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NoSQLUsing the right tool for the right job
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No SQL
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No SQL
Not Only/ I /I
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No SQL
Not Only/ I /I/
/
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No SQL
Not Only/ I /I/
/Relational
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Need to store some data ?
Oracle
SQL Server
Sybase
DB2
MySQL
PostgreSQL
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RDBMS are great for relational
storage !
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RDBMS may not be fully trivial…
…what a pity if you just wanted
a put / get store
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How to achievescalability and
high availabilitywith a RDMS ?
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Memcached can help to reduce the
pressure on RDBMS
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But this wasn’t enough for some
people…
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The birth of Dynamo at
Amazon.com…
Fill cart Checkout Payment Process order Prepare Send
Write must ALWAYS be available Only key-value is required
Temporal unavailability is acceptableRich storage is preferred for reporting
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So they started to create their own
database that would match their
needs… Table de hachage
persistante
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So they started to create their own
database that would match their
needs…
Table de hachage
persistante
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Consistent hashing spreads keys
uniformally across the partitions
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Sharding brings scalability,
replication brings high availability
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But failures still have to be handled
efficiently…
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In case of failure of a node, the 2 other nodes serve its load
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In this configuration,
clients know only few nodes which
act as proxy to other nodes…
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Gossip protocol to let everybody know node B has failed…
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Eventual consistency…
N = Number of replicas
R = Number of read responses to wait for
W = Number of write aknowledges to wait for
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The ratio between N, R and W makes
everything…
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The ratio between N, R and W makes
everything…
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The ratio between N, R and W makes
everything…
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Key-value storesare simple…
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Several competitors…
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Riak…
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Riak…
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Document oriented databases are an evolution of key-
value stores
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MongoDB is the leader so far…
… 10gen said they are the « MySQL of
NoSQL »
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MongoDB is the leader so far…
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MongoDB is the leader so far…
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Graph databases are great to store…
graphs !
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Neo Technology is the leader so far
with Neo4j…
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Neo4j…
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Column-oriented databases have a
very particular data model…
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CassandraVs
HBase !
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Cassandra adds SuperColumns to
this model…
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Cassandra was developped at
Facebook, to store the user messages
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Now also used by Digg, Twitter, Rackspace,…
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What a model…
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An example…
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Cassandra Demo
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