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Tag Archives: Neo4j

Neo4j: Generic/Vague relationship names

An approach to modelling that I often see while working with Neo4j users is creating very generic relationships (e.g. HAS, CONTAINS, IS) and filtering on a relationship property or on a property/label at the end node. Intuitively this doesn’t seem to make best use of the graph model as it means that you have to evaluate many relationships and nodes ...

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Neo4j: COLLECTing multiple values

One of my favourite functions in Neo4j’s cypher query language is COLLECT which allows us to group items into an array for later consumption. However, I’ve noticed that people sometimes have trouble working out how to collect multiple items with COLLECT and struggle to find a way to do so. Consider the following data set:         create ...

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Integrate apps with Neo4j using Zapier

Recently, I was directed to Zapier to get some lightweight integration done between systems for a quick proof of concept. Initially skeptical, I found that it really could save time and tie together all those pieces of your system you never got around to integrating. Moreover, it is a way for people to integrate the applications they use without having ...

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On Graph Computing

The concept of a graph has been around since the dawn of mechanical computing and for many decades prior in the domain of pure mathematics. Due in large part to this golden age of databases, graphs are becoming increasingly popular in software engineering. Graph databases provide a way to persist and process graph data. However, the graph database is not ...

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Knowledge Representation and Reasoning with Graph Databases

A graph database and its ecosystem of technologies can yield elegant, efficient solutions to problems in knowledge representation and reasoning. To get a taste of this argument, we must first understand what a graph is. A graph is a data structure. There are numerous types of graph data structures, but for the purpose of this post, we will focus on ...

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Neo4j 2.1: Passing around node ids vs UNWIND

When Neo4j 2.1 is released we’ll have the UNWIND clause which makes working with collections of things easier. In my blog post about creating adjacency matrices we wanted to show how many people were members of the first 5 meetup groups ordered alphabetically and then check how many were members of each of the other groups.         ...

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Neo4j Backup: Store copy and consistency check at Mark Needham

One of the lesser known things about the Neo4j online backup tool, which I wrote about last week, is that conceptually there are two parts to it: Copying the store files to a location of your choice Verifying that those store files are consistent. By default both of these run when you run the ‘neo4j-backup’ script but sometimes it’s useful ...

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Java: Schedule a job to run on a time interval

Recently I’ve spent some time building a set of tests around rolling upgrades between Neo4j versions and as part of that I wanted to log the state of the cluster as the upgrade was happening. The main thread of the test blocks waiting until the upgrade is done so I wanted to log on another thread every few seconds. Alistair ...

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