nosqleu - graph databases and neo4j
DESCRIPTION
Presentation about Neo4j from NOSQLEU 2010 ( http://nosqleu.com/ ).TRANSCRIPT
Graph Databasesand Neo4j
Tobias IvarssonHacker @ Neo Technology
twitter: @thobe / #neo4jemail: [email protected]: http://www.neo4j.org/web: http://www.thobe.org/
2006 2007 2008 2009 2010
0
250
500
750
1000
161253
397
623
988ExaBytes (10¹⁸) of data stored per year
3
Trend 1: Data size
Data source: IDC 2007
Each year more and more digital data is created. Over two years we create more digital data than all the data created in history before that.
Trend 2: Connectedness
4
Text documents
1990
Info
rmat
ion
conn
ectiv
ity Folksonomies
Tagging
User-generated content
Wikis
RSS
Blogs
Hypertext
2000 2010 2020
web 1.0 web 2.0 “web 3.0”
Ontologies
RDF
GiantGlobal
Graph (GGG)
Over time data has evolved to be more and more interlinked and connected.Hypertext has links,Blogs have pingback,Tagging groups all related data
Trend 3: Semi-structure
5
๏ Individualization of content
• In the salary lists of the 1970s, all elements had exactly one job
• In the salary lists of the 2000s, we need 5 job columns! Or 8? Or 15?
๏All encompassing “entire world views”
• Store more data about each entity
๏Trend accelerated by the decentralization of content generation that is the hallmark of the age of participation (“web 2.0”)
DBDB DB
Trend 4: Architecture
8
Application
2000s: (moving towards) Decoupled serviceswith their own backend
Application Application
Why NOSQL Now?
๏Trend 1: Size
๏Trend 2: Connectedness
๏Trend 3: Semi-structure
๏Trend 4: Architecture
9
RDBMS performance
10Data complexity
Perfo
rman
ce
Majority ofWebapps
Social network
Semantic Trading
Salary List
}custom
Relational database
Requirement of application
We are building applications today that have complexity requirements that a Relational Database cannot handle with sufficient performance
Scaling to size vs. Scaling to complexity
11
Size
Complexity
Key/Value stores
Bigtable clones
Document databases
Graph databases
> 90% of use cases
Billions of nodesand relationships
12
Graph Databases focuses on structure of data
Graph databases focus on the structure of the data, scaling to the complexity of the data and of the application.
What is Neo4j?๏Neo4j is a Graph Database
•Non-relational (“#nosql”), transactional (ACID), embedded
•Data is stored as a Graph / Network
‣Nodes and relationships with properties
‣“Property Graph” or “edge-labeled multidigraph”
• Schema free, bottom-up data model design
๏Neo4j is Open Source / Free (as in speech) Software
•AGPLv3
•Commercial (“dual license”) license available
‣First server is free (as in beer), next is inexpensive 13
Prices are available at http://neotechnology.com/
Contact us if you have questions and/or special license needs (e.g. if you want an evaluation license)
More about Neo4j๏Neo4j is stable
• In 24/7 operation since 2003
๏Neo4j is in active development
•Neo Technology received VC funding October 2009
๏Neo4j delivers high performance graph operations
• traverses 1’000’000+ relationships / secondon commodity hardware
14
The Neo4j Graph data model
15
•Nodes•Relationships between Nodes•Relationships have Labels•Relationships are directed, but traversed at equal speed in both directions•The semantics of the direction is up to the application (LIVES WITH is reflexive, LOVES is not)•Nodes have key-value properties•Relationships have key-value properties
The Neo4j Graph data model
15
•Nodes•Relationships between Nodes•Relationships have Labels•Relationships are directed, but traversed at equal speed in both directions•The semantics of the direction is up to the application (LIVES WITH is reflexive, LOVES is not)•Nodes have key-value properties•Relationships have key-value properties
The Neo4j Graph data model
15
LIVES WITHLOVES
OWNSDRIVES
•Nodes•Relationships between Nodes•Relationships have Labels•Relationships are directed, but traversed at equal speed in both directions•The semantics of the direction is up to the application (LIVES WITH is reflexive, LOVES is not)•Nodes have key-value properties•Relationships have key-value properties
The Neo4j Graph data model
15
LIVES WITHLOVES
OWNSDRIVES
LOVES
•Nodes•Relationships between Nodes•Relationships have Labels•Relationships are directed, but traversed at equal speed in both directions•The semantics of the direction is up to the application (LIVES WITH is reflexive, LOVES is not)•Nodes have key-value properties•Relationships have key-value properties
The Neo4j Graph data model
15
LIVES WITHLOVES
OWNSDRIVES
LOVESname: “James”age: 32twitter: “@spam”
name: “Mary”age: 35
brand: “Volvo”model: “V70”
•Nodes•Relationships between Nodes•Relationships have Labels•Relationships are directed, but traversed at equal speed in both directions•The semantics of the direction is up to the application (LIVES WITH is reflexive, LOVES is not)•Nodes have key-value properties•Relationships have key-value properties
The Neo4j Graph data model
15
LIVES WITHLOVES
OWNSDRIVES
LOVESname: “James”age: 32twitter: “@spam”
name: “Mary”age: 35
brand: “Volvo”model: “V70”
item type: “car”
•Nodes•Relationships between Nodes•Relationships have Labels•Relationships are directed, but traversed at equal speed in both directions•The semantics of the direction is up to the application (LIVES WITH is reflexive, LOVES is not)•Nodes have key-value properties•Relationships have key-value properties
Graphs are all around us
A B C D ...
1
2
3
4
5
...
17 3.14 3 17.79333333333
42 10.11 14 30.33
316 6.66 1 2104.56
32 9.11 592 0.492432432432
2153.175765766
16
Even if this spreadsheet looks like it could be a fit for a RDBMS it isn’t:•RDBMSes have problems with extending indefinitely on both rows and columns•Formulas and data dependencies would quickly lead to heavy join operations
Graphs are all around us
17
A B C D ...
1
2
3
4
5
...
17 3.14 3 = A1 * B1 / C1
42 10.11 14 = A2 * B2 / C2
316 6.66 1 = A3 * B3 / C3
32 9.11 592 = A4 * B4 / C4
= SUM(D2:D5)
With data dependencies the spread sheet turns out to be a graph.
Graphs are all around us
17
A B C D ...
1
2
3
4
5
...
17 3.14 3 = A1 * B1 / C1
42 10.11 14 = A2 * B2 / C2
316 6.66 1 = A3 * B3 / C3
32 9.11 592 = A4 * B4 / C4
= SUM(D2:D5)
With data dependencies the spread sheet turns out to be a graph.
Graphs are all around us
18
17 3.14 3 = A1 * B1 / C1
42 10.11 14 = A2 * B2 / C2
316 6.66 1 = A3 * B3 / C3
32 9.11 592 = A4 * B4 / C4
= SUM(D2:D5)
If we add external data sources the problem becomes even more interesting...
Graphs are all around us
18
17 3.14 3 = A1 * B1 / C1
42 10.11 14 = A2 * B2 / C2
316 6.66 1 = A3 * B3 / C3
32 9.11 592 = A4 * B4 / C4
= SUM(D2:D5)
If we add external data sources the problem becomes even more interesting...
Graphs are whiteboard friendly
19Image credits: Tobias Ivarsson
An application domain model outlined on a whiteboard or piece of paper would be translated to an ER-diagram, then normalized to fit a Relational Database.With a Graph Database the model from the whiteboard is implemented directly.
Graphs are whiteboard friendly
19
1
*
1
*
*
1*
1
*
*
Image credits: Tobias Ivarsson
An application domain model outlined on a whiteboard or piece of paper would be translated to an ER-diagram, then normalized to fit a Relational Database.With a Graph Database the model from the whiteboard is implemented directly.
Graphs are whiteboard friendly
19
thobe
Wardrobe Strength
Joe project blog
Image credits: Tobias Ivarsson
An application domain model outlined on a whiteboard or piece of paper would be translated to an ER-diagram, then normalized to fit a Relational Database.With a Graph Database the model from the whiteboard is implemented directly.
Hello Joe
Neo4j performance analysis
Modularizing Jython
Query Languages๏Traversal APIs
•Neo4j core traversers
•Blueprint pipes
๏SPARQL - “SQL for linked data” - query by graph pattern matching
SELECT ?person WHERE {?person neo4j:KNOWS ?friend .?friend neo4j:KNOWS ?foe .?foe neo4j:name "Larry Ellison" .
}
๏Gremlin - “perl for graphs” - query by traversal
./outE[@label='KNOWS']/inV[@age > 30]/@name
20
Find all persons that KNOWS a friend that KNOWS someone named “Larry Ellison”.
Give me the names of all the people I know that are older than 30.
Data manipulation APIGraphDatabaseService graphDb = getGraphDbInstanceSomehow();
// Create Thomas 'Neo' AndersonNode mrAnderson = graphDb.createNode();mrAnderson.setProperty( "name", "Thomas Anderson" );mrAnderson.setProperty( "age", 29 );
// Create MorpheusNode morpheus = graphDb.createNode();morpheus.setProperty( "name", "Morpheus" );morpheus.setProperty( "rank", "Captain" );morpheus.setProperty( "occupation", "Total bad ass" );
// Create relationship representing they know each othermrAnderson.createRelationshipTo( morpheus, RelTypes.KNOWS );// ... similarly for Trinity, Cypher, Agent Smith, Architect
21
Data manipulation APIGraphDatabaseService graphDb = getGraphDbInstanceSomehow();
// Create Thomas 'Neo' AndersonNode mrAnderson = graphDb.createNode();mrAnderson.setProperty( "name", "Thomas Anderson" );mrAnderson.setProperty( "age", 29 );
// Create MorpheusNode morpheus = graphDb.createNode();morpheus.setProperty( "name", "Morpheus" );morpheus.setProperty( "rank", "Captain" );morpheus.setProperty( "occupation", "Total bad ass" );
// Create relationship representing they know each othermrAnderson.createRelationshipTo( morpheus, RelTypes.KNOWS );// ... similarly for Trinity, Cypher, Agent Smith, Architect
21
Transaction tx = graphDb.beginTx();try {
tx.success();} finally {
tx.finish();}
since: “meeting the oracle” since: “a year before the movie”cooperates on: “The Nebuchadnezzar”
Graph traversals
22
name: “Thomas Anderson”age: 29
name: “Morpheus”rank: “Captain”occupation: “Total badass”
name: “Trinity”
name: “Cypher”last name: “Reagan”
name: “Agent Smith”version: “1.0b”language: “C++”
name: “The Architect”
KNOWS
KNOWS
KNOWSKNOWS
KNOWSCODED BY
LOVES
disclosure: “secret”
disclosure: “public”
since: “meeting the oracle” since: “a year before the movie”cooperates on: “The Nebuchadnezzar”
Graph traversals
import neo4jclass Friends(neo4j.Traversal): # Traversals ! queries in Neo4j
types = [ neo4j.Outgoing.KNOWS ]order = neo4j.BREADTH_FIRSTstop = neo4j.STOP_AT_END_OF_GRAPHreturnable = neo4j.RETURN_ALL_BUT_START_NODE
23
name: “Thomas Anderson”age: 29
name: “Morpheus”rank: “Captain”occupation: “Total badass”
name: “Trinity”
name: “Cypher”last name: “Reagan”
name: “Agent Smith”version: “1.0b”language: “C++”
name: “The Architect”
KNOWS
KNOWS
KNOWSKNOWS
KNOWSCODED BY
LOVES
disclosure: “secret”
disclosure: “public”
for friend_node in Friends(mr_anderson):print "%s (@ depth=%s)" % ( friend_node["name"],
friend_node.depth )
since: “meeting the oracle” since: “a year before the movie”cooperates on: “The Nebuchadnezzar”
Graph traversals
import neo4jclass Friends(neo4j.Traversal): # Traversals ! queries in Neo4j
types = [ neo4j.Outgoing.KNOWS ]order = neo4j.BREADTH_FIRSTstop = neo4j.STOP_AT_END_OF_GRAPHreturnable = neo4j.RETURN_ALL_BUT_START_NODE
23
name: “Thomas Anderson”age: 29
name: “Morpheus”rank: “Captain”occupation: “Total badass”
name: “Trinity”
name: “Cypher”last name: “Reagan”
name: “Agent Smith”version: “1.0b”language: “C++”
name: “The Architect”
KNOWS
KNOWS
KNOWSKNOWS
KNOWSCODED BY
LOVES
disclosure: “secret”
disclosure: “public”
for friend_node in Friends(mr_anderson):print "%s (@ depth=%s)" % ( friend_node["name"],
friend_node.depth )
since: “meeting the oracle” since: “a year before the movie”cooperates on: “The Nebuchadnezzar”
Graph traversals
import neo4jclass Friends(neo4j.Traversal): # Traversals ! queries in Neo4j
types = [ neo4j.Outgoing.KNOWS ]order = neo4j.BREADTH_FIRSTstop = neo4j.STOP_AT_END_OF_GRAPHreturnable = neo4j.RETURN_ALL_BUT_START_NODE
23
name: “Thomas Anderson”age: 29
name: “Morpheus”rank: “Captain”occupation: “Total badass”
name: “Trinity”
name: “Cypher”last name: “Reagan”
name: “Agent Smith”version: “1.0b”language: “C++”
name: “The Architect”
KNOWS
KNOWS
KNOWSKNOWS
KNOWSCODED BY
LOVES
disclosure: “secret”
disclosure: “public”
Morpheus (@ depth=1)
for friend_node in Friends(mr_anderson):print "%s (@ depth=%s)" % ( friend_node["name"],
friend_node.depth )
since: “meeting the oracle” since: “a year before the movie”cooperates on: “The Nebuchadnezzar”
Graph traversals
import neo4jclass Friends(neo4j.Traversal): # Traversals ! queries in Neo4j
types = [ neo4j.Outgoing.KNOWS ]order = neo4j.BREADTH_FIRSTstop = neo4j.STOP_AT_END_OF_GRAPHreturnable = neo4j.RETURN_ALL_BUT_START_NODE
23
name: “Thomas Anderson”age: 29
name: “Morpheus”rank: “Captain”occupation: “Total badass”
name: “Trinity”
name: “Cypher”last name: “Reagan”
name: “Agent Smith”version: “1.0b”language: “C++”
name: “The Architect”
KNOWS
KNOWS
KNOWSKNOWS
KNOWSCODED BY
LOVES
disclosure: “secret”
disclosure: “public”
Morpheus (@ depth=1)
Trinity (@ depth=1)
for friend_node in Friends(mr_anderson):print "%s (@ depth=%s)" % ( friend_node["name"],
friend_node.depth )
since: “meeting the oracle” since: “a year before the movie”cooperates on: “The Nebuchadnezzar”
Graph traversals
import neo4jclass Friends(neo4j.Traversal): # Traversals ! queries in Neo4j
types = [ neo4j.Outgoing.KNOWS ]order = neo4j.BREADTH_FIRSTstop = neo4j.STOP_AT_END_OF_GRAPHreturnable = neo4j.RETURN_ALL_BUT_START_NODE
23
name: “Thomas Anderson”age: 29
name: “Morpheus”rank: “Captain”occupation: “Total badass”
name: “Trinity”
name: “Cypher”last name: “Reagan”
name: “Agent Smith”version: “1.0b”language: “C++”
name: “The Architect”
KNOWS
KNOWS
KNOWSKNOWS
KNOWSCODED BY
LOVES
disclosure: “secret”
disclosure: “public”
Morpheus (@ depth=1)
Trinity (@ depth=1)
Cypher (@ depth=2)
for friend_node in Friends(mr_anderson):print "%s (@ depth=%s)" % ( friend_node["name"],
friend_node.depth )
since: “meeting the oracle” since: “a year before the movie”cooperates on: “The Nebuchadnezzar”
Graph traversals
import neo4jclass Friends(neo4j.Traversal): # Traversals ! queries in Neo4j
types = [ neo4j.Outgoing.KNOWS ]order = neo4j.BREADTH_FIRSTstop = neo4j.STOP_AT_END_OF_GRAPHreturnable = neo4j.RETURN_ALL_BUT_START_NODE
23
name: “Thomas Anderson”age: 29
name: “Morpheus”rank: “Captain”occupation: “Total badass”
name: “Trinity”
name: “Cypher”last name: “Reagan”
name: “Agent Smith”version: “1.0b”language: “C++”
name: “The Architect”
KNOWS
KNOWS
KNOWSKNOWS
KNOWSCODED BY
LOVES
disclosure: “secret”
disclosure: “public”
Morpheus (@ depth=1)
Trinity (@ depth=1)
Cypher (@ depth=2)
Agent Smith (@ depth=3)
for friend_node in Friends(mr_anderson):print "%s (@ depth=%s)" % ( friend_node["name"],
friend_node.depth )
since: “meeting the oracle” since: “a year before the movie”cooperates on: “The Nebuchadnezzar”
Graph traversals
import neo4jclass Friends(neo4j.Traversal): # Traversals ! queries in Neo4j
types = [ neo4j.Outgoing.KNOWS ]order = neo4j.BREADTH_FIRSTstop = neo4j.STOP_AT_END_OF_GRAPHreturnable = neo4j.RETURN_ALL_BUT_START_NODE
23
name: “Thomas Anderson”age: 29
name: “Morpheus”rank: “Captain”occupation: “Total badass”
name: “Trinity”
name: “Cypher”last name: “Reagan”
name: “Agent Smith”version: “1.0b”language: “C++”
name: “The Architect”
KNOWS
KNOWS
KNOWSKNOWS
KNOWSCODED BY
LOVES
disclosure: “secret”
disclosure: “public”
Morpheus (@ depth=1)
Trinity (@ depth=1)
Cypher (@ depth=2)
Agent Smith (@ depth=3)
for friend_node in Friends(mr_anderson):print "%s (@ depth=%s)" % ( friend_node["name"],
friend_node.depth )
Finding a place to start๏Traversals need a Node to start from
•QUESTION: How do I find the start Node?
•ANSWER: You use an Index
๏ Indexes in Neo4j are different from Indexes in Relational Databases
•RDBMSes use them for Joining
•Neo4j use them for simple lookup
24
IndexService index = getGraphDbIndexServiceSomehow();
Node mrAnderson = index.getSingleNode( "name", "Thomas Anderson" );
performTraversalFrom( mrAnderson );
Indexes in Neo4j๏The Graph *is* the main index
•Use relationship labels for navigation
•Build index structures *in the graph*
‣Search trees, tag clouds, geospatial indexes, et.c.
‣Linked/skip lists or other data structures in the graph
‣We have utility libraries for this
๏External indexes used *for lookup*
• Finding a (number of) points to start traversals from
•Major difference from RDBMS that use indexes for everything
25
A domain object implemented in Neo4jpublic interface Person {
String getName();void setName( String firstName, String lastName );
}
public final class PersonImpl implements Person {private final Node underlyingNode;public PersonImpl( Node underlyingNode ) {
this.underlyingNode = underlyingNode;}public String getName() {
return String.format("%s %s",underlyingNode.getProperty("first name"),underlyingNode.getProperty("last name") );
}public String setName(String firstName, String lastName) {
underlyingNode.setProperty("first name", firstName);underlyingNode.setProperty("last name", lastName);
}} 26
Neo4j as Software Transactional Memory๏ Implement objects as wrappers around Nodes and Relationships
•Neo4j is fast enough to allow you to read all state from the Node/Relationship
๏Mutating operations require transactions
•The changes are isolated from all other threads until committed
•Multiple mutations can be committed atomically
๏Nested transactions are flattened
•Makes it possible to have methods open their own transaction
๏Fits nicely with the OO paradigm
•More focus on data than on objects (comp. Object DBs) 27
Why not use an O/R mapper?๏Model evolution in ORMs is a hard problem
• virtually unsupported in most ORM systems
๏SQL is “compatible” across many RDBMSs
• data is still locked in
๏Each ORM maps object models differently
•Moving to another ORM == legacy schema support
‣except your legacy schema is a strange auto-generated one
๏Object/Graph Mapping is always done the same way
• allows you to keep your data through application changes
• or share data between multiple implementations 28
Path exists in social network๏Each person has on average 50 friends
30
Database # persons query timeRelational databaseNeo4j Graph DatabaseNeo4j Graph DatabaseRelational database
1 000 2 000 ms1 000 2 ms
1 000 000 2 ms1 000 000 way too long...
Tobias
Emil
JohanPeter
The performance impact in Neo4j depends only on the degree of each node. in an RDBMS it depends on the number of entries in the tables involved in the join(s).
Path exists in social network๏Each person has on average 50 friends
30
Database # persons query timeRelational databaseNeo4j Graph DatabaseNeo4j Graph DatabaseRelational database
1 000 2 000 ms1 000 2 ms
1 000 000 2 ms1 000 000 way too long...
Tobias
Emil
JohanPeter
The performance impact in Neo4j depends only on the degree of each node. in an RDBMS it depends on the number of entries in the tables involved in the join(s).
Path exists in social network๏Each person has on average 50 friends
30
Database # persons query timeRelational databaseNeo4j Graph DatabaseNeo4j Graph DatabaseRelational database
1 000 2 000 ms1 000 2 ms
1 000 000 2 ms1 000 000 way too long...
Tobias
Emil
JohanPeter
The performance impact in Neo4j depends only on the degree of each node. in an RDBMS it depends on the number of entries in the tables involved in the join(s).
Path exists in social network๏Each person has on average 50 friends
30
Database # persons query timeRelational databaseNeo4j Graph DatabaseNeo4j Graph DatabaseRelational database
1 000 2 000 ms1 000 2 ms
1 000 000 2 ms1 000 000 way too long...
Tobias
Emil
JohanPeter
The performance impact in Neo4j depends only on the degree of each node. in an RDBMS it depends on the number of entries in the tables involved in the join(s).
Path exists in social network๏Each person has on average 50 friends
30
Database # persons query timeRelational databaseNeo4j Graph DatabaseNeo4j Graph DatabaseRelational database
1 000 2 000 ms1 000 2 ms
1 000 000 2 ms1 000 000 way too long...
Tobias
Emil
JohanPeter
The performance impact in Neo4j depends only on the degree of each node. in an RDBMS it depends on the number of entries in the tables involved in the join(s).
๏20 million Nodes - represents places
๏62 million Edges - represents direct roads between places
•These edges have a length property, for the length of the road
๏Average optimal route, 100 separate roads, found in 100ms
๏Worst case route we could find:
•Optimal route is 5500 separate roads
•Total length ~770km
• Found in less than 3 seconds
๏Uses A* “best first” search
On-line real time routing with Neo4j
31
There’s a difference between least number of hops and least cost.
Routing with Neo4j - using Neo4j Graph-Algos# The cost evaluator - for choosing the best next nodeclass GeoCostEvaluator
include EstimateEvaluatordef getCost(node, goal)
straight_path_distance(node.getProperty("lat"), node.getProperty("lon"),goal.getProperty("lat"), goal.getProperty("lon") )
endend
# Instantiate the A* search functionpath_finder = AStar.new( Neo4j::instance,
RelationshipExpander.forTypes(DynamicRelationshipType.withName("road"),
Direction::BOTH ),DoubleEvaluator.new("length"), GeoCostEvaluator.new )
# Find the best path between New York City and San Franciscobest_path = path_finder.findSinglePath( NYC, SF )
32
Newest addition: Neo4j lets you REST๏Hello Neo4j REST server - Neo4j no longer needs to be embedded
๏Opens up Neo4j to your favorite platform (even if that isn’t Java)
• PHP, .NET, et.c. - libraries already exists!
• http://wiki.neo4j.org/content/Getting_Started_REST
๏Uses JSON for state transfer + browsable HTML for introspection
๏Atomic modification operations
๏Brand new declarative traversal framework
• Extensible using your favorite scripting language
‣javascript is included. Jython, JRuby, et.c. supported33
Other cool Graph Databases๏Sones GraphDB
•Graph Query Language - a SQL-like query language for graphs
๏Franz Inc. AllegroGraph
๏HypergraphDB
๏ InfoGrid
๏Twitter’s FlockDB
•Optimized for the Twitter use case - one level relationships
๏ Interestingly we all have different approaches34
One database to rule them all
35Image credits: The Lord of the Rings, New Line Cinema
Up until recently there was only one Database, the RDBMS. The days of a single database that rules all is over.
Use best suited storage for each kind of data
36Image credits: Unknown :’(
The era of using RDBMSes for all problems is over.Instead we should use the database most suited for the problem at hand.
Polyglot persistence
37
... we could even use multiple databases in conjunction, and let each database handle the things it does best.
{...}
{...}
{...}
Document
Polyglot persistence
38
SQL && NOSQL
All databases are welcome!SQL and NOSQL - it is Not Only SQL!
{...}
{...}
{...}
Document
Finding out more
39
๏http://neo4j.org/ - project website
‣http://api.neo4j.org/ and http://components.neo4j.org/
‣http://wiki.neo4j.org/ - HowTos, Tutorials, Examples, FAQ, et.c.
‣http://planet.neo4j.org/ - aggregation of blogs about Neo4j
๏http://neotechnology.com/ - commercial licensing
๏http://twitter.com/neo4j/team - follow the Neo4j team
๏http://nosql.mypopescu.com/ - good source for news on NOSQLmonitors Neo4j and other NOSQL solutions
๏http://highscalability.com/ - has published a few articles about Neo4j
Buzzword summary
40
AGPLv3 ACID transactions
Embedded
NOSQL
Beer
A* routing
Open Source
Free Software
http://neo4j.org/
Software Transactional Memory
whiteboard friendly
Object mapping
Traversal Query language
SPARQL
Scaling to complexity
Shortest path
Semi structured
Schema free
Polyglot persistence
Right tool for the right job
RESTful
GremlinIn-Graph indexes