> For the complete documentation index, see [llms.txt](https://gchandra.gitbook.io/data-warehousing/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gchandra.gitbook.io/data-warehousing/data-warehousing-concepts/dimensional-modelling/snowflake-schema.md).

# Snowflake Schema

Snowflake is an extension of the Star Schema. 

Dimension tables are further normalized and can have their categories.

One or more lookup tables can describe each dimension table. Normalization is recursive until the model is fully normalized.

Check dim\_store, dim\_product, and dim\_time and compare with Star Schema.

<figure><img src="https://2629735788-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F3G2NQEHaUSzehWzaKvXK%2Fuploads%2Frr0KHTSEBkNTkPSUB7et%2Fdw_sf_schema_01.png?alt=media&amp;token=97b2828b-893c-4be0-aae9-1e0f61acfab0" alt=""><figcaption></figcaption></figure>

Check the Sales Order Schema

<figure><img src="https://2629735788-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F3G2NQEHaUSzehWzaKvXK%2Fuploads%2Fh2Tg691CNHYchYBPdQtS%2Fdw_sf_schema_02.png?alt=media&amp;token=b746d394-7008-446a-963f-aa6e8cca4a60" alt=""><figcaption></figcaption></figure>

#### **Advantages**

Better data quality. Less disk space is used compared to Star Schema.

#### **Disadvantages**

The major disadvantage is too many tables to join. Poorly written queries result in a decrease in performance significantly.