> ## Documentation Index
> Fetch the complete documentation index at: https://docs.usefactor.app/llms.txt
> Use this file to discover all available pages before exploring further.

# Data Migration Example

> Schema change cascading impact

## The PR

**Title**: Add required `company_id` column to customers table

**Summary**:
Our system is adding multi-company support. Each customer must belong to a company. This PR adds a `company_id` column to the customers table and makes it required.

**Changes**:

* Database migration: Add `company_id` column (NOT NULL)
* Application code assumes `company_id` is always present
* Reporting queries updated to filter by company\_id

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## Factor Analysis

### Verdict

```
BLOCK_REVIEW
```

This schema change has cascading impacts that require careful coordination.

***

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