> For the complete documentation index, see [llms.txt](https://til.notdu.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://til.notdu.com/database/intro-to-database-systems/database-storage-ii/decomposition-storage-model-dsm.md).

# Decomposition storage model (DSM)

The DBMS stores the values of a single attribute for all tuples contiguously in a page

-> Also known as a "column store"

Ideal for OLAP workloads where read-only queries perform large scans over a subset of the table's attributes.

![](https://2548495579-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTsnKOX7xLvOtvOXY9MlI%2Fuploads%2FmSJZNYl9TcVWjZu98dQB%2Fimage.png?alt=media\&token=f4deafae-521e-4501-bb8e-7fbc75ff0274)

#### Advantages

* Reduce the amount wasted I/O because the DBMS only reads the data that it needs
* Better query processing and data compression (more on this later)

#### Disadvantages

Slow for pointer queries, inserts, updates, and deletes because of tuple splitting/stitching