NYC* Tech Day - New Cassandra Drivers in Depth
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The document discusses new Cassandra drivers that utilize a CQL binary protocol and provide an asynchronous, failover-capable architecture. Key points include the drivers supporting CQL's denormalized data model, request pipelining, notifications, configurable load balancing and retry policies, and downgrading consistency levels automatically if necessary.
![CQL3 Data Model
Timeline Table
user_id tweet_id author body
gmason 1735 phenry Give me liberty or give me death
gmason 1742 gwashington I chopped down the cherry tree
ahamilton 1767 jadams A government of laws, not men
ahamilton 1794 gwashington I chopped down the cherry tree
Timeline Physical Layout
[1735, author] [1735, body] [1742, author] [1742, body]
gmason
gwashington I chopped down the... phenry Give me liberty or give...
[1767, author] [1767, body] [1794, author] [1794, body]
ahamilton
gwashington I chopped down the... jadams A government of laws...
©2012 DataStax 7](https://image.slidesharecdn.com/nyctechday-newcassandradriversindepth-130322112221-phpapp01/85/NYC-Tech-Day-New-Cassandra-Drivers-in-Depth-7-320.jpg)
![LoadBalancingPolicy
public interface LoadBalancingPolicy {
HostDistance distance(Host host);
Iterator<Host> newQueryPlan(Query query);
[...]
}
©2012 DataStax 15](https://image.slidesharecdn.com/nyctechday-newcassandradriversindepth-130322112221-phpapp01/85/NYC-Tech-Day-New-Cassandra-Drivers-in-Depth-15-320.jpg)
![RetryPolicy
public interface RetryPolicy {
RetryDecision onReadTimeout(Query query, ConsistencyLevel cl, [...] );
RetryDecision onWriteTimeout(Query query, ConsistencyLevel cl, [...] );
RetryDecision onUnavailable(Query query, ConsistencyLevel cl, [...] );
public static class RetryDecision {
public static enum Type { RETRY, RETHROW, IGNORE };
private final Type type;
private final ConsistencyLevel retryCL;
[...]
}
}
©2012 DataStax 18](https://image.slidesharecdn.com/nyctechday-newcassandradriversindepth-130322112221-phpapp01/85/NYC-Tech-Day-New-Cassandra-Drivers-in-Depth-18-320.jpg)
NYC* Tech Day - New Cassandra Drivers in Depth
- 1. New Cassandra Drivers in Depth Michaël Figuière @mfiguiere
- 2. Speaker Michaël Figuière @mfiguiere ©2012 DataStax 2
- 3. CQL: the new face of Cassandra • CQL 3 • Simpler Data Model using denormalized Tables • SQL-like query language • Schema definition • CQL Binary Protocol • Introduced in Cassandra 1.2 (CASSANDRA-2478) • Designed for CQL 3 • Opens doors for Streaming, Notifications, ... • Thrift will keep being supported by Cassandra ©2012 DataStax 3
- 4. CQL3 Denormalized Model CQL3 Query Language comes with a new Data Model abstraction made of denormalized, statically defined tables Data duplicated over several tables ©2012 DataStax 4
- 5. CQL3 Data Model Timeline Table user_id tweet_id author body gmason 1735 phenry Give me liberty or give me death gmason 1742 gwashington I chopped down the cherry tree ahamilton 1767 jadams A government of laws, not men ahamilton 1794 gwashington I chopped down the cherry tree Partition Clustering Key Key ©2012 DataStax 5
- 6. CQL3 Data Model Timeline Table user_id tweet_id author body gmason 1735 phenry Give me liberty or give me death gmason 1742 gwashington I chopped down the cherry tree ahamilton 1767 jadams A government of laws, not men ahamilton 1794 gwashington I chopped down the cherry tree CQL CREATE TABLE timeline ( user_id varchar, tweet_id timeuuid, author varchar, body varchar, PRIMARY KEY (user_id, tweet_id)); ©2012 DataStax 6
- 7. CQL3 Data Model Timeline Table user_id tweet_id author body gmason 1735 phenry Give me liberty or give me death gmason 1742 gwashington I chopped down the cherry tree ahamilton 1767 jadams A government of laws, not men ahamilton 1794 gwashington I chopped down the cherry tree Timeline Physical Layout [1735, author] [1735, body] [1742, author] [1742, body] gmason gwashington I chopped down the... phenry Give me liberty or give... [1767, author] [1767, body] [1794, author] [1794, body] ahamilton gwashington I chopped down the... jadams A government of laws... ©2012 DataStax 7
- 8. Current Drivers Architecture CQL API Thrift API OO API DB API Thrift RPC Thrift RPC Client Library CQL Driver * This is a simplified view of drivers architecture. Details vary from one language to another. ©2012 DataStax 8
- 9. New Drivers Architecture DB API CQL API OO API CQL Native Protocol Next Generation Driver * This is a simplified view of drivers architecture. Details vary from one language to another. ©2012 DataStax 9
- 10. DataStax Java Driver • Reference Implementation • Asynchronous architecture based on Netty • Prepared Statements Support • Automatic Fail-over • Node Discovery • Cassandra Tracing Support • Tunable policies • LoadBalancingPolicy • ReconnectionPolicy • ©2012 DataStax RetryPolicy 10
- 11. Request Pipelining Client Cassandra Without Request Pipelining With Client Cassandra Request Pipelining ©2012 DataStax 11
- 12. Notifications Node Client Node Node Without Notifications With Notifications Node Client Node Node ©2012 DataStax 12
- 13. Asynchronous Architecture Node Client Thread Node Client Driver Thread Node Client Thread Node ©2012 DataStax 13
- 14. Asynchronous Architecture Node Client Thread 6 1 Node Client Driver 2 Thread 3 Node 5 4 Client Thread Node ©2012 DataStax 14
- 15. LoadBalancingPolicy public interface LoadBalancingPolicy { HostDistance distance(Host host); Iterator<Host> newQueryPlan(Query query); [...] } ©2012 DataStax 15
- 16. DCAwareRoundRobinPolicy Datacenter A Local nodes are queried first, if non Client Node are available, the request will be sent Client Node to a remote node. Node Client Client Node Client Node Node Client Datacenter B ©2012 DataStax 16
- 17. TokenAwarePolicy Nodes that own a Replica of the data being read or written by the query will be contacted first. Replica Node Node Client Replica Node Node Replica Node ©2012 DataStax 17
- 18. RetryPolicy public interface RetryPolicy { RetryDecision onReadTimeout(Query query, ConsistencyLevel cl, [...] ); RetryDecision onWriteTimeout(Query query, ConsistencyLevel cl, [...] ); RetryDecision onUnavailable(Query query, ConsistencyLevel cl, [...] ); public static class RetryDecision { public static enum Type { RETRY, RETHROW, IGNORE }; private final Type type; private final ConsistencyLevel retryCL; [...] } } ©2012 DataStax 18
- 19. Downgrading Consistency If the requested Consistency Level cannot be reached (QUORUM here), a second request with a lower CL is sent automatically. Node Replica Client Node Replica Node Replica ©2012 DataStax 19
- 20. Connect and Write Cluster cluster = Cluster.builder() .addContactPoints("10.0.0.1", "10.0.0.2") .build(); Session session = cluster.connect("myKeyspace"); session.execute( "INSERT INTO user (user_id, name, email) VALUES (12345, 'johndoe', 'john@doe.com')" ); ©2012 DataStax 20
- 21. Read ResultSet rs = session.execute("SELECT * FROM test"); List<Row> rows = rs.all(); for (Row row : rows) { String userId = row.getString("user_id"); String name = row.getString("name"); String email = row.getString("email"); } ©2012 DataStax 21
- 22. Asynchronous Read ResultSetFuture future = session.executeAsync("SELECT * FROM test"); for (Row row : future.get()) { String userId = row.getString("user_id"); String name = row.getString("name"); String email = row.getString("email"); } ©2012 DataStax 22
- 23. Prepared Statements PreparedStatement ps = session.prepare("SELECT * FROM users WHERE id = ?"); BoundStatement bs = session.execute(ps.bind("123")).one().getInt("age"); bs.setString("k"); int age = session.execute(bs).one().getInt("age"); age = session.execute(ps.bind("123")).one().getInt("age"); ©2012 DataStax 23
- 24. Query Builder String query = "SELECT a,b,"C" FROM foo WHERE a IN (127.0.0.1,127.0.0.3) AND "C"='foo' ORDER BY a ASC,b DESC LIMIT 42;"; Query select = select("a", "b", quote("C")).from("foo") .where(in("a", InetAddress.getByName("127.0.0.1"), InetAddress.getByName("127.0.0.3"))) .and(eq(quote("C"), "foo")) .orderBy(asc("a"), desc("b")) .limit(42); ©2012 DataStax 24
- 25. Object Mapping @Table(name = "user") public class User { public enum Gender { @PartitionKey @EnumValue("m") @Column(name = "user_id") MALE, private String userId; @EnumValue("f") private String name; FEMALE; } private String email; private Gender gender; } ©2012 DataStax 25
- 26. Inheritance @Table(name = "catalog") @Inheritance( @InheritanceValue("tv") subClasses = {Phone.class, TV.class}, public class TV column = "product_type" extends Product { ) public abstract class Product { private float size; } @Column(name = "product_id") private String productId; private float price; private String vendor; private String model; } ©2012 DataStax 26
- 27. Betas now available! https://github.com/datastax/
- 28. Stay Tuned! blog.datastax.com @mfiguiere