Databasesthe Choice Is Yours

Philipp Krenn @xeraa

Infrastructure | Developer Advocate

"relational model and normal form"

↓

"data independence"

Relational AlgebraBook "Seven Databases in Seven Weeks"

DeclarativeImplementation detail of the RDBMS

(Query Optimizer)

User InteractionAggregated reports

Concurrency, integrity, consistency, type-safety

From a

Wide Variety of Databasesto

A Dark Age

http://blog.8thlight.com/uncle-bob/2012/05/15/NODB.html

Slow &inflexible

Schema Flexibilityhttp://pragprog.com/magazines/2012-05/beyond-the-bit-bucket

NoSQLNot Only SQL

Big DataVery broad, including NoSQL

Offline data / data warehouse,Hadoop & Spark

http://db-engines.com/en/ranking

CouchDB, Couchbase, Elasticsearch,...

Ted Neward: ORM is "The Vietnam of Computer Science"

http://blogs.tedneward.com/post/the-vietnam-of-computer-science/

@OneToMany(mappedBy = "destCustomerId")@ManyToMany@Fetch(FetchMode.SUBSELECT)@JoinTable(name = "customer_dealer_map", joinColumns = { @JoinColumn(name = "customer_id", referencedColumnName = "id")}, inverseJoinColumns = { @JoinColumn(name = "dealer_id", referencedColumnName = "id")})private Collection<Client> dealers;

public abstract class EmployeeEntity { protected String name;}public class ManagerEntity extends EmployeeEntity { protected Boolean approveFunds;}public class WorkerEntity extends EmployeeEntity { protected Integer yearsExperience;}

RDBMS1. Union table with (many) NULL

values

RDBMS2. Concrete instances without common

queries

RDBMS3. Base table JOINed with concrete

instances

@Entity(value = "employee")public abstract class EmployeeEntity { @Id protected ObjectId id; protected String name;}public class ManagerEntity extends EmployeeEntity { protected Boolean approveFunds;}public class WorkerEntity extends EmployeeEntity { protected Integer yearsExperience;}

{ "_id": ObjectId("5461c8bf9e2acf32ed50c079"), "className": "net.xeraa.morphia_demo.entities.ManagerEntity", "name": "Peter", "approveFunds": true}{ "_id": ObjectId("524d9fe7e4b0f8bd3031f84e"), "className": "net.xeraa.morphia_demo.entities.WorkerEntity", "name": "Philipp", "yearsExperience": 10}

Key-Value Storeand more

REmote DIctionary Server

Statistics (Login)Bitset

HyperLogLog

BitsetFirst user bit 1, second user bit 2,...

A million users ~123KB

HyperLogLogUnique elements in 12KB regardless of

their numberError rate ~0,81%

http://redis.io/commands/pfcount

ComparisonHyperLogLog: constant sizeBitset: exact & aggregates

Scalable & highly available

Consistent Hashing

Eventually consistent was too hard, so we went with

immediately inaccurate.— https://twitter.com/mysqlborat/status/621785755107524608

SQL Databasesnot only RDBMS

Cassandra Query Language (CQL)Google Query Language (GQL)

Couchbase N1QLRethinkDB Query Language (ReQL)

RDBMS features & maturity+

NoSQL influence

Full-Text Search

Document ScoreTerm Frequency (TF) / Inverse

Document Frequency (IDF)Field-length norm

https://www.elastic.co/guide/en/elasticsearch/guide/current/scoring-theory.html

Conclusion

But is it fast?

Thanks!Questions? Swag

@xeraa

CreditsSchnitzel https://flic.kr/p/9m27wm

Architecture https://flic.kr/p/6dwCAeConchita https://flic.kr/p/nBqSHT

Twelve: https://flic.kr/p/3iRDd9Consistent hashing https://

highlyscalable.wordpress.com/2012/09/18/

CreditsFull-text search https://developer.apple.com/library/mac/documentation/UserExperience/

Conceptual/SearchKitConcepts/searchKit_basics/searchKit_basics.htmlNo, SQL https://twitter.com/edd/status/

400190499585544192