Version control for data mappings, and why Excel does not have it
Engineers have had real version control for decades. Per-change author, timestamp, description, and complete diff against previous state. Two engineers edit the same file at the same time; the system reconciles or flags a conflict. The history is queryable indefinitely with no degradation.
Then the same engineers move to a data team and discover the mapping files are in Excel on SharePoint, where "version control" means "the file has fifty versions and you can hopefully open one of the older ones".
The gap is wider than it looks.
What proper version control gives you
- Per-change attribution. Not "the file was modified by Alex at 3pm". The specific cell, in the specific row, changed from X to Y at this exact time, by Alex.
- Per-change reason. Required field. "Adding new currency for the Brazilian launch." "Correcting typo." "Reclassifying customer 14271 from wholesale to retail at finance request."
- Parallel edits. Two people edit different parts at the same time without overwriting. If they touch the same part, the conflict is flagged before save.
- Time travel. State of the data at any past timestamp.
- Reversion. Roll back to a specific past state; the rollback itself is recorded as a new change.
What Excel pretends to give you
| Feature | What it actually does |
|---|---|
| SharePoint version history | Versions the file, not the data |
| "Track changes" | Deprecated; requires mode-on before the change |
| Manual changelog tab | Filled in when humans remember |
| Comment column | Optional, usually empty |
| Locked cells | Bypassed by anyone with the password |
These look like version control from far away. They fail under pressure.
SharePoint saves the file at save events, not change events. Two changes in one save are indistinguishable. Bulk pastes are indistinguishable from one careful edit.
Excel's "Track Changes" requires the mode to be enabled before the change. If it is off, the change is invisible. Microsoft deprecated the feature in 2016.
Manual changelogs are written when humans remember. By the time the question matters, the entry is missing.
Why this matters
Sooner or later, someone important asks about the past. An auditor. A regulator. A controller asking how a specific balance-sheet number got there. A CEO asking why a customer is in the wrong segment.
The typical version of that conversation: a controller notices that a customer's classification was changed from wholesale to retail at some point in the last quarter, and that the change affected which revenue stream the customer landed in. With version control, the question is one query: when, by whom, with what reason. Without it, the answer is a half-day of forensics or a guess.
A purpose-built mapping system records changes by row, by user, with old and new values. gridmap also supports soft delete with restore, so accidental deletions are recoverable instead of investigative.
If your team cannot answer "who changed this value, when, and why" in two clicks, you do not have version control. You have a backup.