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...
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
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!
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
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} ))
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
