# Dimension Sheet: [Dimension Name]

> One sheet per dimension. Complete for all dimensions in the bus matrix.

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## Overview

| Field | Value |
|---|---|
| Dimension name | |
| Business description | |
| Conformed? | Yes / No |
| Used by (fact tables) | |
| Cardinality estimate | Tens / Hundreds / Thousands / Millions |
| Primary key | |
| Source system(s) | |
| Data owner | |
| SCD default type | Type 1 / Type 2 |

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## Attribute List

| # | Attribute name | Business label | Description | Data type | SCD type | Source field | Notes |
|---|---|---|---|---|---|---|---|
| 1 | | | | | `1 / 2 / 3` | | |
| 2 | | | | | | | |

**SCD type guide:**
- **Type 1** — Overwrite. No history needed. Use for corrections, typos, low-importance changes.
- **Type 2** — New row with effective dates. History is required for this attribute. Use for analytically significant changes (customer segment, product category, pricing tier).
- **Type 3** — Add a "previous value" column. Use sparingly — only when one prior value is needed alongside current.

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## Special dimension flags

- [ ] **Degenerate dimension** — key stored directly on fact table, no dimension table required
- [ ] **Role-playing dimension** — this dimension appears in multiple roles in the same fact table (e.g., Date as order_date and ship_date)
- [ ] **Junk dimension** — groups multiple low-cardinality flags/indicators into one dimension
- [ ] **Bridge table required** — many-to-many relationship with a fact table

If role-playing: list all roles and their aliases:
| Role | Alias used in fact table | Example |
|---|---|---|
| | | |

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## Hierarchy / drill-path

> Document any natural hierarchies within this dimension (used for roll-up/drill-down in reporting).

| Level | Attribute | Example |
|---|---|---|
| Highest | | |
| | | |
| Lowest | | |

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## Known data quality issues

| Issue | Impact | Source system | Workaround / Resolution |
|---|---|---|---|
| | | | |

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## Open questions

1.
2.

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## Change log

| Date | Change | Author |
|---|---|---|
| | | |