In neo4j 3.2.1 this feature has been relocated to the bottom left corner, under the gear icon: “Connect result nodes” (checked by default, thus returning all relationships between nodes included in the result).
Since Cypher’s ASCII-art syntax can only let you specify one linear chain of connections in a row, the comma is there, at least in part, to allow you to specify things that might branch off. For example: MATCH (a)–>(b)<–(c), (b)–>(d) That represents three nodes which are all connected to b (two incoming relationships, and one … Read more
There is a poorly documented difference between installing neo4j using an installer (which is most common) versus from a zip or tar file. (A) When you install neo4j using an installer, the installer configures the neo4j server to look for the plugins folder in the database folder (i.e., under the default.graphdb folder). (B) When you … Read more
Specifying the uniqueness of paths is a planned feature of cypher. So right now we have to ascertain that no node is a duplicate in the path. There is an ALL predicate that must hold true for all elements of a collection (which a path is). And with filter you can extract the elements of … Read more
I used a graph database in a previous job. We weren’t using neo4j, it was an in-house thing built on top of Berkeley DB, but it was similar. It was used in production (it still is). The reason we used a graph database was that the data being stored by the system and the operations … Read more
Update 01/10/2013: Came across this in the Neo4j 2.0 reference: Try not to use optional relationships. Above all, don’t use them like this: MATCH a-[r?:LOVES]->() WHERE r IS NULL where you just make sure that they don’t exist. Instead do this like so: MATCH a WHERE NOT (a)-[:LOVES]->() Using cypher for checking if relationship doesn’t … Read more
The browser is telling you that: It is handling your query by doing a comparison between every Gene instance and every Chromosome instance. If your DB has G genes and C chromosomes, then the complexity of the query is O(GC). For instance, if we are working with the human genome, there are 46 chromosomes and … Read more
There are several options to do this. I’ll illustrate some of the more popular ones. Named Graphs / Quads In RDF, named graphs are subsets of an RDF dataset that are assigned a specific identifier (the “graph name”). In most RDF databases, this is implemented by adding a fourth element to the RDF triple, turning … Read more