It Depends (and why it's the most frequent answer to modelling questions)
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The answer to most general purpose graph modelling questions is "it depends". This talk demonstrates the pitfalls of modelling without knowing use cases- it shows how two sets of people can produce two different models for the same set of data elements, and how use cases should guide the model. About the speaker: Luanne Misquitta is VP of Engineering at GraphAware, and has been working with Neo4j for 10+ years. She was a core committer to Neo4j OGM and SDN 4, has spoken at GraphConnect in both Europe and the US. NODES 2019 - Neo4j Online Developer Expo & Summit - 10th October 2019
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It Depends (and why it's the most frequent answer to modelling questions)
- 1. GraphAware® It Depends… Luanne Misquitta VP of Engineering graphaware.com @graph_aware, @luannem and why it’s the most frequent answer to graph modelling questions
- 2. The Data GraphAware® ‣ Movies ‣ Actors ‣ Directors ‣ Roles ‣ Genres
- 4. Candidate Graph Model 1 GraphAware® Person name ACTED_IN DIRECTED roles:[“role1”,”role2”] Movie title genre
- 5. Candidate Graph Model 2 GraphAware® Person name Movie title ACTED_IN DIRECTED roles:[“role1”,”role2”] Genre name HAS_GENRE
- 6. Candidate Graph Model 3 GraphAware® Person name Movie [Genre] title ACTED_IN DIRECTED roles:[“role1”,”role2”]
- 7. Candidate Graph Model 4 GraphAware® Person name Movie title Genre name Role name HAS_GENRE PLAYED_ROLE ROLE ROLE_IN_MOVIE DIRECTED
- 8. GraphAware®
- 9. Don’t be afraid! GraphAware® ‣ Graph modelling is an extremely useful exercise ‣ Validate your understanding of the problem on a whiteboard ‣ The way you naturally represent your domain on the whiteboard is generally your graph model ‣ No normalisation rules required- all stakeholders can participate ‣ Expose gaps in thinking, missing data early ‣ This modelling is beneficial even if you’re not using a graph database ‣ But if you draw it as a graph, and think of it as a graph, you probably need a graph database
- 11. Now what? GraphAware® ‣ Should role be ‣ a property on a relationship? ‣ a node?
- 12. Now what? GraphAware® ‣ Should genre be ‣ a property on a node? ‣ a node? ‣ a label? ‣ both?
- 15. What is the question? GraphAware® ‣ The use case or the question you’re asking of the graph will determine the most suitable graph model to ‣ Answer the question ‣ Perform efficient queries ‣ Keep things simple- model just enough, but no more
- 16. ‣ As a movie fan, I want to find a movie, and see actors and their roles Use case #1 GraphAware®
- 17. ‣ As a movie fan, I want to find a movie, and see actors and their roles Use case #1 GraphAware® Person name Movie title genre ACTED_IN DIRECTED roles:[“role1”,”role2”]
- 18. ‣ As a movie fan, I want to find movies in genres similar to my favourites Use case #2 GraphAware®
- 19. ‣ As a movie fan, I want to find movies in genres similar to my favourites Use case #2 GraphAware® Person name Movie title ACTED_IN DIRECTED roles:[“role1”,”role2”] Genre name HAS_GENRE Movie title Genre name ACTED_IN HAS_GENRE SIMILAR_TO
- 20. ‣ As a movie fan, I want to find actors who played the role of Neo and the awards they won for this role Use case #3 GraphAware®
- 21. ‣ As a movie fan, I want to find actors who played the role of Neo and the awards they won for this role Use case #3 GraphAware® Person name Movie title DIRECTED Genre name HAS_GENRE Movie title Genre name ACTED_IN HAS_GENRE SIMILAR_TO Role name <hyperedge> Award name PLAYED_ROLE AWARD_ROLE ROLE ROLE_IN_MOVIEYear
- 22. Summary GraphAware® ‣ Know thy use case ‣ Keep it simple and intuitive ‣ Consider ‣ the shape and size of your data ‣ the density of relationships ‣ selectivity ‣ read vs write trade-offs ‣ Measure performance but… ‣ Do not prematurely optimise- graph model refactoring is easy!
- 23. Hunger Games GraphAware® 1. Easy: To be able to model your graph well, you should know A. Your use case B. The weather C. A list of hair-metal bands 2. Medium: Should I model this fact as a property of a node, or a node? A. Property of a node B. A node C. It depends 3. Hard: Sometimes you need an edge that relates more than 2 nodes. What do you do? A. Use a relationship between two nodes, store the context as properties B. Use a hyper edge C. Model with multiple nodes but identify they belong together with a groupID Answer at: r.neo4j.com/hunger-games