. This will work on the exposed columns as well as the BLOB.

2.      When Obj-Open can access external database well, what is the necessity of RDB-Open? (Or when exactly we go for RDB methods or what is the advantage of RDB- methods over Obj- methods?)

o   RDB methods support stored procedures. OBJ methods do not.

o   RDB method support hand-crafted / optimized SQL. OBJ methods generate all SQL on the fly behind the scenes.

o   OBJ methods support a PRPC unit of work / two phase commit. RDB methods are atomic - they are unique transactions and automatically commit on completion.

o   Most Cases you do NOT have to map tables to PRPC objects to use RDB methods. RDB methods only see / touch those columns that are in your DB Schema, and you don't even have to map them to objects / properties . On the other side; mapping a table to a PRPC 'external' class and using obj- methods directly extends PRPC object model to the external table.