# Star and Snowflake Schemas

## Star Schema

* Every dimension is represented with only one table
* Connects to the fact table using the PK-FK
* Dimension tables are independent
* Dimension tables are Non-Normalized (e.g. Customer has customer and location data)
* Fact table include key and measures
* Uses more space
* Higher Performance

<figure><img src="https://3167488510-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FN5Oxfr1ogoEGQMX2dzNM%2Fuploads%2Fj8mug8r6Mw4nQh5jKa9i%2Fimage.png?alt=media&#x26;token=7bfbcbb9-9c57-4aa2-971e-25ce546350bf" alt=""><figcaption></figcaption></figure>

## Snowflake Schema

* Extends the Star Schema
* Each Dimension table is further normalized
* Uses smaller disk space
* Lower performance

<figure><img src="https://3167488510-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FN5Oxfr1ogoEGQMX2dzNM%2Fuploads%2FiD221zuloK0zGWxYPfJv%2Fimage.png?alt=media&#x26;token=ad1a02fb-32a8-47ff-89a0-6c8184616e77" alt=""><figcaption></figcaption></figure>

## Summary

<figure><img src="https://3167488510-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FN5Oxfr1ogoEGQMX2dzNM%2Fuploads%2FKbNACXxtHCRitepnIzvK%2Fimage.png?alt=media&#x26;token=af2afa6d-dfbc-4d74-8279-db513967f20e" alt=""><figcaption></figcaption></figure>