Three myths about database migrations

The gap between knowing this and actually doing it is where most teams lose ground. A few things about database migrations that get repeated more often than they get checked.

Most development decisions are really maintenance decisions wearing a different hat. Most teams find the first pass takes an afternoon and the maintenance takes minutes a month.

“It only matters for big sites”

Migrations should be reversible or provably safe. It is worth being explicit about, because assumptions differ quietly. Doing this properly once is usually cheaper than doing it approximately three times.

“We can deal with it after launch”

Sometimes true, usually expensive. None of that requires a large budget, only a decision and someone to own it.

“Our platform handles it”

Backwards-compatible changes let you deploy without downtime. The teams that handle this well are rarely the ones with the biggest budgets. Budget a little time for it every quarter and it never becomes a project of its own.

What this looks like day to day

The question is rarely whether something can be built, but what it costs to keep running afterwards. Three things worth confirming about database migrations before you move on:

• Someone can say what the current setup is without going to look
• Migrations should be reversible or provably safe — and you know whether that is true here
• There is a way to tell whether the last change to this helped

Worth checking on your own setup before it becomes someone else's problem to fix.