CODEWITHSUNDEEP
spring-dataspring-data-neo4jspring-data-neo4j-4
Qualaelay
Qualaelay

Reputation: 753

Spring-data-neo4j v4, why no index

According to the migration of SDN (Spring-data-neo4j) v3 to SDN4, Indexes are not present anymore, so this is not foreseen to work anymore.

@NodeEntity
public class User extends Unversioned{
    @Indexed(unique=true,failOnDuplicate = true) // <-- THIS
    private String login;
    ...
}

According to here or there, no-one seems surprised. Isn't that the "point" to have constraints defined on the model itself ?

The mission defined on the main page of Sring-data:

Spring Data’s mission is to provide a familiar and consistent, Spring-based programming model for data access while still retaining the special traits of the underlying data store.

Even when comparing to the latest Spring-data-JPA official example, constraints are still defined on the model:

@Entity
public class Customer extends AbstractEntity {

    private String firstname, lastname;

    @Column(unique = true)
    private EmailAddress emailAddress;

Allowing constraints to be defined on the very java-based-model seemed to me to be the less error-prone system. How are we supposed to build a model consistent if the model & constraints are decoupled ? What am I missing ?

Upvotes: 0

Views: 520

Answers (2)

František Hartman
František Hartman

Reputation: 15086

I will try to give you an answer "from the trenches". I used SDN 3.x quite a lot, now I use 4.x, I also use spring data mongo, which has @Indexed annotation.

I agree it is very convenient when you just want to create an index on a property.

But there are several problems in the long run. When the application is deployed and maintained I had to resort to managing indexes in code, not declaratively.

These include

  • renaming the property, won't delete the old index
  • changing the index (e.g. making it unique constraint)
  • these annotation usually don't provide all the possibilities of the native database index definition
  • class hierarchies - what if you have an @Indexed on a property in a base class - what index(es) are created? Just for the base class label? (or collection in mongo), all children...?

In the end you trade one line with @Indexed annotation for another

@Autowired
private Neo4jOperations operations;

@PostConstruct
public void createIndexesAndConstraints() {
    ...
    operations.query("CREATE INDEX ON :Person(email)", EMPTY_MAP);
    ...
}

Upvotes: 2

Luanne
Luanne

Reputation: 19373

As of SDN 4, index management is considered to be out of scope for the mapping framework, and it is recommended that they be managed outside of Spring.

More info: http://docs.spring.io/spring-data/neo4j/docs/current/reference/html/#reference_programming-model_indexing

Upvotes: 1

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