I’d answer this differently: object and graph databases operate on two different levels of abstraction. An object database’s main data elements are objects, the way we know them from an object-oriented programming language. A graph database’s main data elements are nodes and edges. An object database does not have the notion of a (bidirectional) edge … Read more
Whether you should use a property, a label or a node for the category depends on how you will be querying the data. (I’ll assume here that you have a fairly small, fairly fixed set of categories.) Use a property if you won’t be querying by category, but just need to return the category of … Read more
Few thoughts on this: I would try modelling your Neo4j domain model to include the attributes of each node in the graph. By separating your data into two different data stores you might limit some operations that you might want to do. I guess it comes down to what you will be doing with your … Read more
That’s in the reference docs, see http://docs.neo4j.org/chunked/stable/query-set.html#set-set-a-label-on-a-node, you need to use set to a add a label to a existing node: match (n {id:desired-id}) set n :newLabel return n
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). … Read more
As mentioned in this issue comment and fixed by this commit, since Neo4J 3.1, you can add a line in /etc/default/neo4j: NEO4J_ULIMIT_NOFILE=60000 to set the ulimit setting (60000 open files) for the service. There is no need anymore to use /etc/security/limits.conf on debian to set the number of open files.
We have a social graph in which in a day we add almost 1 millions of node and twice as many edges. We started with neo4j graph because yes, it is very fast due to fact that its storage is on the same machine on which graph engine runs. But following are the experiences that … Read more
You can put this condition in the WHERE clause: MATCH (n) WHERE n:Male OR n:Female RETURN n EDIT As @tbaum points out this performs an AllNodesScan. I wrote the answer when labels were fairly new and expected the query planner to eventually implement it with a NodeByLabelScan for each label, as it does for the … Read more
using regular expressions: http://neo4j.com/docs/developer-manual/current/#query-where-regex start n = node(*) where n.Name =~ ‘.*SUBSTRING.*’ return n.Name, n;
To get all distinct node labels: MATCH (n) RETURN distinct labels(n) To get the node count for each label: MATCH (n) RETURN distinct labels(n), count(*)