Before you invest in data retention

The advice here is unglamorous, which is probably why it gets skipped. Before you spend anything on data retention, it is worth confirming a few things are already true.

Numbers get quoted in meetings long after anyone remembers how they were calculated. It is the sort of thing that looks like polish right up until it costs you an enquiry.

Prerequisites

• You can describe the outcome you want in one sentence
• Someone owns it after the work is done
• Keeping everything forever is a liability, not an asset
• You have a way to tell whether it worked

Common failure modes

Retention rules should be written down and enforced automatically. This is the sort of thing that compounds, quietly, in both directions. It is the sort of thing that looks like polish right up until it costs you an enquiry.

Deletion has to work across backups too. The teams that handle this well are rarely the ones with the biggest budgets. It is the sort of thing that looks like polish right up until it costs you an enquiry.

How to tell if yours is fine

Data outlives the applications built on top of it, which is why the model deserves more thought than the screens. Three things worth confirming about data retention before you move on:

• Someone can say what the current setup is without going to look
• Retention rules should be written down and enforced automatically — and you know whether that is true here
• There is a way to tell whether the last change to this helped

The point is not perfection, it is knowing which of these you have consciously chosen to skip.