Cassandra for PHP developers Introduction to Apache Cassandra Overview of the DataStax PHP driver Bulat Shakirzyanov @avalanche123

Introduction Cassandra Overview

© 2015 DataStax, All Rights Reserved. Datacenter Datacenter Cassandra Topology 3 Node Node Node Node Client Client Node Node Node Node Client Client Cluster

© 2015 DataStax, All Rights Reserved. Datacenter Datacenter Request Coordinator 4 Node Node Node Node Client Client Node Node Coordinator Node Client Client Coordinator node: Forwards requests to corresponding replicas

© 2015 DataStax, All Rights Reserved. Datacenter Row Replica 5 Replica Node Node Replica Client Client Datacenter Node Node Replica Client Client Coordinator Replica node: Stores a slice of total rows of each keyspace

© 2015 DataStax, All Rights Reserved. Token Ring 6 12 1 2 3 4 5 6 7 8 9 10 11

© 2015 DataStax, All Rights Reserved. Token Ring 6 -263 … (+263 - 1) Murmur3 Partitioner

© 2015 DataStax, All Rights Reserved. Token Ring 6 Node 11…12 Node 12…1 Node 1…2 Node 2…3 Node 3…4 Node 4…5 Node 5…6 Node 6…7 Node 7…8 Node 8…9 Node 9…10 Node 10…11 -263 … (+263 - 1) Murmur3 Partitioner

© 2015 DataStax, All Rights Reserved. Keyspaces 7 CREATE KEYSPACE default WITH replication = { 'class': 'SimpleStrategy', 'replication_factor': 3 }

© 2015 DataStax, All Rights Reserved. C* Data Partitioning 8 Keyspace Row token(PK) = 1 RF = 3 Partitioner: Gets a token by hashing the primary key of a row

© 2015 DataStax, All Rights Reserved. C* Replication Strategy 9 Keyspace 1 Row RF = 3 Replication strategy: Determines the first replica for the row token(PK) = 1

© 2015 DataStax, All Rights Reserved. C* Replication Factor 10 Keyspace Row RF = 3 Replication factor: Specifies total number of replicas for each row token(PK) = 1

© 2015 DataStax, All Rights Reserved. Coordinator Node Replica Replica Node 11 Replica Application Consistency Level RF = 3, CL = Quorum

© 2015 DataStax, All Rights Reserved. Coordinator Node Replica Replica Node 11 Replica Application Consistency Level RF = 3, CL = Quorum INSERT

© 2015 DataStax, All Rights Reserved. Coordinator Node Replica Replica Node 11 Replica Application Consistency Level RF = 3, CL = Quorum INSERT

© 2015 DataStax, All Rights Reserved. Coordinator Node Replica Replica Node 11 Replica Application Consistency Level RF = 3, CL = Quorum INSERT

© 2015 DataStax, All Rights Reserved. Coordinator Node Replica Replica Node 11 Replica Application Consistency Level RF = 3, CL = Quorum INSERT

© 2015 DataStax, All Rights Reserved. C* Quorum 12 Keyspace Row RF = 3 token(PK) = 1 floor(RF / 2) + 1

DataStax PHP Driver Smart client for Apache Cassandra

© 2015 DataStax, All Rights Reserved. Installation 14 git clone https://github.com/datastax/php-driver.git cd php-driver pecl install ext/package.xml

© 2015 DataStax, All Rights Reserved. Usage 15 $cluster = Cassandra::cluster() // connects to localhost by default ->build(); $keyspace = 'system'; $session = $cluster->connect($keyspace); // create session, optionally scoped to a keyspace $statement = new Cassandra\SimpleStatement( // also supports prepared and batch statements 'SELECT keyspace_name, columnfamily_name ' . 'FROM schema_columnfamilies' ); $future = $session->executeAsync($statement); // fully asynchronous and easy parallel execution $result = $future->get(); // wait for the result, with an optional timeout foreach ($result as $row) { // results and rows implement Iterator, Countable // ArrayAccess printf("The keyspace %s has a table %s\n", $row['keyspace_name'], $row['columnfamily_name']); }

© 2015 DataStax, All Rights Reserved. Usage 16 $cluster = Cassandra::cluster() // connects to localhost by default ->build(); $keyspace = 'system'; $session = $cluster->connect($keyspace); // create session, optionally scoped to a keyspace $statement = new Cassandra\SimpleStatement( // also supports prepared and batch statements 'SELECT keyspace_name, columnfamily_name ' . 'FROM schema_columnfamilies' ); $future = $session->executeAsync($statement); // fully asynchronous and easy parallel execution $result = $future->get(); // wait for the result, with an optional timeout foreach ($result as $row) { // results and rows implement Iterator, Countable // ArrayAccess printf("The keyspace %s has a table %s\n", $row['keyspace_name'], $row['columnfamily_name']); }

© 2015 DataStax, All Rights Reserved. Usage 17 $cluster = Cassandra::cluster() // connects to localhost by default ->build(); $keyspace = 'system'; $session = $cluster->connect($keyspace); // create session, optionally scoped to a keyspace $statement = new Cassandra\SimpleStatement( // also supports prepared and batch statements 'SELECT keyspace_name, columnfamily_name ' . 'FROM schema_columnfamilies' ); $future = $session->executeAsync($statement); // fully asynchronous and easy parallel execution $result = $future->get(); // wait for the result, with an optional timeout foreach ($result as $row) { // results and rows implement Iterator, Countable // ArrayAccess printf("The keyspace %s has a table %s\n", $row['keyspace_name'], $row['columnfamily_name']); }

© 2015 DataStax, All Rights Reserved. Usage 18 $cluster = Cassandra::cluster() // connects to localhost by default ->build(); $keyspace = 'system'; $session = $cluster->connect($keyspace); // create session, optionally scoped to a keyspace $statement = new Cassandra\SimpleStatement( // also supports prepared and batch statements 'SELECT keyspace_name, columnfamily_name ' . 'FROM schema_columnfamilies' ); $future = $session->executeAsync($statement); // fully asynchronous and easy parallel execution $result = $future->get(); // wait for the result, with an optional timeout foreach ($result as $row) { // results and rows implement Iterator, Countable // ArrayAccess printf("The keyspace %s has a table %s\n", $row['keyspace_name'], $row['columnfamily_name']); }

© 2015 DataStax, All Rights Reserved. Usage 19 $cluster = Cassandra::cluster() // connects to localhost by default ->build(); $keyspace = 'system'; $session = $cluster->connect($keyspace); // create session, optionally scoped to a keyspace $statement = new Cassandra\SimpleStatement( // also supports prepared and batch statements 'SELECT keyspace_name, columnfamily_name ' . 'FROM schema_columnfamilies' ); $future = $session->executeAsync($statement); // fully asynchronous and easy parallel execution $result = $future->get(); // wait for the result, with an optional timeout foreach ($result as $row) { // results and rows implement Iterator, Countable // ArrayAccess printf("The keyspace %s has a table %s\n", $row['keyspace_name'], $row['columnfamily_name']); }

© 2015 DataStax, All Rights Reserved. Usage 20 $cluster = Cassandra::cluster() // connects to localhost by default ->build(); $keyspace = 'system'; $session = $cluster->connect($keyspace); // create session, optionally scoped to a keyspace $statement = new Cassandra\SimpleStatement( // also supports prepared and batch statements 'SELECT keyspace_name, columnfamily_name ' . 'FROM schema_columnfamilies' ); $future = $session->executeAsync($statement); // fully asynchronous and easy parallel execution $result = $future->get(); // wait for the result, with an optional timeout foreach ($result as $row) { // results and rows implement Iterator, Countable // ArrayAccess printf("The keyspace %s has a table %s\n", $row['keyspace_name'], $row['columnfamily_name']); }

© 2015 DataStax, All Rights Reserved. Usage 21 $cluster = Cassandra::cluster() // connects to localhost by default ->build(); $keyspace = 'system'; $session = $cluster->connect($keyspace); // create session, optionally scoped to a keyspace $statement = new Cassandra\SimpleStatement( // also supports prepared and batch statements 'SELECT keyspace_name, columnfamily_name ' . 'FROM schema_columnfamilies' ); $future = $session->executeAsync($statement); // fully asynchronous and easy parallel execution $result = $future->get(); // wait for the result, with an optional timeout foreach ($result as $row) { // results and rows implement Iterator, Countable // ArrayAccess printf("The keyspace %s has a table %s\n", $row['keyspace_name'], $row['columnfamily_name']); }

Asynchronous Execution IO Reactor and Request Pipelining

© 2015 DataStax, All Rights Reserved. Asynchronous Core 23 Application Thread Business Logic Driver Background Thread IO Reactor

© 2015 DataStax, All Rights Reserved. Request Pipelining 24 Client Without Request Pipelining Server Client Server With Request Pipelining 1 2 2 3 1 3 1 2 3 1 2 3

© 2015 DataStax, All Rights Reserved. Parallel execution 25 $data = array( array(41, 'Sam'), array(35, 'Bob') ); $session = $cluster->connect("mykeyspace"); $statement = $session->prepare("UPDATE users SET age = ? WHERE user_name = ?"); $futures = array(); // execute all statements in background foreach ($data as $arguments) { $options = new ExecutionOptions(array('arguments' => $arguments)); $futures[]= $session->executeAsync($statement, $options); } // wait for all statements to complete foreach ($futures as $future) { // we will not wait for each result for more than 5 seconds $future->get(5); }

© 2015 DataStax, All Rights Reserved. Parallel execution 26 $data = array( array(41, 'Sam'), array(35, 'Bob') ); $session = $cluster->connect("mykeyspace"); $statement = $session->prepare("UPDATE users SET age = ? WHERE user_name = ?"); $futures = array(); // execute all statements in background foreach ($data as $arguments) { $options = new ExecutionOptions(array('arguments' => $arguments)); $futures[]= $session->executeAsync($statement, $options); } // wait for all statements to complete foreach ($futures as $future) { // we will not wait for each result for more than 5 seconds $future->get(5); }

© 2015 DataStax, All Rights Reserved. Parallel execution 27 $data = array( array(41, 'Sam'), array(35, 'Bob') ); $session = $cluster->connect("mykeyspace"); $statement = $session->prepare("UPDATE users SET age = ? WHERE user_name = ?"); $futures = array(); // execute all statements in background foreach ($data as $arguments) { $options = new ExecutionOptions(array('arguments' => $arguments)); $futures[]= $session->executeAsync($statement, $options); } // wait for all statements to complete foreach ($futures as $future) { // we will not wait for each result for more than 5 seconds $future->get(5); }

© 2015 DataStax, All Rights Reserved. Parallel execution 28 $data = array( array(41, 'Sam'), array(35, 'Bob') ); $session = $cluster->connect("mykeyspace"); $statement = $session->prepare("UPDATE users SET age = ? WHERE user_name = ?"); $futures = array(); // execute all statements in background foreach ($data as $arguments) { $options = new ExecutionOptions(array('arguments' => $arguments)); $futures[]= $session->executeAsync($statement, $options); } // wait for all statements to complete foreach ($futures as $future) { // we will not wait for each result for more than 5 seconds $future->get(5); }

Load Balancing Routing and Failover

© 2015 DataStax, All Rights Reserved. Application Driver Load Balancing 30 Application Thread Node Pool Session Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Load Balancing Policy

© 2015 DataStax, All Rights Reserved. Application Driver Load Balancing 30 Application Thread Node Pool Session Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Load Balancing Policy

© 2015 DataStax, All Rights Reserved. Application Driver Load Balancing 30 Application Thread Node Pool Session Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Load Balancing Policy

© 2015 DataStax, All Rights Reserved. Datacenter Datacenter DataCenter Aware Balancing 31 Node Node Node Client Node Node Node Client Client Client Client Client Local nodes are queried first, if non are available, the request could be sent to a remote node.

© 2015 DataStax, All Rights Reserved. Token Aware Balancing 32 Route request directly to Replicas Node Node Replica Node Client Replica Replica Uses prepared statement metadata to get the token

© 2015 DataStax, All Rights Reserved. Latency Aware Balancing 33 Route requests to the fastest nodes Client Tracks response times for each node

Fault Tolerance Failures and Error Handling

© 2015 DataStax, All Rights Reserved. Fault Tolerance 35 Coordinator Node Replica Replica Replica Node Business Logic Driver Application

© 2015 DataStax, All Rights Reserved. 36 Coordinator Node Replica Replica Replica Node Business Logic Driver Application Invalid Requests Network Timeouts Server Errors Possible Failures

© 2015 DataStax, All Rights Reserved. Application Driver Automatic Retry of Server Errors 37 Application Thread Node Pool Session Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Load Balancing Policy

© 2015 DataStax, All Rights Reserved. Application Driver Automatic Retry of Server Errors 37 Application Thread Node Pool Session Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Load Balancing Policy

© 2015 DataStax, All Rights Reserved. Application Driver Automatic Retry of Server Errors 37 Application Thread Node Pool Session Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Load Balancing Policy

© 2015 DataStax, All Rights Reserved. 38 Coordinator Node Replica Replica Replica Node Business Logic Driver Application Unreachable Consistency

© 2015 DataStax, All Rights Reserved. Coordinator Node Replica Replica Node 39 Replica Business Logic Driver Application Read / Write Timeout Error

© 2015 DataStax, All Rights Reserved. Coordinator Node Replica Replica Node 39 Replica Business Logic Driver Application Read / Write Timeout Error

© 2015 DataStax, All Rights Reserved. Coordinator Node Replica Replica Node 39 Replica Business Logic Driver Application Read / Write Timeout Error read / write timeout

© 2015 DataStax, All Rights Reserved. 40 Coordinator Node Replica Replica Replica Node Business Logic Driver Application Unavailable Error

© 2015 DataStax, All Rights Reserved. 40 Coordinator Node Replica Replica Replica Node Business Logic Driver Application Unavailable Error unavailable

© 2015 DataStax, All Rights Reserved. Other • Persistent Sessions • Security • Datatypes 41

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