This article was originally published at [https://gist.github.com/joepie91/f9df0b96c600b4fb3946e68a3a3344af](https://gist.github.com/joepie91/f9df0b96c600b4fb3946e68a3a3344af).
**NOTE:** This is simplified. However, it's a useful high-level model for determining what kind of database you need for your project.
### Data models[](https://gist.github.com/joepie91/f9df0b96c600b4fb3946e68a3a3344af#data-models) - **Documents:** Single type of thing, no relations - **Relational:** Multiple types of things, relations between different types of things - **Graph:** Single or multiple types of things, relations between different things of the *same* type ### Consistency models[](https://gist.github.com/joepie91/f9df0b96c600b4fb3946e68a3a3344af#consistency-models) - **Strong consistency:** There is a single canonical view of the database, and everything connecting to any node in the database cluster is guaranteed to see the same data at the same moment in time. - **Eventual consistency:** There can be multiple different views of the database (eg. different nodes in the cluster may have a different idea of what the current state of the data is), but once you stop changing stuff, they will eventually converge into a single view. - **No consistency:** There's no guarantee that all nodes in the cluster will ever converge to the same view, whatsoever. ### Schemafulness[](https://gist.github.com/joepie91/f9df0b96c600b4fb3946e68a3a3344af#schemafulness) - **Schemaful:** You know the format (fields, types, etc.) of the data upfront. Fields may be optional, but every field you use is defined in the schema upfront. - **Schemaless:** You have no idea what the format is going to be. This is rarely applicable, and only really applies when dealing with storing data from a source that doesn't produce data in a reliable format. # New Page