Hinnerk Haardt

Warum NoSQL?
Hinnerk Haardt <[email protected]>
Not only SQL
SQL
Structured 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
RAM
CPU
Storage
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Storage
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Storage
teurer →
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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mehr Daten →
horizontale
Skalierung
vertikale
Skalierung
mehr Durchsatz & höhere Verfügbarkeit →
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Verfügbarkeit
Sicherheit (ACID)
Verfügbarkeit
unbegrenztes Wachstum
CAP-Theorem
Consistency
Availability
Partition Tolerance
»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