orientdb document or graph? select the right model (old presentation)

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

Select the right model

„Document vs Graph,

what is the answer?“

Document rev 1.1

http://creativecommons.org/licenses/by-nd/3.0/




OrientDB supports multiple models

Document

Graph

Custom Graph*

*available in 1.2





What is the best choice for my domain?





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





This is the reason why

even using the Document model

you can manage complex graphs

of objects





Relationships





Graph Model Vertex & Edges I

Vertex A

Vertex B

out

in

Connections using bidirectional Edges





Vertex A

Vertex B

out

in

Edge A-B

Graph Model Vertex & Edges II

Edges in OrientDB are records with own RecordID of class

«OGraphEdge» or just «E» as alias.





Vertex A

Vertex B

in

Edge A-B

Graph Model Vertex & Edges III

out*

* in out

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





Graph Model summary

connect vertices using edges

A vertex has "in" for the incoming

relationships and "out" for the outgoing

relationships

are always bidirectional





Document Model oneway direct connections

Professor Jay

Student Steve

students *

Connections are directed without using Edges and are always

monodirectional





Document Model express the cardinality

City Palo Alto

city 1

City = 1 Using LINK type

Professor Jay

Student Steve

students *

Students = N Using LINKSET type





Document Model express the cardinality

Professor Jay

Student Steve

students *

Use LINKSET or LINKMAP for unordered collection doesn’t accept duplicates, otherwise

LINKLIST as ordered with duplicated





Document Model bidirectional connections

Professor Jay

Student Steve

students *

professors *

To create bidirectional links create 2 relationships:

1. from Professor to Student 2. from Student to Professor





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





Graph Model vs

Document Model





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





Graph Model CONS

1. Edges are record themselves, so db is bigger: one

record more per edge

2. Traversing between Vertices needs to load the

Edge record too, so it‘s slower

3. All the outgoing relationships are inside the "out"

collection: worst performance in case you have

connections of different kind





Document Model PROS

1. Lighter than Graph Model, no need for a separate

record to manage relationships

2. Faster on traversing because links are directing

bypassing the Edge records

3. Finer grained cardinality setting also the

relationship type





Document Model CONS

1. Cannot use the GREMLIN and full TinkerPop

Blueprints stack

2. No native bidirectional connection, so the

application has to manage the double connection

3. Edges cannot have properties





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





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.





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





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





NuvolaBase.com

The first

Graph Database

on the Cloud

always available

few seconds to setup it

use it from Web & Mobile

apps





Luca Garulli

www.twitter.com/lgarulli

CEO at

Ltd, London UK

Author of

Document-Graph NoSQL Open Source project




orientdb document or graph? select the right model (old presentation)

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