Personal Journey

[root@cassandra1 /]# nodetool status Datacenter: 70 ============== Status=Up/Down |/ State=Normal/Leaving/Joining/Moving — Address Load Tokens Owns (effective) Host ID Rack UN 10.70.0.136 66.55 KB 256 50.2% eab68af1-4c3a-448a-b64a-89432abbe13f 0 DN 10.70.0.137 96.67 KB 1 0.3% ca11bb3d-a171-49c9-a39b-d1b802c5a9d8 0 DN 10.70.0.138 80.98 KB 256 49.5% ab54aa7d-ad0a-4bf7-99e4-2d4465c64706 0 [default@unknown] use demodb1; Authenticated to keyspace: demodb1 [default@demodb1] GET users[utf8(‘bobbyjo’)][utf8(‘full_name’)]; => (name=full_name, value=Robert Jones, timestamp=1382458230649000) Elapsed time: 56 msec(s). Let’s turn down node 1 and 2 (.136 and .137). In this case connect to node 3 and you can’t get data on node 1:

# cassandra-cli -host 10.70.0.138 -port 9160
[default@unknown] use demodb1;
Authenticated to keyspace: demodb1
[default@demodb1] GET users[utf8('bobbyjo')][utf8('full_name')];
null
UnavailableException()
at org.apache.cassandra.thrift.Cassandra$get_result.read(Cassandra.java:6608)
at org.apache.thrift.TServiceClient.receiveBase(TServiceClient.java:78)
at org.apache.cassandra.thrift.Cassandra$Client.recv_get(Cassandra.java:556)
at org.apache.cassandra.thrift.Cassandra$Client.get(Cassandra.java:541)
at org.apache.cassandra.cli.CliClient.executeGet(CliClient.java:729)
at org.apache.cassandra.cli.CliClient.executeCLIStatement(CliClient.java:216)
at org.apache.cassandra.cli.CliMain.processStatementInteractive(CliMain.java:213)
at org.apache.cassandra.cli.CliMain.main(CliMain.java:339)
[default@demodb1] GET users[utf8('bobbyjo')][utf8('full_name')];
null

Let’s add data on node 3 (.138):

SET users['capache']['full_name']='Cassandra Apache';
SET users['capache']['email']='capache@gmail.com';
SET users['capache']['state']='HS';
SET users['capache']['gender']='F';
SET users['capache']['birth_year']='1970';
GET users[utf8('capache')][utf8('full_name')];
=> (name=full_name, value=Cassandra Apache, timestamp=1382527239265000)
Elapsed time: 58 msec(s).

Turn node 1(.136) back on:

# cassandra-cli
Connected to: "My Cassandra Cluster" on 127.0.0.1/9160
Welcome to Cassandra CLI version 1.2.10
[default@unknown] use demodb1;
Authenticated to keyspace: demodb1
[default@demodb1] GET users[utf8('bobbyjo')][utf8('full_name')];
=> (name=full_name, value=Robert Jones, timestamp=1382458230649000)
Elapsed time: 94 msec(s).
[default@demodb1] GET users[utf8('capache')][utf8('full_name')];
=> (name=full_name, value=Cassandra Apache, timestamp=1382527239265000)
Elapsed time: 8.11 msec(s).

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Install Java

Setup DataStax repo

yum install dsc12

Examples: 3 nodes: 10.70.0.136 (seed), 10.70.0.137 and 10.70.0.138

Stop Cassandra:
$ sudo service cassandra stop
Clear the data (not necessary for first run):
$ sudo rm -rf /var/lib/cassandra/*

vi /etc/cassandra/conf/cassandra.yaml

cluster_name: 'My Cassandra Cluster'
num_tokens: 256
seed_provider:
- class_name: org.apache.cassandra.locator.SimpleSeedProvider
parameters:
- seeds: "10.70.0.136"
listen_address: 10.70.0.136
rpc_address: 0.0.0.0
endpoint_snitch: RackInferringSnitch

Listen_address is the IP address of the node, change listen_address with 10.70.0.137 and 10.70.0.138 for node 2 and 3. On each server, run one by one:

service cassandra start

Check status:

root@cassandra1 /]# nodetool status
Datacenter: 70
==============
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
-- Address Load Tokens Owns Host ID Rack
UN 10.70.0.137 120.53 KB 1 0.3% ca11bb3d-a171-49c9-a39b-d1b802c5a9d8 0
UN 10.70.0.138 48.45 KB 256 49.5% ab54aa7d-ad0a-4bf7-99e4-2d4465c64706 0
UN 10.70.0.136 33.99 KB 256 50.2% eab68af1-4c3a-448a-b64a-89432abbe13f 0

To use the database, reference: http://www.datastax.com/docs/0.8/dml/using_cli

$ cassandra-cli -host localhost -port 9160

or just:

# cassandra-cli
Connected to: "My Cassandra Cluster" on 127.0.0.1/9160
Welcome to Cassandra CLI version 1.2.10

Type 'help;' or '?' for help.
Type 'quit;' or 'exit;' to quit.

[default@unknown] CREATE KEYSPACE demodb1
... with placement_strategy = 'org.apache.cassandra.locator.SimpleStrategy'
... and strategy_options = [{replication_factor:1}];
WARNING: [{}] strategy_options syntax is deprecated, please use {}
49b9ea34-770f-3f98-ad2c-bf6b40814ab8

[default@unknown] use demodb1;

CREATE COLUMN FAMILY users
WITH comparator = UTF8Type
AND key_validation_class=UTF8Type
AND column_metadata = [
{column_name: full_name, validation_class: UTF8Type}
{column_name: email, validation_class: UTF8Type}
{column_name: state, validation_class: UTF8Type}
{column_name: gender, validation_class: UTF8Type}
{column_name: birth_year, validation_class: LongType}
];

SET users['bobbyjo']['full_name']='Robert Jones';
SET users['bobbyjo']['email']='bobjones@gmail.com';
SET users['bobbyjo']['state']='TX';
SET users['bobbyjo']['gender']='M';
SET users['bobbyjo']['birth_year']='1975';

[default@demodb1] GET users[utf8('bobbyjo')][utf8('full_name')];
=> (name=full_name, value=Robert Jones, timestamp=1382458230649000)

The easiest way to use Cassandra, is using cqlsh, example:

cqlsh> use demodb1;
cqlsh:demodb1>  select * from users;

 key     | birth_year | email              | full_name        | gender | state
---------+------------+--------------------+------------------+--------+-------
 capache |       1970 |  capache@gmail.com | Cassandra Apache |      F |    HS
 bobbyjo |       1975 | bobjones@gmail.com |     Robert Jones |      M |    TX

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