Cassandra - Say Goodbye to the Relational Database (5-6-2010)

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Cassandra
Say Goodbye to the Relation Database
Twin Cities PHP User Group
May 6, 2010
Chris Barber
CB1, INC.
http://www.cb1inc.com/

About Me

● Chris Barber
● Open source hacker
● Software consultant
● JavaScript, C++, PHP
● http://www.cb1inc.com/
● http://twitter.com/cb1inc
● http://twitter.com/cb1kenobi
● http://slideshare.net/cb1kenobi

Minnesota PHP User Group | 5.6.2010 | Chris Barber | CB1, INC. | http://www.cb1inc.com/

What is Cassandra?


A highly scalable, eventually
consistent, distributed,
structured key-value store.


About Cassandra
● Started by Facebook
● Open Source
● Apache Project
● Apache License 2.0
● Written in Java
● Mutli-platform
● Current Version 0.6.1
● http://cassandra.apache.org/


Who's using Cassandra?


Cassandra Internals


Cassandra Overview
● Like a big hash table of hash tables
● Column Database (schemaless)
● Highly scalable
● Add nodes in minutes
● Fault tolerant
● Distributed
● Tunable


Dynamo + BigTable = Cassandra
● Amazon Dynamo
● Cluster management
● Replication
● Fault tolerance
● Google BigTable
● Sparse
● Columnar data model
● Storage architecture


Pros & Cons
● Pros ● Cons
● Easy to scale ● No joins
● No single point of failure ● Index & sort keys only
● High write-through ● Not good for large blobs
● Handles lots of data ● Rows must fit in
● Durable memory
● No more SQL injection
● Built on Thrift


CAP Theorem
● CAP Theorem
● Consistency
● Availability
● Partitioning
● You can only have 2
● Cassandra is Available and Partitioning
● Eventually consistent
– Can be defined on a per request basis


Consistency
● Specified for each operation
● Zero
● One
● Quorum (N-1)
● All
● Any


Replication Ring
● Ring of servers
● Talk to each other using "gossip"
● Data distributed between nodes
● Uses "tokens" to partition data
● Must be unique per node


Partitioning
● RandomPartitioner
● Inefficient range queries
● Doesn't sort properly
● OrderPreservingPartitioner
● Can cause unevenly distributed data
● Stores data sorted


Replica Placement Strategy
● Rack-unware
● Default
● Rack-aware
● Place one replica in a different datacenter, and the
others on different racks in the same one


Data Model
● Keyspace
● Column Family (standard or super)
● Columns & Super Columns
● Keys and column names
Keyspace1: {
users: {
"cb1kenobi": {
"FirstName": "chris",
"LastName": "barber"
}
}
}


Installing & Deploying
Cassandra


Getting Cassandra
● http://cassandra.apache.org/download/
● http://www.apache.org/dist/cassandra/0.6.1/apache-cassandra-0.6.1-bin.tar.gz
● http://www.apache.org/dist/cassandra/0.6.1/apache-cassandra-0.6.1-src.tar.gz
● svn checkout https://svn.apache.org/repos/asf/cassandra/trunk cassandra

●
git clone git://git.apache.org/cassandra.git


Installing Cassandra
su
cd /usr/local
wget http://www.apache.org/dist/cassandra/0.6.1/apache-cassandra-0.6.1-src.tar.gz
tar xzf apache-cassandra-0.6.1-src.tar.gz
mkdir -p /var/log/cassandra
chown -R `whoami` /var/log/cassandra
mkdir -p /var/lib/cassandra
chown -R `whoami` /var/lib/cassandra
cd apache-cassandra-0.6.1-src
ant


Configuration
● Main config file
● conf/storage-conf.xml
● Keyspaces
● Partitioner
● AutoBootstrap
● Authentication method
● Buffer sizes
● Timeouts


Automatically Start Cassanrda
useradd -G cassandra cassandra

<editor of choice> /etc/init.d/cassandra
# paste contents of next slide

chmod +x /etc/init.d/cassandra

# Ubuntu/Debian method:
update-rc.d -f cassandra defaults
# Red Hat/Fedora method: use chkconfig


Automatically Start Cassandra
#!/bin/bash
export JAVA_HOME=/usr/bin/java
export CASSANDRA_HOME=/usr/local/apache-cassandra-0.6.1-src
export CASSANDRA_INCLUDE=$CASSANDRA_HOME/bin/cassandra.in.sh
export CASSANDRA_CONF=$CASSANDRA_HOME/conf/storage-conf.xml
export CASSANDRA_OWNR=cassandra
export PATH=$PATH:$CASSANDRA_HOME/bin
log_file=/var/log/cassandra/stdout
pid_file=/var/run/cassandra/pid_file

if [ ! -f $CASSANDRA_HOME/bin/cassandra -o ! -d $CASSANDRA_HOME ]
then
echo "Cassandra startup: cannot start"
exit 1
fi

mkdir -p /var/run/cassandra
chown cassandra:cassandra /var/run/cassandra

case "$1" in
start)
# Cassandra startup
echo -n "Starting Cassandra: "
su $CASSANDRA_OWNR -c "$CASSANDRA_HOME/bin/cassandra -p $pid_file" > $log_file 2>&1
echo "OK"
;;
stop)
# Cassandra shutdown
echo -n "Shutdown Cassandra: "
su $CASSANDRA_OWNR -c "kill `cat $pid_file`"
echo "OK"
;;
reload|restart)
$0 stop
$0 start
;;
status)
;;
*)
echo "Usage: `basename $0` start|stop|restart|reload"
exit 1
esac

exit 0

Running Cassandra
● Manually start
● bin/cassandra -f
● Command line app
● bin/cassandra-cli --host localhost --port 9160
● Nodetool
● bin/nodetool -h localhost info
20146078924586773365182178806181105130
Load : 274.66 KB
Generation No : 1273183803
Uptime (seconds) : 121
Heap Memory (MB) : 51.84 / 1023.88

● Many more commands: ring, cleanup, cfstats, etc


PHP Clients


PHP Clients
● Thrift
● Pandra (LGPL)
● PHP Cassa – pycassa port
● Simple Cassie (New BSD License)
● Prophet (PHP License)


PHP Thrift Client
● Thrift files ● Thrift generated PHP
● Thrift.php files
● protocol/TBinaryProtocol.php ● thrift --gen php cassandra.thrift
● protocol/TProtocol.php – cassandra_constants.php
● transport/TBufferedTransport.php – Cassandra.php
● transport/TFramedTransport.php – cassandra_types.php
● transport/THttpClient.php ● Use thrift_protocol
● transport/TMemoryBuffer.php native PHP extension
● transport/TNullTransport.php
● transport/TPhpStream.php
● transport/TSocket.php
● transport/TSocketPool.php
● transport/TTransport.php


PHP Thrift Client Example
<?php
$GLOBALS['THRIFT_ROOT'] = './thrift';
require $GLOBALS['THRIFT_ROOT'] . '/Thrift.php';
require $GLOBALS['THRIFT_ROOT'] . '/transport/TSocket.php';
require $GLOBALS['THRIFT_ROOT'] . '/transport/TBufferedTransport.php';
require $GLOBALS['THRIFT_ROOT'] . '/protocol/TBinaryProtocol.php';
require $GLOBALS['THRIFT_ROOT'] . '/packages/cassandra/Cassandra.php';

$socket = new TSocket('127.0.0.1', 9160);
$transport = new TBufferedTransport($socket, 1024, 1024);
$protocol = new TbinaryProtocolAccelerated($transport);
$client = new CassandraClient($protocol);

$transport->open();

$columnPath = new cassandra_ColumnPath();
$columnPath->column_family = 'Standard1';
$columnPath->super_column = null;
$columnPath->column = 'firstname';

$client->insert('Keyspace1', 'mykey', $columnPath, 'Chris', time(),
cassandra_ConsistencyLevel::ONE);

$name = $client->get('Keyspace1', 'mykey', $columnPath, cassandra_ConsistencyLevel::ONE);
var_dump($name);

$transport->close();


Prophet PHP Extension
● C++ PHP Extension
● Built on top of Thrift C library
● Very, very, very far from usable/working/complete
● Goals
● Speed!
● Full API support
● CRUD/ORM magic
● Serialization helper
● Developed for PHP 5.3, Linux, non-threaded (i.e.
FastCGI)
● http://github.com/cb1kenobi/prophet

Cassandra Roadmap


Roadmap 0.7 & Beyond
● SSTable compression
● Live keyspace & column family changes
● Vector clock support
● Truncate support
● Range delete
● byte[] keys
● Memory efficient compactions
● Apache Avro
● Multi-tenant support
* Taken from other presentations


Resources
● Cassandra Wiki
● http://wiki.apache.org/cassandra/
● IRC
● #cassandra on irc.freenode.net
● Cassandra Users Mailing List
● user-subscribe@cassandra.apache.org
● Follow people on Twitter
● @cassandra ● @jericevans
● @spyced ● @riptano
● @b6n


Getting Help

CB1, INC
Web Applications
Open Source Solutions


Thanks!

Questions?
http://twitter.com/cb1inc
http://slideshare.net/cb1kenobi
http://twitter.com/cb1kenobi


Cassandra - Say Goodbye to the Relational Database (5-6-2010)

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