Using indexes

It is possible to create and use all the index types described in Cypher Manual → Indexes.

This section demonstrates how to work with indexes with an example of a user database. For information about how to create an index on all User nodes that have a username property, see Cypher Manual → Create a single-property index for nodes.

The source code used in this example is found at: EmbeddedNeo4jWithIndexing.java

Begin with starting the database server:

DatabaseManagementService managementService = new DatabaseManagementServiceBuilder( databaseDirectory ).build();
GraphDatabaseService graphDb = managementService.database( DEFAULT_DATABASE_NAME );

Then, you can configure the database to index users by name. This only needs to be done once.

Note that schema changes and data changes are not allowed in the same transaction. Each transaction must either change the schema or the data, but not both.

IndexDefinition usernamesIndex;
try ( Transaction tx = graphDb.beginTx() )
{
    Schema schema = tx.schema();
    usernamesIndex = schema.indexFor( Label.label( "User" ) )  (1)
            .on( "username" )                                  (2)
            .withName( "usernames" )                           (3)
            .create();                                         (4)
    tx.commit();                                               (5)
}

1	A single-property index is defined on a label in combination with a property name. Start your index definition by specifying the node label.
2	Next, define the property that should be part of this index. Index all nodes with the `User` label, that also have a `username` property. This way, you can find `User` nodes by their `username` properties.
3	An index always has a name. If not specified, it will be generated for you.
4	Calling `create` is necessary for the index definition to be created in the database. This index is now created, but it still only exists in your current transaction.