Working with index in Neo4j

问题:

I've been going through the Neo4J and Neo4J C# client..

The neo4jclient wiki helped me to with node crud operations.. however the wiki ends there abruptly.. I poked around the test methods in source code and managed to understand about relationships and searched online to understand how indexing works.

So far, here's what I have, roughly:

//create indexing on user and car
client.CreateIndex("User", new IndexConfiguration() { Provider = IndexProvider.lucene, Type = IndexType.fulltext }, IndexFor.Node); 
client.CreateIndex("Car", new IndexConfiguration() { Provider = IndexProvider.lucene, Type = IndexType.fulltext }, IndexFor.Node);

//create user
client.Create(new User() { Name = "Dovakiin", Job = "Dragon Slayer" });
client.Create(new User() { Name = "Ulfric stormcloak", Job = "Imperial Slayer" });

//create Car
client.Create(new Car() { Name = "Paarthurnax", Modal = 212 });

//User owns car relationship
client.CreateRelationship(userRef, new Owns_CarRelationship(CarRef));

This is where I am stuck now.. When I try to look for the user by name, my cipher query is returning zero results:

 start u=node:User(Name="Dovakiin") return u;

and I don't quite understand why it returns zero nodes when clearly

start n=node(*) return n;

shows all nodes.

Am I missing something else while indexing? Or is this not index related at all? Do I not need to add each node to the index?

All I am trying to do, is select the node with a given property: Name = "Dovakiin" in this case.. How do I select this please?

回答1:

Just to expand on ulkas' answer, if you want to enable auto indexing and found the documentation a little confusing (like I did the first time I read it), this is how you set it up.

Let's say you want to automatically index some node properties; say, "name" and "job". Open up the /conf/neo4j.properties file and you should see something like this:

# Autoindexing

# Enable auto-indexing for nodes, default is false
#node_auto_indexing=true

# The node property keys to be auto-indexed, if enabled
#node_keys_indexable=name,age

You then have to edit the file to the following:

# Autoindexing

# Enable auto-indexing for nodes, default is false
node_auto_indexing=true

# The node property keys to be auto-indexed, if enabled
node_keys_indexable=name,job

Once this is done, in order for auto indexing to take effect, you'll have to restart neo4j. Also, as a side note, any currently existing nodes won't be auto indexed, which means you'll have to recreate them. If you don't want to start from scratch, here's some documentation on how to update them: http://docs.neo4j.org/chunked/milestone/auto-indexing.html#auto-indexing-update-removal (I've never tried it).

Then you can start finding nodes like this:

start n=node:node_auto_index(name="Dovakiin"), or
start n=node:node_auto_index(job="Dragon Slayer")

Or, like this with the C# client:

Node<User> myNode = client.QueryIndex<User>("node_auto_index", IndexFor.Node, "name:Dovakiin").First();, or
Node<User> myNode = client.QueryIndex<User>("node_auto_index", IndexFor.Node, "job:Dragon Slayer").First();

You can do the same thing with with relationships as well, as soon as you set it up in the /conf/neo4j.properties file. You do it exactly the same way as with nodes.

回答2:

you must manually add the nodes to the index, something like

client.indexRef1.addToIndex(nodeRef, 'name', 'Dovakiin') client.indexRef2.addToIndex(nodeRef, 'job', 'Dragon Slayer')

there is also an automatic indexing feature in neo4j in case you want the nodes to be automatically added to the index.