If you write your code in Java (or Ruby or Python or C++) it will come back and byte if you even need to scale or change architectures.

Actually, if you have to change architectures, you are probably bitten anyway.

If you need performance: 1. Do as much as you can in one SQL statement (unless you are using MySQL where the optimizer sucks) 2. If you can't do it in one SQL statement, use PL/SQL to do data processing as close as possible to the data - this will save on network load and PL/SQL is highly optimized to reduce overhead for embedded SQL statements.

With all the talk about "horizontal scalability" we sometimes forget the benefits of writing fast code in first place.