Category Archives: Cypher

Faux Bitmap Indexes in Neo4j

If you’ve ever watched my talks about Neo4j, I tend to say we’re not very well optimized for Single Model queries where relationships aren’t considered. In fact, we’re kinda bad at it. Things got better when Composite Indexes were introduced, but we still have some limitations to deal with. Today we’re going to explore the issues and build our own faux “bitmap indexes” to get around this problem.
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Finding Fraud Part Two Revised

A few months ago I wrote up how to use the graph algorithms library to find fraud rings in bank data. The graph algorithms plugin has been a huge hit and received a promotion to a fully supported library with a team of developers, data scientists and product managers behind it. It was partially rewritten and given a fresh name. It is now called the Graph Data Science Library.

We’re going to give that fraud blog post a fresh look as well, change it to use the new library as well as throw more data at it. Please be sure you go back and read the original post right now so it’s fresh in your mind what we are going to do. Make sure you have the latest version of Neo4j Desktop running ( at least version 1.2.5 ), create a new graph with version 3.5.15 and install the plugin:
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Composite Indexes in Neo4j 4.0

Neo4j 4.0 has officially launched and folks are very excited about some of the new features including multiple graphs and schema based security. But you should also be excited about some of the more “quality of life” improvements in the product. One we will talk about today is the upgrade that composite indexes received.

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Getting the latest transactions

On Neo4j’s User Slack someone was having a bit of a hard time getting a query to return quickly. Their model had User Nodes and Transaction Nodes, and they wanted to get the last 25 transactions for a user. This particular user had millions of transactions and the query was taking forever. I’m going to show you how we can speed up the query and hopefully teach you a new modeling trick you can use in your graphs.

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Visualizing Activities

A few weeks ago I blogged about Activities in Neo4j, and we ended up with a way to recommend an activity to a user based on what sequence of activities they had done in the past. We also had a list of common sequences of activities, but they were a bit hard to digest. Today I’m going to show you how to visualize them so they make more sense.

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Marketing Activities

The “footprints in the sand” poem is a story of a person walking on the beach with God and seeing two sets of footprints. The footprints represent the joys and sorrows of this persons life. During the worst of times the trail shows just one set of footprints. Confused as to why they would be abandoned at their time of need, God replies that “when you see only one set of footprints, it was then that I carried you”. It’s a touching poem, but a single set of footprints in the sand isn’t very graphy. Things get interesting when you superimpose the paths one over the other. We can then start to see where many paths converged and diverged, see how deep the footprints got at times, when they split where they went and where did they end up.
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The Real Property Graph

Is not that thing above. That’s a Chart, not a Graph. But anyway…Neo4j is designed to support the property graph model natively. There are a host of other technologies that can bolt-on a “graph layer” of some kind. However it doesn’t make them a graph database. It’s like adding a rear spoiler to a van, sure it may look cool… or ridiculous, but it won’t make it a race car. Don’t fall for it. If you need fast graph queries, use a real graph database. But today we won’t talk about that. Instead we’re going to talk about the real property graph…
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Finding Fraud Part Two

In the last blog post, we saw how we can use Neo4j to find the merchants where credit card fraud originated or was used for testing stolen data in order to prevent further fraudulent charges. It stemmed from a webinar on our amazing youtube channel with has hundreds of videos about graphs and Neo4j. We will continue diving in to the technical details by looking at how Neo4j can help you find Fraud Rings. The way this fraud works is that a large set of synthetic accounts are created and act like normal customers. Over time they request higher and higher levels of credit which they pay back on time. Then they all request the maximum credit they can get, take out the money, and disappear! Let’s find them before this happens.

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Finding Fraud

It’s no secret that one of our hottest use cases lately has been Fraud Detection. A while back we did a webinar talking about some of the ways you could use Neo4j to fight fraud. Watch it, if you haven’t yet. Today I want to augment that webinar with some cypher queries. Let’s see how it works:
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Parallel K-Hop Counts

As a foreigner I was a little perplexed the first time I went to IHOP. You are served a stack of pancakes 3-5 high. How do you eat them? Do you pour syrup over the top and cut down through all the layers and eat them that way… or do you unstack them, pour syrup over each one and eat one at a time? If you are American, you eat them stacked. If you see someone eat them one at a time, you know they are shape-shifting lizard people. But doesn’t that mean the bottom layers are dry and don’t get any butter or syrup on them? Well you would think, but Americans are an ingenious people and they found a way to fix that problem. More syrup, more and more, and then a bit more to be sure… and a side of bacon. Now that you know all about IHOP, let’s switch gears to KHOP. Let’s say you wanted to find out how many nodes there were k-hops away from a starting node. What would be the best way to do that?

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