What's the point of using Amazon SimpleDB?

Question

I thought that I could use SimpleDB to take care of the most challenging area of my application (as far as scaling goes) - twitter-like comments, but with location on top - till

Answer 1

I have about 50GB in SimpleDB, sharded across 30 domains. I use this to allow multiple keys on objects stored in S3, and also to reduce my S3 costs. I haven't played with using SimpleDB for full-text search, but I would not attempt it.

SimpleDB works, it's easy, and so on, but it isn't the right set of features for every situation. In your case, if you need aggregation, SimpleDB is not the right solution. It is built around the school of thought that the DB is just a key value store, and aggregation should be handled by an aggregation process that writes the results back to the key value store. This is exactly what is needed for some applications.

Here is a description of how I pinch pennies using SimpleDB