A phased migration from legacy spreadsheets
By Larry Lo
Published
Three key takeaways
- Define the source of truth, field meanings and data owner first.
- Migrate in batches with reconciliation, exceptions and recovery points.
- Restrict editing of old sheets after cutover to prevent two competing records.
Phase one: inventory and clean
List shared sheets, personal copies, formulas, hidden columns and external links. Assign purpose, owner and retention needs. Handle obsolete data under an agreed policy; migration is not a reason to collect more information or retain it forever.
Build a mapping of source field, target field, format, required rules and transformation. Preserve original values and add stable identifiers. Keep country codes in phone numbers, specify time zones for dates and currencies for amounts. A business owner should resolve duplicate customers rather than merging on name alone.
Phase two: trial a small batch
Use anonymised normal, missing, duplicate and exception examples. Reconcile input, successful and rejected counts, then check relationships, formula results and permissions. Put unconvertible items in an exception list rather than silently skipping them. Have actual users complete an enquiry-to-follow-up workflow; a successful upload is not acceptance.
Phase three: controlled cutover and recovery
Agree the change window, update freeze and final delta. During parallel operation, designate one writable system and reconcile differences so there are not two competing truths. After acceptance, make old sheets read-only with restricted access. Keep a tested recovery copy and name the person who can authorise rollback.
Before moving another workflow, confirm support ownership, correction routes and retention deadlines. ZOmate and Flower Nice Day illustrate business workflow scope; they are not evidence of spreadsheet migration speed or performance.
Questions
- Can we delete the old sheets immediately?
- First complete acceptance, recovery testing and retention checks. Keep restricted read-only copies during that period, then apply the approved disposal policy at the agreed deadline.
Limitations
Formulas, macros, historic chats and external integrations may not transfer directly. Scope cleanup, licences, API/AI usage and integrations separately. Zero downtime or zero omissions are not guaranteed; check applicable personal-data requirements.
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