Can we Use programming features in neo4j query like as we have pl-sql in sql. I need some loops and other programming features in Cypher query.Please can anyone tell is it possible.
Yes. You have two options
Server Plugins
Unmanaged Extensions
Server Plugins
The server’s functionality can be extended by adding plugins.
Plugins are user-specified code which extend the capabilities of the database, nodes, or relationships.
The neo4j server will then advertise the plugin functionality within representations as clients interact via HTTP.
Related
I have read the Neo4j Java Developer Reference Document recently, but I didn't see the information about Undo/Redo/Rollback, so I wonder is the Neo4j support these operations?
neo4j does not support undo/redo, but it does support transactions (so, rollbacks are supported).
See the specific documentation for Java, Cypher, the HTTP API, and Bolt.
as I was wandering in the Web looking for a Gremlin implementation for Neo4j I found these two possible solutions:
https://github.com/thinkaurelius/neo4j-gremlin-plugin
http://tinkerpop.incubator.apache.org/docs/3.0.2-incubating/#neo4j-gremlin
Does anybody know what is the difference between the two in practice?
I saw that 1. is a Neo4j plugin while it's not really clear to me what the second is, and if it would lock the entire database thus not allowing other connections (I noticed that it requires the path to the data folder).
Which one is preferred in the neo4j community?
Cheers,
Alberto
I'm not sure there's really a difference as there isn't a direct comparison to be made. The second link is to the TinkerPop project and specifically to the Neo4j implementation of TinkerPop APIs. It runs in an embedded mode and does not yet have support for HA (though we hope to have that soon). The Neo4j implementation can be run in Gremlin Server which let's you send Gremlin to it as a REST, websockets, etc endpoint.
The project in the first link you provided uses that implementation to allow you to send Gremlin to Neo4j Server - so the first project depends on the second.
Your rule of thumb should be activity in the source code.
neo4j-gremlin-plugin has 3 commits this year - https://github.com/thinkaurelius/neo4j-gremlin-plugin/commits/master
tikerpop is much more active - https://github.com/apache/incubator-tinkerpop/commits/master/neo4j-gremlin/src/main/java/org/apache/tinkerpop/gremlin/neo4j
neo4j-gremlin-plugin
Extending existing Neo4j server with support for Gremlin Query Language.
TinkerPop Neo4j-Gremlin
Extending Gremlin console with support for Neo4j server.
I am working on scientific project and i am currently studying the possibility to use graph databases.
The software architecture that we developed is service oriented with android clients.
I want to know if Neo4j can be used in my case and the most important if i can execute Cypher requests from Android.
Cheers
As #MarcoCI mentioned you can emit Cypher queries via REST. Neo4j therefore has the transactional Cypher endpoint and the legacy Cypher endpoint.
Another idea would be to encapsulate your actions on a use-case level within unmanaged extensions and let your Android client trigger those. Unmanaged extensions are basically java code deployed to the Neo4j server that expose new REST endpoints. Within its implementation you might use Cypher or core API.
How can I turn off mandatory transactions in Neo4j 2.0? I need to do this as the library I am using does not support the 2.0 transactional API yet.
As you've said, in Neo4j 2.0 transactions are mandatory and there is no way to switch this off. If you're relying on Cypher be aware that the Cypher's ExecutionEngine automatically opens and closes a transaction if there is no one available from outside.
Depending on your environment and architecture you can use cross-cutting concerns to manage transactions separately from your code base. Think of java servlet filters, and aspect with aspectj, byte code manipulation, Groovy MOP magic, and other technologies. For a more focussed answer you should give more insight in your project regarding used languages, frameworks and architecture.
what if you are running neo4j in read-only mode? and you are more interested in speed rather than concurency as there is no race conditions.
from http://neo4j.com/docs/stable/transactions-isolation.html there will always be a transaction :/
In order to store hierarchical data, can a graph database (Neo4j) be viewed as an alternative to JCR based solutions (ModeShape, JackRabbit)? Or do they belong to 2 different level of abstraction meaning that a JCR implementation could use Neo4j under the hood?
Thank you for your help.
Both, people are building CMS applications with Neo4j as storage backend (see http://structr.org)
A JCR implementation could also be done using Neo4j, some people worked on that in the past, we also have a group using Neo4j as backend storage for Apache Shindig.
You also might want to take a look at OrientDB (http://www.orientdb.org/) which combines features of a Graph-DB (as Neo4j) with those of a Document-DB. There even seems to be a prototype implementation using OrientDB as a storage-adapter for Jackrabbit (https://github.com/eiswind/jackrabbit-orient) that illustrates the implementation of such a hybrid approach.