Addresses #596

Added extra questions.

git-svn-id: file:///svn/tokudb@3501 c7de825b-a66e-492c-adef-691d508d4ae1

order-maintenance/om.h

@@ -36,6 +36,34 @@ struct OMS {
         6-  Do we need some way of 'loading' an order maintenance structure?
             i.e. use these tags for the following items instead of 'inserting' over and over.
         7-  The tag might not be able to be just 64 bits, is it ok to use 2 64 bit ints?
+       
+       
+        What we don't understand:
+        *   A separate order maintenance structure for each node, or for each leaf? (Emailed)
+        *   >When we insert a key-value pair into a BRT leaf, we need to log enough information to rebuild the leaf after a crash.
+            >And at the time of recovery, we don't have a comparison function.
+            What is involved in rebuilding a node?
+                Our guess is that the only thing necessary is:
+                    1-Recreate _which_ elements were stored in it.
+                    2-Recreate the _order_ of the elements stored in it.
+                Is there anything else?
+                If that's it, it explains why we don't need an OMS for each node (just for each leaf).
+                Nodes only require #1, and when the elements are recreated the order doesn't matter (and can even change).
+            Is our guess correct?
+        *   forwards backwards idea?
+        *   
+        
+        1-  What does the PMA hold?  Does it hold pointers to DBTs, or it actually holds
+            the DBTs and their data in-line?
+        2-  What is being logged, and why is it being logged that way?
+            Do we just store old and new slots in the PMA?
+            If so, what does that actually give us?
+            Do we just serialize to disk by storing things in order?
+        3-  Logging:  Do we really need to log ALL changes to tags,
+            or only enough to 'reconstruct' the OMS such that we have a comparison function?
+            First case gives us O(log n), second makes O(1) possible.
+            (First case may be possible with O(1) but we'd have to devise a new algorithm)
+        
 */
 
 template <typename ITEM_TYPE, typename EXTRA_RENUMBER, typename EXTRA_CMP>