01
When a simpler key stops identifying the same thing
This proposed session examines a migration rehearsal in which converting text identifiers to numbers collapsed forty-eight pairs. Participants follow the change from 1,240 source identifiers to 1,192 unique keys and the operating challenge that showed why leading zeros mattered. The case retains Harjit's approval of the design, the stop before production cutover and the ₹36 lakh rework cost over six additional weeks. We discuss how source owners can explain identity before technical standardisation, and why an exception's consequence can matter more than its share of the population. The purpose is to improve the leadership conversation around meaning-preserving change, not prescribe one data type for every system. No confidential identifiers are required for the exercise. The audience should leave with questions about what a transformation must preserve, who can challenge its assumptions and what evidence is needed before a programme describes a migration as ready to proceed into production.