ArangoDB - Using JavaScript in the database

ArangoDB

/* Using Javascript
in the database */

Jan Steemann, triAGENS, Cologne

ArangoDB
basics

www.arangodb.org © j.steemann@triagens.de

ArangoDB.explain()

{
"type": "NoSQL database",
"openSource": true,
"version": 1.0,
"builtWith": [ "C", "C++", "js" ],
"Javascript": [ "client side",
"server side" ],
"uses": [ "V8" ]
}


Documents
and collections
ArangoDB is a database that works with
documents

Documents are sets of name / value pairs
(think of JSON objects), e.g.

{ "name": "Jan", "age": 37 }

Documents are organised in collections (like
tables in relational databases)


Data types: JSON!

ArangoDB operates on JSON documents

JSON data can be saved as-is:

db.users.save({
"name": "Jan",
"uses": [ "vi", "js", "C++" ]
});


Schema-free
Documents can be heterogenous –
even in the same collection, e.g.

{ "name": "Jan", "age": 37 },
{ "name": "Tim", "likes": [ "js" ] },
{ "name": {
"first": "Patrick",
"last": "Star"
}
}

No need to care about schemas

API & protocols
ArangoDB server functionality is exposed via an
HTTP REST API

ArangoDB answers HTTP queries,
so it can be used from the browser

Simple to use from Javascript clients

(3rd party) drivers available for node.js, Ruby,
PHP, ...

Javascript-enabled client shell provided


Querying


Querying is simple

Query a document by its unique id / key:
db._document("users/9558905");

Query by providing an example:
db.users.byExample({
"name": "Jan",
"age": 37
});


Indexes
ArangoDB allows querying on any document
attributes or sub-attributes

Secondary indexes can be created for higher
query performance:
• Hash indexes (equality queries)
• Skiplists (range queries)
• 2d geo indexes (location queries)


Geo index examples

// get b a r n ea r es t t o coor d in a t e
db.bars.near(48.51, 2.21).limit(1);

// get a ll s h op s w it h in r a d iu s
// a r ou n d coor d in a t e
db.shops.within(48.51, 2.21, rad);


References
ArangoDB can store references between
documents

References are documents with two endpoints
(the documents they connect)

Reference documents can carry own attributes


References example
Users documents: Relations documents:
(references)
{
"name": "Jan",
"age": 37 {
} "_from": "users/jan",
"_to": "users/tim",
{ "type": "knows",
"name": "Tim", }
"city": "Paris"
}

// q u er y ou t b ou n d r ela t ion s f r om "J a n "
db.relations.outEdges(jan); // => tim

Graph queries

References make it possible to process graphs
with ArangoDB

Some special functions are provided to
determine paths in a graph etc.

Can write own Javascript functions for special
traversals


Query language

ArangoDB can also answer complex
SQL-like queries

Such queries are expressed in ArangoDB's
textual query language

This language allows joins, sub-queries,
aggregation etc.


Example query
FOR u IN users It er a t or
FILTER u.addr.country == "US" &&
(u.isConfirmed == true ||
u.age >= 18) F ilt er
LET userLogins = (
FOR l IN logins
FILTER l.userId == u.id
RETURN l
) S u b q u er y
RETURN {
"user": u,
"logins": LENGTH(userLogins)
} R es u lt

Server side „actions“


Application server

ArangoDB can answer web requests directly

This also makes it an application server

Users can extend its functionality with server
side Javascript „actions“

Actions are user-defined functions that contain
custom business logic


Actions

Actions are bound to URLs and executed when
URLs are called, e.g.

/users?name=... => function(...)
/users/.../friends => function(...)


Actions example
function (req, res) {
// get r eq u es t ed u s er f r om d b ,
// n a m e is r ea d f r om U R L p a r a m et er
var u = db.users.byExample({
"username": req.urlParameters.name
});

// r em ov e p a s s w or d h a s h
delete u.hashedPassword;

// b ef or e r et u r n in g t o ca ller
actions.resultOk(req, res, 200, u);
}

Actions – Use cases
Filter out sensitive data before responding

Validate input

Check privileges

Check and enforce constraints

Aggregate data from multiple queries into a single
response

Carry out data-intensive operations


Summary


ArangoDB - summary
Flexible in terms of data modelling and querying

API is based on web standards:
HTTP, REST, JSON

Easy to use from Javascript clients

Can be used as application server

Functionality can be extended with server side
Javascript „actions“


Thanks!
Any questions?
Спасибо Grazie

Teşekkürler ¡Gracias!

Merci! Хвала

Dank je wel Ευχαριστώ

ありがとう 고마워

Tack så mycket Danke


Give it a try!
ArangoDB source repository:
https://www.github.com/triAGENS/ArangoDB
(use master branch)

Website: http://www.arangodb.org/

Builds available for Homebrew and
several Linux distributions

Twitter: #arangodb, @arangodb

Google group: ArangoDB

Roadmap

MVCC / ACID transactions

Triggers

Synchronous and asynchronous replication


Thank you!
Stay in Touch:
• Fork me on github
• Google Group: ArangoDB
• Twitter: @steemann & @arangodb
• www.arangodb.org


ArangoDB - Using JavaScript in the database

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