Node identifiers in neo4j

I'm new to Neo4j - just started playing with it yesterday evening.

I've notice all nodes are identified by an auto-incremented integer that is generated during node creation - is this always the case?

My dataset has natural string keys so I'd like to avoid having to map between the Neo4j assigned ids and my own. Is it possible to use string identifiers instead?

Solution 1:

Think of the node-id as an implementation detail (like the rowid of relational databases, can be used to identify nodes but should not be relied on to be never reused).

You would add your natural keys as properties to the node and then index your nodes with the natural key (or enable auto-indexing for them).

E..g in the Java API:

Index<Node> idIndex = db.index().forNodes("identifiers");

Node n = db.createNode();
n.setProperty("id", "my-natural-key");
idIndex.add(n, "id",n.getProperty("id"));

// later
Node n = idIndex.get("id","my-natural-key").getSingle(); // node or null

With auto-indexer you would enable auto-indexing for your "id" field.

// via configuration 
GraphDatabaseService db = new EmbeddedGraphDatabase("path/to/db",
 MapUtils.stringMap( 
    Config.NODE_KEYS_INDEXABLE, "id", Config.NODE_AUTO_INDEXING, "true" ));

// programmatic (not persistent)
db.index().getNodeAutoIndexer().startAutoIndexingProperty( "id" );

// Nodes with property "id" will be automatically indexed at tx-commit
Node n = db.createNode();
n.setProperty("id", "my-natural-key");

// Usage
ReadableIndex<Node> autoIndex = db.index().getNodeAutoIndexer().getAutoIndex();
Node n = autoIndex.get("id","my-natural-key").getSingle();

See: http://docs.neo4j.org/chunked/milestone/auto-indexing.html And: http://docs.neo4j.org/chunked/milestone/indexing.html