SortedDataInterface is similar to RecordStore, except SortedDataInterface is the interface through which to access WT tables for our index data and RecordStore is the interface though which to access the WT tables for our collection data. We do not store data in the same format in WT tables for index data as collection data.

We will open a cursor at a WT checkpoint. Read about that here http://source.wiredtiger.com/3.2.0/checkpoint.html.

WT has a WiredTigerCursor class responsible for creating the cursors that indexes use. WiredTigerCursor gets a cursor from the WiredTigerSessionCache. WiredTigerSessionCache is responsible for calling open_cursor against WT. It looks like the validate() function goes through here to here where we use the IndexAccessMethod to instantiate a cursor. WiredTigerCursor appears to open a cursor via one of two WiredTigerSessionCache functions to get cursors.