title: What's the point of using Amazon SimpleDB?
body: <p>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 the point when I sat down to actually start implementing it with SDB.</p>
  
  <p>First thing, SDB has a 1000 bytes limitation per attribute value, which is not enough even for comments (probably need to break down longer values into multiple attributes). </p>
  
  <p>Then, maximum domain size is 10GB. The promise was that you could scale up without worrying about database sharding etc., since SDB will not degrade with increasing loads of data. But if I understand correctly, with domains I would have exactly the same problem as with sharding, ie. at some point need to implement data records' distribution and queries across domains on application level.</p>
  
  <p>Even for the simplest objects that I have in the whole application, ie. atomic user ratings, SDB is not an option, because it cannot calculate an average within the query (everything is string based). So to calculate average user rating for an object, I would have to load all records - 250 at a time - and calculate it on application level.</p>
  
  <p>Am I missing something about SDB? Is 10GB really that much of a database to get over all SDB limitations? I was honestly enthusiastic about taking advantage of SDB, since I use S3 and EC2 already, but now I simply don't see a use case.</p>