Add some notes

immutable_tree.go

@@ -145,10 +145,19 @@ func (t *ImmutableTree) Export() *Exporter {
 // Get returns the index and value of the specified key if it exists, or nil and the next index
 // otherwise. The returned value must not be modified, since it may point to data stored within
 // IAVL.
+// TODO: Understand what is this index? Index on its own isn't well defined
+// index across all leaves?
 func (t *ImmutableTree) Get(key []byte) (index int64, value []byte) {
 	if t.root == nil {
 		return 0, nil
 	}
+	// IMPLEMENT FOLLOWING PSUEDOCODE
+	// value, version := t.nodeDb.fastGet(key)
+	// if value == nil { return t.root.get(t, key)}
+	// if version > t.version { return t.root.get(t, key)}
+	// else: return value
+	// TODO: Figure out what index is
+
 	return t.root.get(t, key)
 }
 

nodedb.go

@@ -34,8 +34,12 @@ var (
 	// and <first-version> = version O was created at.
 	orphanKeyFormat = NewKeyFormat('o', int64Size, int64Size, hashSize) // o<last-version><first-version><hash>
 
-	//
-	fastKeyFormat = NewKeyFormat('f', 0) //
+	// Key Format for making reads and iterates go through a data-locality preserving db.
+	// The value at an entry will list what version it was written to.
+	// Then to query values, you first query state via this fast method.
+	// If its present, then check the tree version. If tree version >= result_version,
+	// return result_version. Else, go through old (slow) IAVL get method that walks through tree.
+	fastKeyFormat = NewKeyFormat('f', 0) // f<keystring>
 
 	// Root nodes are indexed separately by their version
 	rootKeyFormat = NewKeyFormat('r', int64Size) // r<version>