Three myths about caching layers

Most teams know this matters. Fewer have decided who owns it. A few things about caching layers that get repeated more often than they get checked.

The right architecture for a team of three is the wrong one for a team of thirty, and vice versa. The practical test is whether someone new to the project could tell, in a minute, that it had been handled.

“It only matters for big sites”

Caching is easy until something has to be invalidated. Small and consistent beats large and occasional here. It is the sort of thing that looks like polish right up until it costs you an enquiry.

“We can deal with it after launch”

Sometimes true, usually expensive. That sounds obvious written down. It is still the thing most often skipped.

“Our platform handles it”

A stale cache with no expiry is a future incident. This is the sort of thing that compounds, quietly, in both directions. The teams that stay on top of it are the ones who put it on a calendar rather than a wish list.

How to tell if yours is fine

Most systems fail at the seams rather than inside any one component. Three things worth confirming about caching layers before you move on:

• Someone can say what the current setup is without going to look
• Caching is easy until something has to be invalidated — and you know whether that is true here
• There is a way to tell whether the last change to this helped

Most of the value here comes from doing the first two things, not all of them.