use standard datastore index or build my own
I'd suggest using pre-existing code and building around that in stead of re-inventing the wheel.
I am running a webapp on google appengine with python and my app lets users post topics and respond to them and the website is basically a collection of these posts categorized onto different pages.
Now I only have around 200 posts and 30 visitors a day right now but that is already taking up nearly 20% of my reads and 10% of my writes with the datastore.  I am wondering if it is more efficient to use the google app engine's built in get_by_id() function to retrieve posts by their IDs or if it is better to build my own.  For some of the queries I will simply have to use GQL or the built in query language because they are retrieved on more than just and ID but I wanted to see which was better.
Thanks!