The summary.
SMART CONTRACT CODE IS FREQUENTLY UNCHANGEABLE AND DIRECTLY FINANCIAL
Which makes correctness matter more than in almost any other context. Update internal state before making external calls, use audited libraries, and never deploy code handling value without independent review.
The regulatory position varies and is changing — take advice.
LEARN SQL PROPERLY
Almost every application stores data, and inefficient queries are the commonest performance fault. Joins, aggregation, window functions, indexes, and reading query plans.
TREAT INFRASTRUCTURE AND CONFIGURATION FILES AS CODE
Version controlled, reviewed and tested. That is what makes infrastructure repeatable.
Be careful with formats that permit arbitrary object construction — some can execute code.
A DOMAIN LANGUAGE ACQUIRING CONDITIONS AND LOOPS IS A WARNING SIGN
At that point, a general language generating the configuration usually serves better.
BEFORE CREATING A DOMAIN LANGUAGE, CONSIDER A LIBRARY INSTEAD
It is almost always the better answer.
