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Neo4j as a graph database, the origin of its name is actually related to the way it is stored at the bottom. The bottom layer of Neo4j will store user-defined nodes and relationships in a graph. In this way, efficient implementation starts from a node and finds out the relationship between the two nodes through the relationship between nodes.

Neo4j is commonly used in the following usage scenarios:

Social Network

Graph-based search

Recommendation engine

Enterprise Infrastructure and Network Architectur

Such as: Tianyan check the relationship between the enterprises of the website and so on.

This article focuses on the deployment of the HA environment, simulating three nodes on a single server. The actual production environment can be deployed separately on different servers, and the configuration file can be modified according to different IP and ports.

1 、 Java environment [root@appcan-t-app-7 ~] # more / etc/profileexport JAVA_HOME=/usr/local/jdk1.8.0_60export JRE_HOME=$ {JAVA_HOME} / jreexport CLASSPATH=.:$ {JAVA_HOME} / lib:$ {JRE_HOME} / libexport PATH=$ {JAVA_HOME} / bin:$PATH [root@appcan-t-app-7 ~] # java-versionjava version "1.8.0 October 60" Java (TM) SE Runtime Environment (build 1.8.0_60-b27 ) Java HotSpot (TM) 64-Bit Server VM (build 25.60-b23 Mixed mode) 2. Download the community version of wget https://neo4j.com/artifact.php?name=neo4j-community-3.4.9-unix.tar.gz (current latest version) You can go to the website to choose the applicable version) 3. Install tar xf neo4j-community-3.4.9-unix.tar.gz-C / usr/local/cd / usr/local/neo4j-community-3.4.9-unix/./bin/neo4j-installer installsystemctl status neo4j-service4, HA configuration:

Complete the HA configuration by modifying the conf/neo4j.properties and conf/neo4j-server.properties files.

Node01: (1) conf/neo4j.properties:##ha.server_id = 1ha.server = 127.0.0.1:6363online_backup_server = 127.0.0.1:6366ha.cluster_server = 127.0.0.1:5001ha.initial_hosts = 127.0.0.1 * (2) conf/neo4j-server.properties##org.neo4j.server.database Location=data/graph.dborg.neo4j.server.webserver.port=7474org.neo4j.server.webserver.address=0.0.0.0org.neo4j.server.webserver.https.port=7484org.neo4j.server.database.mode=HANode02: (1) conf/neo4j.properties:##ha.server_id = 2ha.server = 127.0.0.1:6364online_backup_server = 127.0.0.1:6367ha.cluster_server = 127.0.0.1:5002ha.initial_hosts = 127.0.0.1 .0.1: 5002127.0.0.1 purl 5003 * * (2) conf/neo4j-server.properties##org.neo4j.server.database.location=data/graph.dborg.neo4j.server.webserver.port=7475org.neo4j.server.webserver.address=0.0.0.0org.neo4j.server.webserver.https.port=7485org.neo4j.server.database.mode=HANode03: (1) conf/neo4j.properties:##ha.server_id = 3ha.server = 127.0.0.1:6365online _ backup_server = 127.0.0.1:6368ha.cluster_server = 127.0.0.1:5003ha.initial_hosts = 127.0.0.1virtual 5001127.0.0.1virtual 5002127.0.0.1 * (2) conf/neo4j-server.properties##org.neo4j.server.database.location=data/graph.dborg.neo4j.server.webserver.port=7476org.neo4j.server.webserver.address=0.0.0.0org.neo4j.server. Webserver.https.port=7486org.neo4j.server.database.mode=HA

Start in turn:

. / bin/neo4j start

Detect:

# jps

17131 CommunityBootstrapper

17324 CommunityBootstrapper

16959 CommunityBootstrapper

5. WEB interface

WEB interface display:

6. Basic Cypher operations [add, delete, modify and query] (1) insert node:

Insert a node of the Person category, and the node has an attribute name with a value of Andres

CREATE (n:Person {name: 'Andres'}); (2) insert edges:

Insert a directed edge from a to b, and the edge category is Follow

MATCH (a:Person), (b:Person) WHERE a.name = 'Node A' AND b.name = 'Node B'CREATE (a)-[r:Follow]-> (b); (3) Update the node:

Update a node of the Person category and set the new name.

MATCH (n:Person {name: 'Andres'}) SET n.name =' Taylor'; (4) Delete the node and the edges connected to it:

In Neo4j, if a node is connected by an edge, it cannot be deleted alone.

MATCH (n:Person {name:'Andres'}) DETACH DELETE n; (5) Delete edge: MATCH (a:Person)-[r:Follow]-> (b:Person) WHERE a.name = 'Andres' AND b.name =' Taylor'DELETE r; (6) query statement:

Shortest path:

MATCH (ms:Person {name:'Andres'}), (cs:Person {name:'Taylor'}), p = shortestPath ((ms)-[r:Follow]-(cs)) RETURN p

Query the relationship between two nodes:

MATCH (a:Person {name:'Andres'})-[r]-> (b:Person {name:'Taylor'}) RETURN type (r)

Query all Follower of a node:

MATCH (: Person {name:'Taylor'})-[r:Follow]-> (Person) RETURN Person.name; (7) create Neo4j database

Create a uniqueness constraint with an indexing effect similar to the primary key in a relational database. Note that this can only be set when no data has been inserted into the database.

CREATE CONSTRAINT ON (a:Person) ASSERT a.name IS UNIQUE

Create an index:

CREATE INDEX ON: Person (name)

View all the number of nodes and edges:

MATCH (n) RETURN count (n); MATCH ()-- > () RETURN count (*); reference:

1. Https://www.cnblogs.com/valleylord/p/3676607.html

2. Http://www.cnblogs.com/rubinorth/p/5853204.html

3. Https://neo4j.com/docs/2.0.2/ha-setup-tutorial.html

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