A Halloween data horror story 🎃

We were migrating system U to system P.

Q: How to calculate user onboard duration?

A: We don’t, we copy the value from [deprecated system] field XYZ_OBD_WK

Q: Can we ask the developer for that calculation?

A: He/she has left 2 years ago.

Q: Can we see the code?

A: Here it is - a single 5k-line stored procedure 😱

Last modified on 2025-10-18