In many modern applications the database side is realized using polyglot persistence – store each data format (graphs, documents, etc.) in an appropriate separate database. This approach yields several benefits, databases are optimized for their specific duty, however there are also drawbacks: * keep all databases in sync * queries might require data from several databases * experts needed for all used systems A multi-model database is not restricted to one data format, but can cope with several of them. In this talk i will present how a multi-model database can be used in a polyglot persistence setup and how it will reduce the effort drastically.

1. www.arangodb.com
Polyglot Persistence
&
Multi-Model Databases
Michael Hackstein
@mchacki
NoSQL Matters Paris

2. Michael Hackstein
‣ ArangoDB Core Team
‣ Web Frontend
‣ Graph visualisation
‣ Graph features
‣ Host of cologne.js
‣ Master’s Degree
(spec. Databases and
Information Systems)
2

3. The Single Model era is over
3
Relational World

4. The Multi Model era begins
4
NoSQL World
Documents - JSON
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
K => V
Graphs
Key Value
{
“type“: "pants",
“waist": 32,
“length”: 34,
“color": "blue",
“material”: “cotton"
}
{
“type“: "television",
“diagonal screen size": 46,
“hdmi inputs": 3,
“wall mountable": true,
“built-in digital tuner": true,
“dynamic contrast ratio”: “50,000:1”,
Resolution”: “1920x1080”
}
{
“type": "sweater",
“color": "blue",
“size": “M”,
“material”: “wool”,
“form”: “turtleneck"
}
{
“type": "sweater",
“color": "blue",
“size": “M”,
“material”: “wool”,
“form”: “turtleneck"
}
‣ Map value data to unique string keys (identifiers)
‣ Treat data as opaque (data has no schema)
‣ Can implement scaling and partitioning easily
‣ Focussed on m-to-n relations between entities
‣ Stores property graphs: entities and edges can have
attributes
‣ Easily query paths of variable length
‣ Normally based on key-value stores (each document still
has a unique key)
‣ Allow to save documents with logical similarity in
“collections”
‣ Treat data records as attribute-structured documents
(data is no more opaque)
‣ Often allow querying and indexing document attributes

5. An e-commerce system in Relational World
5
Sales-History
Shopping-Cart
Recommendations Customer
Product-Catalog

6. Polyglot Persistence
6
Source: Martin Fowler, http://martinfowler.com/articles/nosql-intro.pdf
Reporting
RDBMS
Product Catalog
MongoDB
Shopping Cart
Riak
User activity log
Cassandra
Analytics
Cassandra
Recommendations
Neo4J
Financial Data
RDBMS
User Sessions
Redis
Shopping Cart
KeyValue
Reporting
RDBMS
Product Catalog
Document
User activity log
Column
Analytics
Column
Recommendations
Graph
Financial Data
RDBMS
User Sessions
KeyValue

7. Single Model Databases
7
Recommendations
Product-CatalogShopping-Cart
Sales-History Customer
{
“userID": 239178239,
“productID”: 128623883,
“number": 5,
“price”: 12.20,
}
{
“userID": 239178239,
“productID”: 128623883,
“number": 5,
“price”: 12.20,
}
{
“Name": "Smith",
“lastLogin”: “2012-11-01",
“Visits": 121,
“shipping address”: “abc”,
“shipping address”: “def”
}
{
“Name": "Meyer",
“lastLogin”: “2012-11-21",
“Visits": 20,
“shipping address”: “xyz”,
}
423453453
4328, “shirt”, “L”, 1, 12.99
6378, “sweater”, “M”, 2, 37.95
3245, “sweater”, “blue”, 1, 99.95
3245, “pants”, “32/34”, “black”, 1, 99.95
=>
874365563
5463, “shirt”, “S”, 1, 9.99
6378, “sweater”, “M”, 2, 37.95
3245, “pants”, “32/34”, “black”, 1, 99.95
=>
{
“type“: "pants",
“waist": 32,
“length”: 34,
“color": "blue",
“material”: “cotton"
}
{
“type“: "television",
“diagonal screen size": 46,
“hdmi inputs": 3,
“wall mountable": true,
“built-in digital tuner": true,
“dynamic contrast ratio”: “50,000:1”,
Resolution”: “1920x1080”
}
{
“type": "sweater",
“color": "blue",
“size": “M”,
“material”: “wool”,
“form”: “turtleneck"
}
{
“type": "sweater",
“color": "blue",
“size": “M”,
“material”: “wool”,
“form”: “turtleneck"
}
DocumentStore GraphStore DocumentStore
DocumentStoreKeyValueStore

8. Benefits
‣ Natural mapping of data
into DB
‣ DB optimized for the data
format
‣ Queries are tailored for
your data format
‣ Focus on writing business
logic
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‣ Data has to be stored
redundantly and has to be
kept in sync
‣ Several technologies
involved
‣ Administration effort is
huge
Overhead&

9. Solution: Multi Model Database
‣ Can natively store several kinds of data models:
‣ Key-value pairs
‣ Documents
‣ Graphs
‣ Delivers query mechanisms for all data models
9

10. Polyglot Persistence Revisited
10
Source: Martin Fowler, http://martinfowler.com/articles/nosql-intro.pdf
Shopping Cart
KeyValue
Reporting
RDBMS
Product Catalog
Document
User activity log
Column
Analytics
Column
Recommendations
Graph
Financial Data
RDBMS
User Sessions
KeyValue
Reporting
RDBMS
Product Catalog
ArangoDB
Shopping Cart
ArangoDB
User activity log
Cassandra
Analytics
Cassandra
Recommendations
ArangoDB
Financial Data
ArangoDB
User Sessions
ArangoDB

11. Use Case: Multi-Model-Databases
11
Recommendations
Product-CatalogShopping-Cart
Sales-History Customer
{
“userID": 239178239,
“productID”: 128623883,
“number": 5,
“price”: 12.20,
}
{
“userID": 239178239,
“productID”: 128623883,
“number": 5,
“price”: 12.20,
}
{
“Name": "Smith",
“lastLogin”: “2012-11-01",
“Visits": 121,
“shipping address”: “abc”,
“shipping address”: “def”
}
{
“Name": "Meyer",
“lastLogin”: “2012-11-21",
“Visits": 20,
“shipping address”: “xyz”,
}
423453453
4328, “shirt”, “L”, 1, 12.99
6378, “sweater”, “M”, 2, 37.95
3245, “sweater”, “blue”, 1, 99.95
3245, “pants”, “32/34”, “black”, 1, 99.95
=>
874365563
5463, “shirt”, “S”, 1, 9.99
6378, “sweater”, “M”, 2, 37.95
3245, “pants”, “32/34”, “black”, 1, 99.95
=>
{
“type“: "pants",
“waist": 32,
“length”: 34,
“color": "blue",
“material”: “cotton"
}
{
“type“: "television",
“diagonal screen size": 46,
“hdmi inputs": 3,
“wall mountable": true,
“built-in digital tuner": true,
“dynamic contrast ratio”: “50,000:1”,
Resolution”: “1920x1080”
}
{
“type": "sweater",
“color": "blue",
“size": “M”,
“material”: “wool”,
“form”: “turtleneck"
}
{
“type": "sweater",
“color": "blue",
“size": “M”,
“material”: “wool”,
“form”: “turtleneck"
}
DocumentStore GraphStore DocumentStore
DocumentStoreKeyValueStore

12. My four favorite features of
‣ AQL offering joins & traversals
‣ ACID including Multi Collection Transactions
‣ MULTI-MODEL stores graphs and documents
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‣ FOXX extend the API and adapt it to your needs

13. AQL
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FOR p IN products
RETURN p
FILTER p.color == "yellow"
FOR d IN GRAPH_DISTANCE_TO("ecom", p._id,
"customer/alice", {direction: "inbound"})
LET r = {distance: x.distance, product: p}
FILTER r.distance > 1
SORT r.distance
LIMIT 10
RETURN r

14. ACID - Transactions
‣ Invoke a transaction:
db._executeTransaction({
collections: {
write: ["users", "products"],
read: "recommendations"
},
action: function() {
// all operations go here
}
});
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throw "failure"; // Triggers rollback

15. ‣ Native mapping of data into
DB
‣ DB optimized
‣ Queries are tailored for
your data format
‣ Focus on writing business
logic
15
‣ Data has to be stored
redundantly and has to be
kept in sync
‣ Several technologies
‣ Administration effort is
‣ One technology involved
Benefits Overhead&

16. Foxx
‣ Add your own customized and versioned REST-API on top of
ArangoDB in JavaScript
‣ Include as a microservice in Rails, Node.js etc.
‣ Ship an administration fronted with it
‣ Built-in authentication using OAuth2.0 or HTTP-Basic Auth
‣ Operations are encapsulated in the database
‣ low network traffic, direct data access
‣ increases data privacy
➡ Multi-device setups
➡ Microservice Architectures
/
(~(
) ) /_/
( _-----_(@ @)
( /
/|/--| V
" " " "
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17. Foxx Example
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FOR p IN products
FILTER p.color == @color
FOR d IN GRAPH_DISTANCE_TO("ecom", p._id,
"customer/alice", {direction: "inbound"})
LET r = {distance: x.distance, product: p}
FILTER r.distance > 1
SORT r.distance
LIMIT 10
RETURN r',
controller.get("/recommend/:color", function(req, res) {
res.json(db._query('FOR p IN products
});
{color: req.params("color")}).toArray());

18. ‣ open source and free (Apache 2 license)
‣ sharding & replication
‣ JavaScript throughout (V8 built into server)
‣ drivers for a wide range of languages
‣ web frontend
‣ good & complete documentation
‣ professional as well as community support
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An overview of other features

19. Join our growing community
19
.. working on the geo index, the full text search and
many APIs: Ruby, Python, PHP, Java, D, Javascript, ...

20. Thank you
‣ Further questions?
‣ Follow me on twitter/github: @mchacki
‣ Write me a mail: mchacki@arangodb.com
‣ Join or google group: https://groups.google.com/forum/#!forum/arangodb
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