NoSQL and Triple Stores
Andy Seaborne
NoSQL
From http://nosql-database.org/
Graph Databases
Key-Value stores
Column Stores
Document Stores
Triples Stores
NoSQL
Non-relational
Distributed
Open-source
horizontally scalable
Schema-free
easy replication support
simple API
eventually consistent / BASE (not ACID)
a huge data amount
From http://nosql-database.org/
Triple Stores
Data Model: RDFSubject-predicate-object
Don't store triplesthey store named sets of triples
Schema-lessDump and run data management
SPARQLQuery Language
Protocol using HTTP
RDF
Ant in Action
title
creatorAuthor
Steve Loughranname
193239480XISBN10
creatorAuthor
Erik Hatchernamehttp://webbooks/b4598
RDF
Ant in Action
title
creatorAuthor
Steve Loughranname
193239480XISBN10
creatorAuthor
Erik HatchernameshopStock item
item
$49.99pricerefhttp://webbooks/b4598
RDF
Ant in Action
title
creatorAuthor
Steve Loughranname
193239480XISBN10
creatorAuthor
Erik HatchernameshopStock item
gooditem
$49.99pricerefcreatorrating
Andy Seabornehttp://review.org/review57http://webbooks/b4598
Turtle
@prefix : .@prefix rdf: .@prefix foaf: .
:Andy a foaf:Person ; foaf:name "Andy Seaborne" ; foaf:mbox ;
foaf:knows :Paolo ; foaf:knows :Steve .
:Paolo a foaf:Person ; foaf:name "Paolo Castagna" ; foaf:mbox
.
:Steve foaf:name "Steve Loughran" ; foaf:mbox_sha1
"0678d36518d039a64ee4baba0a568afe535ce5f3" .
RDF
RDF is a graph
Your computer thinks of this is as a logical table (but probably
stores it differently)
SubjectPredicateObject
A SPARQL Query Looks Like
@prefix person: .@prefix foaf: .
person:A foaf:name "Alice" .person:A foaf:mbox .person:B
foaf:name "Bob" . PREFIX person: PREFIX foaf:
SELECT ?name
WHERE
{ ?person foaf:mbox . ?person foaf:name ?name . } -----------| name
|===========| "Alice" |-----------
@prefix dc: .@prefix stock: .
stock:book1 dc:title "SPARQL Query Language Tutorial"
.stock:book2 dc:title "SPARQL Query Language (2nd ed)" .stock:book3
dc:title "Moving from SQL to SPARQL" .stock:book4 dc:title
"Applying XQuery" .
PREFIX dc: PREFIX stock:
SELECT ?book ?title{ ?book dc:title ?title . FILTER
(regex(?title,
"SPARQL"))}--------------------------------------------------| book
| title |==================================================|
stock:book3 | "Moving from SQL to SPARQL" || stock:book2 | "SPARQL
Query Language (2nd ed)" || stock:book1 | "SPARQL Query Language
Tutorial" |--------------------------------------------------A
SPARQL Query Looks Like
SPARQL: All people who know 3 others
PREFIX rdf: PREFIX foaf:
SELECT ?name{ { SELECT ?x (count(*) AS ?count) { ?x foaf:knows
?y . } GROUP BY ?x HAVING (?count = 3) } ?x foaf:name ?name .}
SPARQL Protocol
GET /foo/sparql?query=SELECT (Count(*) AS ?c) { ?s ?p ?o
}Accept: application/sparq-results+json
GET
/foo/sparql?query=SELECT%20%28Count%28%2A%29%20AS%20%3Fc%29%20{%20%3Fs%20%3Fp%20%3Fo%20}
{ "head": { "vars": [ "c" ] } , "results": { "bindings": [ {
"c": { "datatype": "http://www.w3.org/2001/XMLSchema#integer" ,
"type": "typed-literal" , "value": "10" } } ] }}
SPARQL Graph Store Protocol
Simple way to manage a store
GET, PUT, POST, DELETE
NamingSame server
http://server/store/graph1
Different server
http://server/store?graph=http://example/g1
http://server/store?graph=http%3A//example/g1
RESTful operation
PUT /store?graph=http%3A//example/g1 HTTP/1.1Host:
server.comContent-type: application/rdf+xml
...
Triples Store as NoSQL
Mostly open source
Some distributed
API Not proprietary
Looks like SQL
Eventual consistency
Huge amount of data?Garlik: 20 Billion triples (cluster, ~20
machines)
AllegroGraph: 1 Trillion (single, very large machine)
08/09/11
