A quote that combines the rules about optimization with the rules about data structures: "NoSQL databases that only have weak consistency are enforcing a broadly applied premature optimization on the entire system." --- Alexander Lloyd, Google

Also in support of Rule 5, see Eric Raymond's treatment of Data-Driven Programming:

"Even the simplest procedural logic is hard for humans to verify, but quite complex data structures are fairly easy to model and reason about. To see this, compare the expressiveness and explanatory power of a diagram of (say) a fifty-node pointer tree with a flowchart of a fifty-line program. Or, compare an array initializer expressing a conversion table with an equivalent switch statement. The difference in transparency and clarity is dramatic. See Rob Pike's Rule 5.

"Data is more tractable than program logic. It follows that where you see a choice between complexity in data structures and complexity in code, choose the former. More: in evolving a design, you should actively seek ways to shift complexity from code to data."

http://www.catb.org/~esr/writings/taoup/html/ch01s06.html#id...

http://www.catb.org/~esr/writings/taoup/html/generationchapt...