System design reviews: what to get right first

This is one of those topics that looks small until it costs you something. If you only fix one thing about system design reviews this quarter, make it the first item below.

The right architecture for a team of three is the wrong one for a team of thirty, and vice versa. The failure mode is not doing it wrong, it is doing it once and assuming it stays done.

Start here

An hour of review before the build saves weeks of rework. This is the sort of thing that compounds, quietly, in both directions. The practical test is whether someone new to the project could tell, in a minute, that it had been handled.

Then this

Write the design down. That sounds obvious written down. It is still the thing most often skipped. Doing this properly once is usually cheaper than doing it approximately three times.

Eventually

Invite the person who will be on call for it. That sounds obvious written down. It is still the thing most often skipped. Write the reasoning down alongside the decision, because the reasoning is what changes first.

The short version

Architecture is the set of decisions that are expensive to reverse, which is the only reason they deserve the name. Three things worth confirming about system design reviews before you move on:

• Someone can say what the current setup is without going to look
• Invite the person who will be on call for it — and you know whether that is true here
• There is a way to tell whether the last change to this helped

If you want a second opinion on how yours is set up, ask.