One of the often overlooked features in Neo4j is the “TransactionEventHandler” capabilities… better known in the database world as “Triggers“. When a transaction occurs, we can analyze that event and decide to take some action. To accomplish this, we’ll write a “Kernel Extension” ( a little different from the Unmanaged Extensions we’ve seen on this blog ) to tie in our trigger.
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
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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If you’ve been following my blog for a while, you probably know I like using YourKit and Gatling for testing end to end requests in Neo4j. Today however we are going to do something a little different. We are going to be micro-benchmarking a very small piece of code within our Unmanaged Extension using a Java library called JMH.
A few months ago, Mark Needham blogged about how to setup remote monitoring of Neo4j using YourKit. I was asked the other day about getting a few more details on how to do this on Amazon, so here is my attempt at that. The first thing we’ll do is setup Neo4j on a Virtual Private Cloud. It’s good practice to not put your databases directly on the public internet.
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I started my software development career writing applications for a Call Center at a small bank in Florida. I remember the bank had purchased whatever the “Cadillac” of Interactive Voice Response (IVR) systems was then for some crazy amount of money. Today you can build an IVR overnight using Twilio.
When you sign up with Twilio, you get to choose your phone number (more or less). For example, I picked +1 (636) 451-7411, which spells out +1 (neo) 4j1-7411. If you were to call this number right now (assuming I have not run out of Twilio credits) you’ll connect to my IVR.
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A while ago, I showed you a way to scale Neo4j writes using RabbitMQ. Which was kinda cool, but some of you asked me for a different solution that didn’t involve adding yet another software component to the stack.
Turns out we can do this in just Neo4j using a little help from the Guava library. The solution involved a background service running that holds the writes in a queue, and every once in a while (like say every second) commits those writes in one transaction.
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Learn how to build high performance @neo4j applications with this video training course.
I’m on Kickstarter to ask for your help in order to create a set of videos to teach you how to build high performance Neo4j applications. I am going to capture the lessons I’ve learned over the past 4 years working with graph databases and share them with you.
These videos will teach you everything you need to know about building high performance applications using Neo4j.
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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}))
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.
