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A category quietly stopped growing

A breakdown by subscription status has looked stable for two months, while the total has grown. One status has been flat since a mobile release, and no check has fired. Types are unchanged and no schema diff exists.

intermediate · Contracts

What you would do first

Answer before revealing anything. The value of the exercise is entirely in committing to a diagnosis you can be wrong about.

  1. 1Query the distinct values of the raw status column by week. A value appearing at the release boundary is the answer in one query.
  2. 2Compare the distinct set in raw with the distinct set in the model. The difference is what the ELSE branch swallowed.
  3. 3Correlate the first appearance with the producing team's release timeline rather than with the data platform's deploys.
  4. 4Check every other CASE expression that reads this column, because the same absorption is probably happening in several models.

What is actually going on

The trap

The fix that looks right. Read it even if you got the answer — especially then.

Add the new value to the CASE expression and move on. This breakdown is correct again, the ELSE branch is still absorbing the next unknown value, and the same silent failure is waiting in every other model that maps this column.

Resolution