This document summarizes the key new features in Neo4j 2.0 including: 1) The introduction of node labels which allow nodes to have multiple labels to identify and categorize nodes and improve query performance. 2) Schema indexing which allows indexes to be created for labels based on a property for simple lookups. 3) The MERGE operation which combines MATCH and CREATE to either match existing graph data or create new data if no match is found. 4) Transactions now being mandatory for all database interactions to improve consistency and isolation. 5) Various Cypher query language changes and improvements focused on making queries easier to write and read.

1. Webinar
Aug 8 2013
What‘s new in Neo4j 2.0
Michael Hunger, Neo Technology
@mesirii | @neo4j

2. BIG NEWS
Neo4j 2.0.0-M04 released today!

3. Neo4j 2.0

4. Why 2.0?

5. (0.x) --> (1.x) --> (2.x)
• 0.x was about embedded java
• 1.x introduced indexes, the server and REST
• 2.x ease of use, big data, cloud
which means a focus on...

6. This guy

7. Focus on Cypher
• Cypher, a carefully crafted language for working with graphs
• Declarative, friendly, easy to read and write
• One language, used everywhere
• REST for management, Java for extensions

8. What is new in 2.0?

9. Introducing: Node Labels

10. WORKS_WITH
Person
Employee
Developer
Husband
NoSQL
GraphDB
Database
Awesome!
No Schema is good
Some Structure is helpful

11. • Simply: a label identifies a set of nodes
• Nodes can have multiple labels
• Find nodes by label
• Constrain properties and values
(lightweight, optional schema)
• A simple idea, with powerful applications
Introducing Node Labels
NoSQL
GraphDB
Database
Awesome!

12. How to use labels?

13. Labels - how to use?
• To identify nodes
• To categorize, tag
• To represent types
• To avoid confusion
• For special nodes (domain specific reference nodes)

14. Labels - rules of thumb
• Use a label to make queries easier to read & write
• And to improve performance through indexing
• Start with anything you might've put in a legacy index
• Use lightly, as few labels as needed

15. Find friends who like cheese
MATCH (p:Person)-[:FRIENDS]->(friend:Person),
(friend) -[:LIKE]-> (thing:Thing)
WHERE p.name = "Max De Marzi"
AND thing:Food AND thing.name = "Cheese"
RETURN thing, labels(thing);

16. Schema Indexing
• Indexes for labels, based on a property
• Simple lookups for now
• Unique indexing coming soon
• Full-text, other special indexes in planning
CREATE INDEX ON :Person(name)
MATCH (p:Person)
WHERE p.name = „Max“
RETURN p

17. MERGE operation
• a combination of MATCH + CREATE
• replaces CREATE UNIQUE (currently still limited)
• attempts to MATCH, with specified properties and labels
• if match fails, new graph data is created
• optional sub-clauses for handling ON CREATE, and ON MATCH
MERGE (p:Person { name:'Charlie Sheen', age:10 })
ON CREATE p SET p.created = timestamp()
RETURN p

18. Hands-On Cypher
• Migrate Cineasts dataset to use Labels
• Show MATCH on Labels and Properties (+ profile)
• Add an Index on :Person(name) :Movie(title)
• Show MATCH on Labels and Properties (+ profile)
• Show MERGE with a user
https://gist.github.com/jexp/6193139#file-setup-start-sh
https://gist.github.com/jexp/6193139#file-upgrade-movie-database-to-2-0-cql

19. Demo

20. Anything else?
• Breaking changes to some APIs (read CHANGES.txt)
• Migration of "legacy" indexes (stop STARTing)
• Mandatory transactions for all DB interactions
• Improving installers (in progress)
• Changing everything to be "all Cypher, all the time"

21. Cypher Changes: Properties
• no schema -> what happens when properties don‘t exist
• has(n.prop) AND n.prop=“Foobar“
• there was syntactic sugar n.prop! and n.prop?
• now n.prop returns NULL covers n.prop! =“Foobar“
• explicit expression for n.prop? = „Foobar“
WHERE n.name = „Chris“
AND (not(m.name) OR m.name=“Andres“)

22. Cypher Changes: REMOVE
• consistent remove operations of labels and properties
• you REMOVE attributes (properties, labels)
• and DELETE elements (nodes, relationships)
REMOVE n.name
REMOVE n:People
DELETE node
DELETE relationship

23. Cypher Changes: Separators
• grammar has to be unambiguous
• extract(n in nodes:Foo)???
• confuse colon from label and collection function separator
• exchanged colon for pipe
EXTRACT (n in nodes | n.name)
FILTER (n in nodes | n.name =~ „And.*“)
FOREACH (v in names | CREATE ( {name: v} ))

24. Demo

25. Mandatory Transactions
• we had optional transactions for reads
• Issues:
• In which context do I read?
• Do I read what I read?
• Which changes do I see?
• NOW: Mandatory Transactions for reads and writes!
• only affects embedded API
• Cypher and REST-API take care of their transactions

26. • begin, commit, or rollback a transaction
• transaction as RESTful resource
• issue multiple statements per request
• multiple requests per transaction
• compact response format
• some driver already support it (neography, jdbc)
Transactional Cypher

27. Hands-On 2.0
• Show Transactional HTTP-Endpoint
• POST initial statements, look at result, check currently running tx in
server-info
• POST another create statement to the tx
• POST a new read statement to a new tx that shows isolation
• DELETE second transaction
• POST to COMMIT resource
https://gist.github.com/jexp/6193139#file-demo-transactional-endpoint-js

28. What is new in 2.0?
• It's all about Cypher, starting with
• Labels, the first significant change in over 12 years
• Mix in schema indexing
• Then transactional REST, new clauses, functions
• A fresh Web UI that is Cypher-focused

29. Thanks :)
MATCH (you)-[:HAVE]->(q:Question)
RETURN q.text
@neo4j or @mesirii to keep in touch