Updated Filer Redis Setup (markdown)

Filer-Redis-Setup.md

@@ -17,15 +17,13 @@ This is where `redis3` can help. The internal data structure is:
 
 ```
  <directory_path>: <skip list>
- <skip list item 1>: <sorted set>
- <skip list item 2>: <sorted set>
+ <skip list item 1>: <sorted set of 1 million names>
+ <skip list item 2>: <sorted set of 1 million names>
  ...
 ```
-The directory list is stored as a skip list, and the child names are spread into the list items.
-
-This prevents each directory entry from being too large and slower to access.
+The directory list is stored as a skip list, and the child names are spread into the list items. This prevents each directory entry from being too large and slower to access. Skip list has `O(log(N))` access time. With each sorted set storing 1 million names, it should scale very well to billions of files in one directory.
 
 Compared to `redis2`, there are extra cost to maintain this list:
 * Adding or deleting needs one additional lock operation.
-* Updating an entry needs to takes O(log(N)) times to access the skip list item first.
-So no need to jump to `redis3` in a hurry.
+* Updating an entry needs to takes `O(log(N))` times to access the skip list item first.
+So no need to jump to `redis3` in a hurry unless you have to.