OrientDB document or graph? Select the right model

Document rev 1.1 Select the right model „Document vs Graph, what is the answer?“© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 1

OrientDB supports multiple models Document Graph Custom Graph* *available in 1.2© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 2

What is the best choice for my domain?© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 3

Facts Graph Model has been built on top of the Document Model But why it is so fast? Because in OrientDB relationships are direct links, not relational JOINs© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 4

This is the reason why even using the Document model you can manage complex graphs of objects© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 5

Relationships© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 6

Graph Model Vertex & Edges I in Vertex Vertex A B out Connections using bidirectional Edges© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 7

Graph Model Vertex & Edges II in Vertex Vertex Edge A-B A B out Edges in OrientDB are records with own RecordID of class «OGraphEdge» or just «E» as alias.© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 8

Graph Model Vertex & Edges III out* in Vertex Vertex Edge A-B A B out * in To access to the ougoing vertices use «out.in» because: 1. Vertex A exits through «out» to go to the 2. Edge, and then 3. «in» to arrive to the Vertex B© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 9

Graph Model summary connect vertices using edges A vertex has "in" for the incoming relationships and "out" for the outgoing relationships are always bidirectional© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 10

Document Model oneway direct connections students * Professor Student Jay Steve Connections are directed without using Edges and are always monodirectional© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 11

Document Model express the cardinality students * Professor Student Jay Steve Students = N Using LINKSET type city 1 City Palo Alto City = 1 Using LINK type© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 12

Document Model express the cardinality students * Professor Student Jay Steve Use LINKSET or LINKMAP for unordered collection doesn’t accept duplicates, otherwise LINKLIST as ordered with duplicated© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 13

Document Model bidirectional connections students * Professor Student Jay Steve professors * To create bidirectional links create 2 relationships: 1. from Professor to Student 2. from Student to Professor© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 14

Document Model summary Connections are always as oneway, to have a bidirectional relationship create 2 connections Single cardinality: LINK Multiple cardinality: LINKSET and LINKMAP for unordered, no duplicates and LINKLIST: ordered allows duplicates© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 15

Graph Model vs Document Model© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 16

Graph Model PROS 1. Ability to use GREMLIN and full TinkerPop Blueprints stack 2. Connections are always bidirectional: leave open the ability to move in all the directions even is not planned at the beginning 3. Edges can have properties© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 17

Graph Model CONS1. Edges are record themselves, so db is bigger: one record more per edge2. Traversing between Vertices needs to load the Edge record too, so it‘s slower3. All the outgoing relationships are inside the "out" collection: worst performance in case you have connections of different kind© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 18

Document Model PROS1. Lighter than Graph Model, no need for a separate record to manage relationships2. Faster on traversing because links are directing bypassing the Edge records3. Finer grained cardinality setting also the relationship type© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 19

Document Model CONS1. Cannot use the GREMLIN and full TinkerPop Blueprints stack2. No native bidirectional connection, so the application has to manage the double connection3. Edges cannot have properties© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 20

Suggestions What to use? Graph and Document models have PROS and CONS. Often it‘s hard to select the right one because there couldn‘t be a right one. The next use cases are very generics so don‘t take them as rule of the thumb© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 21

Suggestions (1) Social Applications Highly suggested the Graph Model because you‘re always ready to analyze the graph in any direction using advanced tools like GREMLIN language. Graph algorithm already developed through TinkerPop stack like Shortest Path, Ranking, etc.© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 22

Suggestions (2) CRM/Business Applications You could select both. Here the Document Model is a good candidate because relationships don‘t change so often and are mostly known at the beginning© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 23

Suggestions (3) Highest performance Since the Graph Model is heavier because requires more records and more traverse time, the suggested here is the Document Model© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 24

NuvolaBase.com The first Graph Database on the Cloud always available few seconds to setup it use it from Web & Mobile apps© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 26

Luca Garulli Author of CEO at Document-Graph NoSQL Open Source project Ltd, London UK www.twitter.com/lgarulli© Luca Garulli - 2012 Licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License Page 27

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OrientDB document or graph? Select the right model

by Luca Garulli on Jun 25, 2012

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