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Max De Marzi, is a seasoned web developer. He started building websites in 1996 and has worked with Ruby on Rails since 2006. The web forced Max to wear many hats and master a wide range of technologies. He can be a system admin, database developer, graphic designer, back-end engineer and data scientist in the course of one afternoon. Max is a graph database enthusiast. He built the Neography Ruby Gem, a rest api wrapper to the Neo4j Graph Database. He is addicted to learning new things, loves a challenge and finding pragmatic solutions. Max is very easy to work with, focuses under pressure and has the patience of a rock. Max is a DZone MVB and is not an employee of DZone and has posted 60 posts at DZone. You can read more from them at their website. View Full User Profile

Neo4j Internals

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An overview of Neo4j Internals View more presentations from Tobias Lindaaker

It is interesting to see how node, relationship and property records are stored differently on disk and in the cache.

It is all linked lists of fixed size records on disk. Properties are stored as a linked list of property records, each holding a key and value and pointing to the next property. Each node and relationship references its first property record. The Nodes also reference the first relationship in its relationship chain. Each Relationship references its start and end node. It also references the previous and next relationship record for the start and end node respectively.

On disk most of the information is contained in the relationship records, with the nodes just referencing their first relationship. In the Node cache this is turned around: the nodes hold references to all of its relationships. The relationships are simple, only holding its properties. The relationships for each node is grouped by RelationshipType to allow fast traversal of a specific type. All references (dotted arrows) are by ID, and traversals do indirect lookup through the cache.

View a video presentation of these slides on Skill Matter.

Published at DZone with permission of Max De Marzi, author and DZone MVB. (source)

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