I am going to use ElasticSearch for as the search repository in my application. I have a few questions regarding what is best practice when it comes to organizing objects in the search index when the objects have associations/relations to each other.
From what I know search indexes is a flat structure and doesn't work with the concept of relations in the same way as a database.
Let say you have these domain objects:
Person: - Has a one-to-many relationship with Car
Car: - Is owned by one Person, many-to-one with Person
Department: - Each Department have many People and each Person may belong to many Department, many-to-many
What would be the best way to store this in the search index? What are the options? For instance I want to find all the people belonging to a certain deparment, or all people where the car has more than 300 bhp. I am using the Java client API if it matters.
Elastic search (or Lucene) isn't a relational database, so you would need to flatten your relationship model.
Try to model a view that gets this structure -
Car|Person|Department
This will give you all attributes required to lookup a car. This can be imported into a document for Car.
Similarly
Person|Department
will give you all information for a person. This will help you lookup a Person
Department can be a third document.
You can have multiple documents for each entity. But the relationship needs to be translated as a property of the entity.