Short answer
Keep every migration decision in one workbook: a cover tab, a decisions log, the object map and load order, a user map, one tab per object with field-level mapping, a picklist value map, a custom fields list and the data quality rules. The business owner signs it off before the first test load.
The tabs
| Tab | What it holds |
|---|---|
| Cover | Source and target systems, version, owner, sign-off date |
| Decisions log | Each decision, the date and who made it, for example "Closed deals older than 2019 are archived, not migrated" |
| Object map and load order | Source object, target object, load sequence and record counts |
| User map | Old users to new users, including people who have left |
| One tab per object | Source field, target field, type, transformation rule, default value, required or not |
| Picklists | Every distinct source value and its target value |
| Custom fields | Fields to create in the target, with type and description |
| Data quality rules | Rules enforced in staging before load, for example valid email, state codes, no orphan records |
Rules
- List every source field, including the ones not migrated, with the reason.
- Agree currency, time zone and character encoding before the first import.
- Test with the full file, not a sample. Matching and duplicate problems only show at full volume.
- Version the workbook. Each test load records which version it used.
- Cut over with a full load followed by a delta for changes made during the freeze.
Frequently asked questions
What is a data mapping document in a CRM migration?
A workbook that records, for every source field, where it goes in the new system, how it is transformed and why. It also holds the decisions log, load order, user map and picklist value map.
Why test a migration with the full file instead of a sample?
Matching and duplicate problems, such as family members sharing an email address, only appear at full volume. A small sample can pass and the full load still fail.
Salesforce, HubSpot, Anthropic and OpenAI change their products often. Check the official documentation before you rely on a specific setting, limit or price.