Data Dep't here. Postgres scales great on Heroku, AWS, and in general. We've got users doing many thousands of query per second, and terabytes of data. Not a pr

Data Dep't here. Postgres scales great on Heroku, AWS, and in general. We've got users doing many thousands of query per second, and terabytes of data. Not a problem. The issue with the number of connections is that each connection creates a process on the server. We cap the connections at 500, because at that point you start to see problems with O(n^2) data structures in the Postgres internals that start to make all kinds of mischief. This has been improved over the last few releases, but in general, it's still a good idea to try and keep the number of concurrent connections down. *EDIT: thanks. not a thread. :)