software | Max De Marzi

Dec 27 2016

Connected

The Stereo MC’s song “Connected” could be about some recently gained insight and the realization that maybe some of the people you held dear are phonies and while the reality of the situation is scary, you cannot allow yourself to turn a blind eye anymore or allow yourself to backslide by disconnecting from the real world.

Or it could be a warning about how we’ve all been blinded by SQL databases for too long and we must instead look to connect our data with Graph Databases. About how those new connections may be scary (like because of fraud detection) but they are necessary to better understand reality.

Either way, we may want to see if two nodes in Neo4j are connected and I’m going to show you how to do that faster.
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Tagged big data, graph, graph database, graph databases, java, neo4j, performance, relationship graph, software, technology

Sep 28 2016

2 Comments

Java, Problems, Random

Delivering a Graph Based Search solution to slightly wrong data

When it comes to databases, having good clean data is always important. More so with Graphs which deal with concepts as nodes and their relationships between them. Inevitably, you will run into messy data and have to deal with it. In a lot of the projects our customers work on they are dealing with connecting multiple data sources to get to a “golden record” or single source of truth. A lofty goal, sometimes impossible to achieve, but we can use the relationships of the data to help us come close.

One option is to extract the features (or tags) of a composite object and see if any other object shares most of these features. If that is the case then they are possibly the same object and should be merged instead of creating a new record. A partial subgraph match is something akin to a recommendation engine in Neo4j and pretty trivial to write. Take a look back at a few old blog posts for ideas.
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Tagged big data, graph database, graph search, java, neo4j, network, performance, relationship graph, search, software, technology

Nov 20 2015

1 Comment

Java, Problems

Bidirectional Traversals in Space

If you have never watched Firefly, then stop whatever you are doing and get to it, you can come back and read this post later. Ok good, now where were we. Firefly. The series is set a few hundred years from now, after people begin to terraform a new star system and it follows the adventures of the renegade crew of Serenity, a “Firefly-class” spaceship whose work consists of cargo runs or smuggling while failing to stay out of trouble. There is no faster than light travel in this series, so ships can’t just “warp” where ever they want. Instead they travel about from planets and moons, exchanging cargo, refueling and trying to make a living. We are going to model “The Verse” of Firefly in Neo4j, and see how we can find routes to move our illicit cargo from one place to another.
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Tagged firefly, github, graph database, java, neo4j, network, software, space, technology, transportation

Sep 04 2015

7 Comments

Java, Problems

Flight Search with the Neo4j Traversal API

Before Cypher came along, if you wanted to describe a graph traversal in Neo4j you would use the Traversal Framework Java API. The Traversal API is one of the many hidden gems of Neo4j and today we are going to take a closer look at it. Traversing a graph is about going on a journey. All journeys have a starting point (or points) so that’s the first thing we have to do, figure out where in the graph we begin. It can be a single node, or multiple ones, but they will go on the journey following the same rules, so its easier if it’s just one node or nodes of the same “type”.
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Tagged cypher, github, graph database, java, neo4j, network, nosql, relationship, software, technology

Apr 14 2015

2 Comments

Cypher, Problems, Random

Importing the Hacker News Interest Graph

Graphs are everywhere. Think about the computer networks that allow you to read this sentence, the road or train networks that get you to work, the social network that surrounds you and the interest graph that holds your attention. Everywhere you look, graphs. If you manage to look somewhere and you don’t see a graph, then you may be looking at an opportunity to build one. Today we are going to do just that. We are going to make use of the new Neo4j Import tool to build a graph of the things that interest Hacker News.
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Tagged cypher, graph database, graph databases, hacker news, hcir, interest graph, neo4j, network, nosql, relationship graph, ruby, software, technology

Mar 17 2015

6 Comments

Cypher, Java, Problems

One Direction Relationships in Neo4j

In the Neo4j Property Graph model, every single Relationship must be Typed and Directed. This means they must have a specific name (FRIENDS, LIKES, FOLLOWS, etc) and have a Start Node and an End Node to show direction. What’s neat is that when you write your queries you can choose to ignore that. The following queries are all valid:

// Get all the people I follow 
MATCH (u1:Person)-[:FOLLOWS]->(u2:Person)
WHERE u1.username = "maxdemarzi"
RETURN u2.username

// Get all the people that I follow or follow me
MATCH (u1:Person)-[:FOLLOWS]-(u2:Person)
WHERE u1.username = "maxdemarzi"
RETURN u2.username

// Get all the people related to me 
MATCH (u1:Person)--(u2:Person)
WHERE u1.username = "maxdemarzi"
RETURN u2.username

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Tagged graph database, java, neo4j, performance, software, technology

Mar 08 2015

Giving Neo4j 2.2 a Workout

Neo4j 2.2 is getting released any day now, so let’s put the Release Candidate through its paces with Gatling. Once we download and start it up, you’ll notice it wants us to authenticate.
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Tagged cypher, gatling, graph database, neo4j, network, performance, software, technology, testing

Apr 24 2014

2 Comments

Cypher, Java, Problems

Translating Cypher To Neo4j Java API 2.0

About 6 months ago we looked at how to translate a few lines of Cypher in to way too much Java code in version 1.9.x. Since then Cypher has changed and I suck a little less at Java, so I wanted to share a few different ways to translate one into the other just in case you stuck in a mid-eighties time warp and are paid by the number of lines of code you write per hour.

But first, ~~lemme take a #Selfie~~ let’s make some data. Michael Hunger has a series of blog posts on getting and creating data in Neo4j, we’ll ~~steal~~ borrow his ideas. Let’s create 100k nodes:

WITH ["Jennifer","Michelle","Tanya","Julie","Christie","Sophie","Amanda","Khloe","Sarah","Kaylee"] AS names 
FOREACH (r IN range(0,100000) | CREATE (:User {username:names[r % size(names)]+r}))

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Tagged cypher, graph, graph database, java, neo4j, performance, profile, relationship graph, software, technology, testing, yourkit

Apr 01 2014

Neo4j all the way Down!

ext_inside_server_inside_embedded

Just because you can, doesn’t mean you should. However sometimes it can be comforting to know how. I am going to show you how to run Neo4j Embedded and Neo4j Server at the same time…and an Unmanaged Extension inside that Neo4j Server. There aren’t any real good reasons why you’d want to do this, but it’s April Fools, so here we go.

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Tagged graph, graph database, java, neo4j, software, Undertow

Mar 10 2014

4 Comments

Deployment, Java, Problems

It’s over 9000! Neo4j on WebSockets

In the last blog post we managed to run Neo4j at Ludicrous Speed over http using Undertow and get to about 8000 requests per second. If we needed more speed we can scale up the server or we can scale out to multiple servers by switching out the GraphDatabaseFactory and using the HighlyAvailableGraphDatabaseFactory class instead in Neo4j Enterprise Edition.

But can we go faster on a single server without new hardware? Well… yes, if we’re willing to drop http and switch to Web Sockets.

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Tagged github, graph, graph database, neo4j, performance, software, technology, testing, Undertow

Max De Marzi

Graphs, Graphs, and nothing but the Graphs

Tag Archives: software

Connected

Delivering a Graph Based Search solution to slightly wrong data

Bidirectional Traversals in Space

Flight Search with the Neo4j Traversal API

Importing the Hacker News Interest Graph

One Direction Relationships in Neo4j

Giving Neo4j 2.2 a Workout

Translating Cypher To Neo4j Java API 2.0

Neo4j all the way Down!

It’s over 9000! Neo4j on WebSockets