Search code examples
orientdb

The difference between referenced relation and foreign key?

I think that referenced relation is one record has a property which value is the record id of the other record, at the same time, foreign key is that one record has the primary key of the other record. Why the doc2.1.x emphasize that the referenced relation avoid the costly join operation?

Solution

  • OrientDB manages relations as physical links to records, assigned only once when the edge is created. OrientDB not use JOIN. Instead, use the links that has a relationship managed by storing the RID target in the record source. It 'very similar to store a pointer between two objects in memory. An edge connects two vertices and must have: a unique identifier, links vertex incoming, outgoing link vertex and label that defines the type of connection.

    This is a little example:

    enter image description here

    Hope it helps