neo4j

问题 Using neo4j 1.9.2, I'm trying to find all nodes in my graph that have a one to one relationship to another node. Let's say I have persons in my graph and I would like to find all persons, that have exactly one friend (since 2013), and this one friend only has the other person as friend and no one else. As a return, I would like to have all these pairs of "isolated" friends. I tried the following: START n=node(*) MATCH n-[r:is_friend]-m-[s:is_friend]-n WHERE r.since >= 2013 and s.since >= 2013

问题 I get this error: Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at graph_traversing.search_string.search_btnActionPerformed(search_string.java:84) at graph_traversing.search_string.access$000(search_string.java:12) at graph_traversing.search_string$1.actionPerformed(search_string.java:45) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018) at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341) at javax.swing

问题 I am wondering why my Cypher query is taking an exorbitant amount of time. Basically, I have a small family tree (two families), and I'm trying to add to each one a new node that carries some small bit of metadata so that the families are easier to keep isolated from each other when they are queried. (Thanks to @Tim Kuehn for this advice). Once I run the query to populate my two families, I have this, which is built quickly with no problems: Next, I want to create the aforementioned new nodes

问题 I have the following Cypher which I am struggling to translate into the fluent syntax: MATCH (u:User)-[:HAS_ROLE]->(r:Role)-[:ROLE_OF]->(a:App) RETURN u AS User, COLLECT([r, a]) AS Roles This is what I have so far, but I can't figure out how to return the COLLECT([r, a]) as Roles. I am using a UserDetails class to enable passing the results to a View. var results = _graphClient.Cypher .Match("(user:User)-[:HAS_ROLE]->(role:Role)-[:ROLE_OF]->(app:App)") .Return((user,role,app) => new

问题 I need breadth first search in my database. There are 3.863 nodes, 2.830.471 properties and 1.355.783 relationships. N is my start point and m is my end point in the query but It's too much slow, so I can't get result while I started the query that is in the following segment: start n=node(42),m=node(31) match p=n-[*1..]->m return p,length(p) order by length(p) asc limit 1 How can I optimize that query? Because It must finish maximum in 20 seconds. I have 8gb ram in my own computer but I

问题 I'm learning Neo4j via their tutorials. I've got the Hello World tutorial working, but I'm wondering how to view the graph in the webadmin on localhost. I assume the first step is not to call removeData() and shutDown(), but just doing that isn't accomplishing it. Basically, how can I run the the Hello World tutorial and then view/query it through webadmin? 回答1: Calling shutdown won't destroy your data. Can you share your code? Also make sure your Neo4j server points to the same database used

问题 I am interested to know if the program(below) can be improved to perform faster. Seems like, a lot of time is spent in Transaction's close() when we have constraints in place ( 90 secs with constraint , and 1 sec without ) Following is the output of the program: 2013-12-05 14:30:20,399 [main] INFO net.ahm.graph.Lab - ############# WAVE 1 ############# 2013-12-05 14:30:20,399 [main] INFO net.ahm.graph.Lab - TIME TO BEGIN TX (m-sec): 0 2013-12-05 14:30:45,296 [main] INFO net.ahm.graph.Lab -

问题 I am using neo4j 2.1.7 with java. try(Transaction transaction = this.graphDatabaseService.beginTx()) { Node user = this.graphDatabaseService.createNode(); user.setProperty("userId", userId); transaction.failure(); } So I am getting the object of GraphDatabaseService and creating a new transaction and marking it to rollback. According to their javadocs: void failure() Marks this transaction as failed, which means that it will unconditionally be rolled back when close() is called. Once this

问题 I have multiple incoming & outgoing relationships for a node (Neo4J). Each relationship has a numeric property "weight" I need to get the difference between the incoming & outgoing weights for the node. I tried this query, but return 0 for both sums, even though sum of incoming weights is 20. MATCH out=(n:Person)-[r:FRIEND]->(), in=(n:Person)<-[s:FRIEND]-() WHERE n.personid='12345' RETURN sum(r.fweight), sum(s.fweight); Also, I tried this... and it crashes/doesnt return MATCH (n:Person)-[r

问题 I was trying to build Neo4j from https://github.com/neo4j/community.git I'm building with Maven 3.05 and java 1.7.0_17 Running command: mvn clean install -Dlicense.skip=true -DminimalBuild [ERROR] Failed to execute goal org.neo4j.build.plugins:licensing-maven-plugin:1.7.5:check (list-all-licenses) on project neo4j-kernel: Generated file differs from the existing file. [ERROR] Generated: E:\neo4j\clone\gitBuild\community\kernel\target\neo4j-kernel-1.9-SNAPSHOT-NOTICE.txt [ERROR] Existing: E: