Overview
The Document Model
The data in this model is stored inside documents. Each document consists of a set of properties which are called fields. Fields can hold primitive data types, embedded documents, or arrays of other values.
Difference to a relational database
A relational Database is a set of tables where you can store your data in a predefined scheme. Means you have a fixed number and typ of attributes in each table. In a document database you have more options. Every document can be different structured so you do not need a schema for the database. But it also possible to predefine a schema if you use Classes and set the fields as mandatory.
| Relational Model | Document Model | OrientDB Document Model |
|---|---|---|
| Table | Collection | Class or Cluster |
| Row | Document | Document |
| Column | Key/value pair | Document field |
| Relationship | not available | Link |
When to use a document database
If you have unstructured data which you can not describe as a set of columns.