The document discusses scalable PHP web applications using Apache Cassandra. It provides an overview of Cassandra, how it can be used with PHP via Thrift and PhpCassa, and a case study of how a flash deals website was built using Cassandra to handle filtering and querying of millions of deals. Code examples are shown of how the application retrieves deals data from Cassandra based on attributes and location. The presentation concludes with resources for learning more about Cassandra and a call for questions.

1. @akira28
Scalable PHP web
applications with Apache
Cassandra
Andrea De Pirro

2. @akira28
About me
• Co-founder at Yameveo
• 9+ years developing in PHP
• 2+ years experience with Apache Cassandra
• Zend Framework Certified Engineer

3. @akira28
Yameveo
Founded on 2012 in Barcelona, Yameveo is a young,
dynamic and international company specialised in e-
commerce and web applications development
!
!
www.yameveo.com
@Yameveo

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Yameveo Store
Dozens of e-commerce modules
store.yameveo.com

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What we will talk about
• Apache Cassandra
• Data Modeling
• Cassandra & PHP
• Case study

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Apache Cassandra
Apache Cassandra is a massively scalable open source
NoSQL database. Cassandra is perfect for managing
large amounts of structured, semi-structured, and
unstructured data across multiple data centers and the
cloud. Cassandra delivers continuous availability, linear
scalability, and operational simplicity across many
commodity servers with no single point of failure, along
with a powerful dynamic data model designed for
maximum flexibility and fast response times.
Apache Cassandra documentation

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Why Cassandra
• Open Source (enterprise distribution also available)
• Linearly scalable
• Fault-tolerant
• Fully distributed
• Highly performant
• Flexible data model

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Cassandra Uses
• Web analytics
• Web Applications
• Transaction logging
• Data collection
• …

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Architecture

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CAP Theorem
Only two of:!
!
1. Consistency
all nodes see the same data at the same time
2. Availability
the guarantee that every request receives a
response about whether it was successful or
failed
3. Partition Tolerance
the system continues to operate despite
message loss or failure of part of the system

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CAP Theorem

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Architecture
• Ring
• Each node has a unique token and is identical
• Intra-ring communication via “Gossip” protocol
• Tokens range from 0 to 2^127

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Partitioning

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Data Modeling

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Data Model
• Cluster
• Keyspace
• Column Family
• Super Column
• Composite Columns

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Data Model

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Data Model

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Data Modeling Problems
• Neither join nor subquery support
• Limited support for aggregation
• Ordering is done per-partition
• Ordering is specified at table creation time

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Data Modeling
Best Practices
• Don’t think of a relational table
• Model column families around query patterns
• De-normalize and duplicate for read performance
• Storing values in column names is perfectly OK
• Leverage wide rows for ordering, grouping, and
filtering

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Some Numbers

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Some Numbers

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Cassandra & PHP

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Apache Thrift
Thrift is an interface definition language and binary
communication protocol that is used to define and create
services for numerous languages. It is used as a remote
procedure call (RPC) framework and was developed at
Facebook for "scalable cross-language services
development"
Wikipedia

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Apache Thrift

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PhpCassa
• Open Source
• Uses the Thrift protocol
• Compatible with Cassandra 0.7 through 1.2
• Optional C extension for improved performance
https://github.com/thobbs/phpcassa
!
require: “thobbs/phpcassa”: “v1.1.0”

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Examples
Opening Connections!
!
$pool = new ConnectionPool('Keyspace1');
!
Create a column family object!
!
$users = new ColumnFamily($pool, 'Standard1');
$super = new SuperColumnFamily($pool, 'Super1');
!
Inserting!
!
$users->insert('key', array('column1' => 'value1', 'column2' => 'value2'));
!
Querying!
!
$users->get(‘key'); // returns an array
$users->multiget(array('key1', ‘key2')); // returns an array of arrays
!
Removing!
!
$users->remove('key1'); // removes whole row
$users->remove('key1', 'column1'); // removes 'column1'

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Case Study

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Flash Deals website
• 5 Apache servers
• 32 GB of RAM
• 8 CPU
• 6 Cassandra nodes
• 4+ millions visits/month
• 17+ millions pages/month
• 600GB of data

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Requirement
• The client wanted a new way to navigate the
website: deal attributes
• Millions of deals (hundreds new and expiring
everyday)
• Dozens of stores and categories
• Performance is key!

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How We Solved It
• Each day we have new deals, so queries based
on date and attributes
• Leverage Cassandra wide-rows to create
indexes
• Use Cassandra multiGet whenever possible

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Deals CF
RowKey name price attributes …
211
Miyagi
Sushi
29 [21,20,114]
432
Mos Eisley
Cantina
19 [21,20]
12
iPhone 5
32GB
549 [7]
… … …

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Attributes CF
RowKey name keyword
21 Restaurants restaurants
114 Japanese japanese
20 Barcelona barcelona
7 Technology tech

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Cities CF
RowKey name attributeid …
1 Madrid 12
8 Barcelona 20
32 Amsterdam 81

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Urls CF
RowKey attributes city …
/restaurants/barcelona [21] 8
/restaurants/barcelona/japanese [21,114] 8
/tech [7] -
/restaurants [21] -
… … …

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AttributesDeals CF
RowKey 211 432 12 … …
21|20140621 true true -
114|20140621 true - -
20|20140621 true true -
7|20140621 - - true
… … … …

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Code
/**
* List deals action
* eg. /restaurants/barcelona/japanese
*
*/
public function dealsAction()
{
$path = $this->getUrlPath(); // cleaned query string
!
$url = $this->manager->getUrl($path);
$attributes = Zend_Json::decode($url[‘attributes’]);
$cityId = $url[‘city’];
$deals = $this->manager->getDeals($attributes, $cityId);
$this->view->assign(‘deals’, $deals);
…
}
Controller

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Code
/**
* Retrieves the url containing attributes and city infos
*
* @param string $path
* @return array $url
*/
public function getUrl($path)
{
$pool = new ConnectionPool('Keyspace');
$urls = new ColumnFamily($pool, 'Urls');
try {
$url = $urls->get($path);
}
catch (Exception $e) {
…
}
return $url;
}
Manager

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Code
/**
* Retrieves the url containing attributes and city infos
*
* @param array $attributes
* @param int $cityId
* @return array $deals
*/
public function getDeals($attributes, $cityId)
{
$pool = new ConnectionPool('Keyspace');
$dealsCF = new ColumnFamily($pool, ‘Deals’);
if(!empty($cityId) {
$attributes[] = $this->getAttributeIdByCity($cityId);
}
try {
$dealsIds = $this->getDealsIdsByAttributes($attributes);
$deals = $dealsCF->multiget($dealsIds);
}
catch (Exception $e) {
…
}
return $deals;
}
Manager

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Code/**
* Retrieves an array of deals ids given an array of attribute ids
*
* @param array $attributes
* @return array $dealsIds
*/
protected function getDealsIdsByAttributes($attributes)
{
$dealsIds = array();
$dealsGroups = array();
$date = date(‘Ymd’);
$attributesDeals= new ColumnFamily($pool, 'AttributesDeals');
foreach($attributes as $attributeId) {
$attributeKey =“$attributeId|$date";
$dealsGroups[] = array_keys($attributesDeals->get($attributeKey)); // columns!
}
$countGroups = count($dealsGroups);
if($countGroups > 1) {
$dealsIds = call_user_func_array('array_intersect', $dealsGroups);
}
elseif($countGroups == 1) {
$dealsIds = reset($dealsGroups);
}
return $dealsIds;
}
Manager

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Cassandra future (and
present)
• New PHP driver wrapping the C++ driver
• Cassandra 2.0
• CQL 3.0

44. @akira28
Resources
• www.yameveo.com
• http://planetcassandra.org
• https://github.com/thobbs/phpcassa
• http://www.hakkalabs.co/articles/cassandra-
data-modeling-guide

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Resources
• http://www.ebaytechblog.com/2012/07/16/
cassandra-data-modeling-best-practices-part-1/
• http://www.slideshare.net/DataStax/cassandra-
community-webinar-introduction-to-apache-
cassandra-12
• http://www.geroba.com/cassandra/apache-
cassandra-byteorderedpartitioner/

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Questions?

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yameveo@yameveo.com
WE ARE HIRING!

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Dank!
joind.in/10865
lanyrd.com/scxyhk
!
www.yameveo.com
!
@akira28
@Yameveo
!
http://bit.ly/andreadepirro