warum nosql?

Warum NoSQL?Hinnerk Haardt <hinnerk@randnotizen.de>

Not only SQL

SQLStructured Query

Language

Programmiersprache für relationale

Datenbanken

Warum?

Das Internet ist schuld!

1980er: data bank

ACID

• Atomicity — ganz oder gar nicht

• Consistency — gewährleistet Integrität

• Isolation — Kapselung gleichzeitiger T.

• Durability — Persistenz aller Änderungen

»große« Datenbanken

Skalieren vertikal

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Storage

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teur

er →

größer →

21. Jh.

Beispiel Facebook

• 30.000 Server

• 25 Terabyte Logdaten täglich

• 300.000.000 Nutzer

• 230 Ingenieure

Das Internet ist schuld.

Horizontal

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meh

r D

aten

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mehr Durchsatz & höhere Verfügbarkeit →

vertikaleSkalierung

horizontaleSkalierung

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Verfügbarkeit

Sicherheit (ACID)Verfügbarkeitunbegrenztes Wachstum

CAP-Theorem

Consistency

Partition Tolerance

Availability

»in larger distributed-scale systems, network partitions are a given; therefore, consistency and availability cannot be achieved at the same time«

Werner Vogels, Amazon.com

2009: NoSQL

Definition…

»Gruppe nicht konventioneller Datenbanken«

Willkommen im Zoo!

• CouchDB

• MongoDB

• Redis

• Memcachedb

• Tokyo Cabinet

• Google BigTable

• Amazon Dynamo

• Apache Cassandra

• Project Voldemort

• Mnesia (Erlang)

• Hbase (Apache Hadoop)

• Hypertable

• Twitter Gizzard

kein ACID

eingeschränkte Transaktionen

kein »JOIN«

kein SQL

einfach anzusprechen

schemafrei

skaliert horizontal

Replikation

eventual consistency

probabilistic worldview

Amazon's Dynamo

• »applications have received successful responses […] for 99.9995% of its requests«

• »no data loss event has occurred to date« [2007, nach 2 Jahren Betrieb]

Veranstaltung»ACID vs. BASE«

• mehr zu NoSQL, ACID, BASE und dem CAP-Theorem

• Objekt-Stammtisch Kiel

• 27.04.2010 19:00 Uhr

• Eckernförder Straße 20, Kiel (Toppoint)

Referenzen

• Bigtable: A Distributed Storage System for Structured Data

• Eventually Consistent - Revisited

• Keynote address to the PODC conference in 2000 by Eric Brewer

• Brewer's conjecture and the feasibility of consistent, available, partition-tolerant web services