I started developing an app using the Cloud SQL database because I found it easier to understand than the Datastore option (I’d done lots of SQL before). After the first month’s billing of the Cloud SQL I see that it isn’t cheap, barely any queries were done and the price was already higher than I expected.
The app is a game which causes many small requests to the server per minute, no huge queries are needed, just little ones to download game status and accounts.
Would moving over to the GAE Datastore be worthwhile in terms of cost? (I’ve read the billing pages, but it’s hard to get a feel for how much the difference in cost would be without having actually tried it)
Its very hard to derminae if a system move from CloudSQL to datastore will save money, you should really understand why CloudSQL cost more then you expected and try to estimate how much it will cost on the datastore. There are optimizations then can be done for using the datastore which aren’t relevant in CloudSQL, but mostly I think that you need to check how to lower the query rate (like for example using memcache), this will save you a lot of money.