Migrating thousands of members without inventing anything
How we moved records, dues and documents from a legacy membership system into the PDR platform — and why we refused to fill in missing data.
A new system can never be more trustworthy than the data it inherits. The biggest risk in a migration is filling empty fields with "reasonable" values or silently merging contradictory records. That means a wrong ledger from day one.
The rule: if it isn't in the source, it isn't in the target
In the PDR platform migration we moved member records, dues history and documents off the legacy system without inventing a single value. Every migrated file was matched to its source record and verified on disk.
Records the source could not resolve were not auto-corrected. Each one went onto a separate list, and the decision was left to the organisation that owns the data.
Sometimes the right answer in a migration is "we don't know". The system's job is to make that uncertainty visible, not to paper over it.
Without touching the old system
The old application was never modified during the migration. Writes on the new platform sat behind a separate switch and were enabled only after the data was verified. The migration was designed as a process that reads from the old system and proves its result — not one that changes it.