Hello,
The viewers working with a data source display the source and cannot restrict it. You can use a special transformation where it check the index and displays nothing if it does not meet a condition. Then you can use 3 viewer web parts with one data source and different transformations.
Otherwise I would recommend you to use 3 stand-alone web parts and set up a cache properly to restrict the database calls. You can use a Where condition for the second and third repeater like for example:
DocumentID NOT IN (Select TOP 3 DocumentID FROM ... )
More information about cache can be found here:
Caching options and at Martin Hejtmanek's
blog.
Best regards,
Helena Grulichova