Tag Archives: cypher

Caching Partial Traversals in Neo4j

cache_all_the_things

Sometimes you’ll find yourself looking at a traversal and thinking… “I’m going to be doing this one thing over and over again.” That sounds kind of wasteful and years of recycling have taught us not to be wasteful. Let’s take a look at an example from our past. Look back at the Neo Love application, the one with the picture of Marilyn Monroe and Groucho Marx. Let’s see what a Neo4j 2.0 version of that query would look like:

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Neo4j Spatial Part 1

http://www.iconarchive.com/show/gis-gps-map-icons-by-icons-land/Layers-icon.html

One of my new year resolutions is to do a project with Neo4j Spatial, so we’ll kick off my first blog post of the year with a gentle introduction to this awesome plugin. I advise you to watch this very short 15 minute video by Neo4j Spatial creator Craig Taverner. The man is a genius level developer, you’ll gain IQ points just listening, I swear.

The plan is to make a Restaurant Recommendation engine based on things you care about and your current location. Yes, this is baby level stuff, but we’ll start with this and see where else Neo4j Spatial can take us later on.
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Translating Cypher to Java

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The expressive power of Cypher is already awesome and getting better with the Neo4j 2.0 release. Let’s take a step back from the bleeding edge and see Cypher in 1.9.4 and how it can be translated into Java. First a simple example where we look up a User node by an index and return a list of usernames belonging to the people who are that user’s friends:

START me = node:Users(username='maxdemarzi')
MATCH me -[:FRIENDS]-> people
RETURN people.username

The Cypher statement expresses what I want even better than my botched explanation in English. So how would we do this in the Neo4j Java API?
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The Last Mile

Last-Mile

The “last mile” is a term used in the telecommunications industry that refers to delivering connectivity to the customers that will actually be using the system. In the sense of Graph Databases, it refers to how well the end user can extract value and insight from the graph. We’ve already seen an example of this concept with Graph Search, allowing a user to express their requests in natural language. Today we’ll see another example. We’ll be taking advantage of the features of Neo4j 2.0 to make this work, so be sure to have read the previous post on the matter.

We’re going to be using VisualSearch.js made by Samuel Clay of NewsBlur. VisualSearch.js enhances ordinary search boxes with the ability to autocomplete faceted search queries. It is quite easy to customize and there is an annotated walkthrough of the options available. You can see what it does in the image below, or click it to try their demo.

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Neo4j 2.0 is coming

neoiscoming

House Neo4j of Graph Databases is one of the Great Houses of NOSQL and the principal noble house of The Graph; many lesser houses are sworn to them. In days of old they ruled as Kings of the Graph; since the Aggregate Store Conquest they have been Wardens of the Path. Their seat, San Mateo, is an ancient castle renowned for its sushi. Their sigil is a octopus racing across a field of white, and their words are “Neo4j 2.0 Is Coming,” one of only a few house mottoes to be a warning rather than a boast. Members of the family tend to be lean of build and long of face, with golden hair and blue eyes.

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Visualizing the news with Vivagraph.js

neo_news

Today I want to introduce you to VivaGraphJS – a JavaScript Graph Drawing Library made by Andrei Kashcha of Yasiv. It supports rendering graphs using WebGL, SVG or CSS formats and currently supports a force directed layout. The Library provides an API which tracks graph changes and reflect changes on the rendering surface which makes it fantastic for graph exploration.

Today we will be integrating it with Neo4j and the Alchemy API.

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Permission Resolution with Neo4j – Part 3

write_automated_test2

Let’s add a couple of performance tests to the mix. We learned about Gatling in a previous blog post, we’re going to use it here again. The first test will randomly choose users and documents (from the graph we created in part 2) and write the results to a file, the second test will re-use the results of the first one and run consistently so we can change hardware, change Neo4j parameters, tune the JVM, etc. and see how they affect our performance.

The full code for the Random Permissions test is here, I’ll just highlight the main parts:
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Neo4j and Gatling sitting in a tree, Performance T-E-S-T-ing

neo4j_loves_gatling

I was introduced to the open-source performance testing tool Gatling a few months ago by Dustin Barnes and fell in love with it. It has an easy to use DSL, and even though I don’t know a lick of Scala, I was able to figure out how to use it. It creates pretty awesome graphics and takes care of a lot of work for you behind the scenes. They have great documentation and a pretty active google group where newbies and questions are welcomed.

It ships with Scala, so all you need to do is create your tests and use a command line to execute it. I’ll show you how to do a few basic things, like test that you have everything working, then we’ll create nodes and relationships, and then query those nodes.
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Facebook Graph Search with Cypher and Neo4j

Update: Facebook has disabled this application

Your app is replicating core Facebook functionality.

neo_graph_search_screen_shot

Facebook Graph Search has given the Graph Database community a simpler way to explain what it is we do and why it matters. I wanted to drive the point home by building a proof of concept of how you could do this with Neo4j. However, I don’t have six months or much experience with NLP (natural language processing). What I do have is Cypher. Cypher is Neo4j’s graph language and it makes it easy to express what we are looking for in the graph. I needed a way to take “natural language” and create Cypher from it. This was going to be a problem.
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Extending Neo4j

One of the great things about Neo4j is how easy it is to extend it. You can extend Neo4j with Plugins and Unmanaged Extensions. Two great examples of plugins are the Gremlin Plugin (which lets you use the Gremlin library with Neo4j) and the Spatial Plugin (which lets you perform spatial operations like searching for data within specified regions or within a specified distance of a point of interest).

Plugins are meant to extend the capabilities of the database, nodes, or relationships. Unmanaged extensions are meant to let you do anything you want. This great power comes with great responsibility, so be careful what you do here. David Montag cooked up an unmanaged extension template for us to use on github so lets give it a whirl. We are going to clone the project, compile it, download Neo4j, configure Neo4j to use the extension, test the extension and tweak it a bit.
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