The Kimball Group catalogs eight types, numbered 0 to 7. Types 1 and 2 cover most needs; the rest handle special cases or combine them:
| Type | Technique | Use it for |
|---|---|---|
| 0 | Retain the original value | Signup date, first channel |
| 3 | Add a prior-value column | One planned change, such as a sales-region realignment |
| 4 | Split volatile attributes into a mini-dimension | Rapidly changing bands (age, loyalty tier) |
| 5 | Mini-dimension plus a Type 1 outrigger | Current band visible from the base dimension |
| 6 | Type 2 rows with Type 1 "current" columns | History and today's value in one row |
| 7 | Facts carry the Type 2 key and a durable key | Both as-was and as-is reporting |
Outside Kimball's catalog, "Type 4" often means a separate history table beside a current-only table, which is how SQL Server 6 's system-versioned temporal tables work. Check which meaning a colleague intends.