Cassandra Drivers and Tools

@doanduyhai

Cassandra Java Driver & Tool DuyHai DOAN, Technical Advocate

Cassandra Drivers Architecture!

Architecture!Policies!

Java driver API!

@doanduyhai

Drivers list!

3

•  Java •  C# •  Python •  Node.js •  Ruby (1.0.0.rc1) •  C++ (beta) •  ODBC (beta) •  Clojure (community) •  Go (community) •  PHP (to be announced)

@doanduyhai

Connection pooling!

4

n2

n3

n4

Driver

Pool1

Pool2

Pool3

Client Thread1

Client Thread2

Client Thread3

@doanduyhai

Connection pooling!

5

n2

n3

n4

Driver

Pool1

Pool2

Pool3

Client Thread1

Client Thread2

Client Thread3

1

2 3

4 5

6

@doanduyhai

Request Pipelining!

6

Client Cassandra

@doanduyhai

Request Pipelining!

7

Client Cassandra

StreamID

StreamID

@doanduyhai

Nodes Discovery!

8

n2

n3

n4

n5

n6

n7

n8

n1 Driver

Control Connection

@doanduyhai

Round Robin Load Balancing!

9

n2

n3

n4

n5

n6

n7

n8

n1 Client 1

2 3

4

@doanduyhai

DC Aware Load Balancing!

10

Client1 DC1

DC2 Client2

⤫

@doanduyhai

DC Aware Load Balancing!

11

Client1 DC1

DC2 Client2

⤫

@doanduyhai

Token Aware Load Balancing!

12

n2

n3

n4

n5

n6

n7

n8

n1 Client

1

2

3

⤫

@doanduyhai

Combining Load Balancing Policies!

13

Load Balancing Policy

Round Robin DC Aware Round Robin

Token Aware

extends

wraps

Default config

@doanduyhai

Automatic Failover!

14

n2

n3

n4

Driver

Pool1

Pool2

Pool3

Client Thread

⤫

1

2 3

4 5

6 7 8

@doanduyhai

Other policies!

15

Retry policy •  write/read timeout •  node unavailable Reconnection policy •  constant schedule •  exponential schedule

@doanduyhai

Statements!

16

Plain statement •  convenient, one-off query •  plain string ☞ parsing overhead

INSERT INTO user(login, name, age) VALUES(‘jdoe’, ‘John DOE’, 33)’;

@doanduyhai

Statements!

17

Prepared statements •  avoid parsing overhead •  query structure should be known ahead of time •  bound values •  named parameters

INSERT INTO user(login, name, age) VALUES(?, ?, ?)’;

INSERT INTO user(login, name, age) VALUES(:login, :name, :age)’;

@doanduyhai

Statements!

18

Parameterized statements •  same as plain statement •  pass bound values as bytes ☞ avoid ser/deser of values

INSERT INTO user(login, name, age) VALUES(?, ?, ?)’;

@doanduyhai

Java Driver!

19

Reference implementation Base on asynchronous Netty library Configurable policies Query tracing support Client-node compression & SSL

@doanduyhai

Maven dependency!

20

<dependency> <groupId>com.datastax.cassandra</groupId> <artifactId>cassandra-driver-core</artifactId> <version>2.1.1</version> </dependency>

depends on Netty, Guava, Metrics

Available on Maven Central

@doanduyhai

Connect and Write!

21

Cluster cluster = Cluster.builder() .addContactPoints("127.0.0.1", “another-host").build();

seed nodes (IP or DNS name)

Session session = cluster.connect("my_keyspace");

session.execute("INSERT INTO user (user_id, name, email) VALUES (12345, 'johndoe', '[email protected]’)");

@doanduyhai

Configuration!

22

Cluster cluster = Cluster.builder() .addContactPoints("127.0.0.1", “another-host") .withLoadBalancingPolicy(new DCAwareRoundRobinPolicy("DC1") .withRetryPolicy(DowngradingConsistencyRetryPolicy.INSTANCE) .withReconnectionPolicy(new ConstantReconnectionPolicy(1000)) .build();

@doanduyhai

Read!

23

ResultSet resultSet = session.execute("SELECT * FROM user");

List<Row> rows = resultSet.all();

for (Row row : rows) { Long userId = row.getLong("user_id"); String name = row.getString("name"); String email = row.getString("email"); }

Stateless ☞ thread-safe

@doanduyhai 24

Asynchronous Read!

ResultSetFuture future = session.executeAsync("SELECT * FROM user");

ResultSet resultSet = future.get(); //blocking call

List<Row> rows = resultSet.all();

for (Row row : rows) { Long userId = row.getLong("user_id"); String name = row.getString("name"); String email = row.getString("email"); }

@doanduyhai 25

Asynchronous Read with CallBack!

ResultSetFuture future = session.executeAsync("SELECT * FROM user");

future.addListener(new Runnable() { public void run() { // Process the results here } }, executor);

executor = Executors .newCachedThreadPool(); or

executor = Executors .sameThreadExecutor();

@doanduyhai 26

Query Builder!

Query query = QueryBuilder .select() .all() .from( "my_keyspace", "user") .where(eq("login", "jdoe"));

query.setConsistencyLevel(ConsistencyLevel.ONE);

ResultSet rs = session.execute(query);

@doanduyhai

Java Driver Object Mapper!

27

•  simple mapper

•  KISS

•  annotations à-la JPA (but no JPA dependencies)

•  templating system à-la Spring Data

@doanduyhai


28

@Table(keyspace = "mapper_module", name = "users") public class User {

@PartitionKey private String login;

private String name; // getters and setters omitted... }

Mapping

@doanduyhai


29

MappingManager manager = new MappingManager(session); Mapper mapper = manager.mapper(User.class);

User user = mapper.get("[email protected]");

mapper.saveAsync(new User("[email protected]"));

mapper.delete("[email protected]");

Usage

@doanduyhai


30

@Accessor interface UserAccessor { @Query("SELECT * FROM users LIMIT :max") Result<User> firstNUsers(@Param("max") int limit); }

Accessors (SpringData template-like) definition

@doanduyhai


31

Accessors usage

UserAccessor accessor = manager.createAccessor(UserAccessor.class); List<User> users = accessor.firstNUsers(10).all(); for (User user : users) { System.out.println( profile.getAddress().getZip() ); }

@doanduyhai

Old manual paging!

32

Some time you need to fetch all table content Manual paging:

SELECT * FROM users WHERE token(login) >= token(<last_fetched_login>) LIMIT 100;

@doanduyhai

New automatic paging!

33

n2

n3

n4

n5

n6

n7

n8

n1 Driver

Query

Page 1 + paging state 1

@doanduyhai


34

n2

n3

n4

n5

n6

n7

n8

n1 Driver

Query


@doanduyhai


35

Paging state ≈ stateless cookie Resilient to node failure

@doanduyhai

Paging during node failure!

36

n2

n3

n4

n5

n6

n7

n8

n1 Driver

Query


@doanduyhai

Paging during node failure!

37

n2

n3

n4

n5

n6

n7

n8

n1 Driver

Query


⤫

Q & R

! " !

Dev Center demo

@doanduyhai Company Confidential 40

Training Day | December 3rd Beginner Track •  Introduction to Cassandra •  Introduction to Spark, Shark, Scala and

Cassandra

Advanced Track •  Data Modeling •  Performance Tuning

Conference Day | December 4th Cassandra Summit Europe 2014 will be the single largest gathering of Cassandra users in Europe. Learn how the world's most successful companies are transforming their businesses and growing faster than ever using Apache Cassandra. http://bit.ly/cassandrasummit2014

Thank You @doanduyhai

[email protected]

https://academy.datastax.com/

Cassandra Drivers and Tools

Technology

Transcript of Cassandra Drivers and Tools