sudo yum install jna

sudo vim /etc/yum.repos.d/datastax.repo

[datastax]
name = DataStax Repo for Apache Cassandra
baseurl = http://rpm.datastax.com/community
enabled = 1
gpgcheck = 0

sudo yum install dsc20

sudo service cassandra start

sudo service cassandra status

cqlsh

See: https://www.liquidweb.com/kb/how-to-install-cassandra-on-centos-6/

== CQL ==

./cqlsh

-- "show keyspaces" equivalent select * from system.schema_keyspaces;

-- replication strategy: http://www.datastax.com/docs/1.0/cluster_architecture/replication CREATE KEYSPACE twissandra WITH replication = {'class': 'SimpleStrategy', 'replication_factor' : 3};

USE twissandra;

-- data types: http://www.datastax.com/docs/1.1/references/cql/cql_data_types CREATE TABLE users ( username text PRIMARY KEY, password text); CREATE TABLE following ( username text, followed text, PRIMARY KEY(username, followed));

CREATE TABLE followers ( username text, following text, PRIMARY KEY(username, following));

-- uuid - 100 nanoseconds till 1582 + MAC adress, more granular than unixtimestamp, globally unique CREATE TABLE tweets ( tweetid uuid PRIMARY KEY, username text, body text);

-- Materialized view of the tweets - user's timeline -- Think in terms of your queries - don't be afraid of duplication (space is cheap) -- Go wide - rows can have 2 billion columns -- P.S. What you see is not what you get (c) -- http://johnsanda.blogspot.co.uk/2012/10/why-i-am-ready-to-move-to-cql-for.html CREATE TABLE timeline ( username text, created_by text, tweetid timeuuid, body text, PRIMARY KEY(username, tweetid) );

-- Denormalized view of userline (their tweets) CREATE TABLE userline ( username text, tweetid timeuuid, body text, PRIMARY KEY(username, tweetid) );

-- TTL allows to delete old values (eg. older than 24h) INSERT INTO users (username, password) VALUES ('jsmith', 'changeme') USING TTL 86400;

SELECT password FROM users WHERE username = 'jsmith';

ALTER TABLE users ADD country varchar; CREATE INDEX country_key ON users (country);

INSERT INTO users (username, password, country) VALUES ('ted', 'changeme', 'UK'); INSERT INTO users (username, password, country) VALUES ('paul', 'changeme', 'US');

SELECT * FROM users WHERE country='UK';

-- Add testing data (notice the denormalisation) INSERT INTO following (username, followed) VALUES ('jsmith', 'ted'); INSERT INTO following (username, followed) VALUES ('jsmith', 'paul'); INSERT INTO following (username, followed) VALUES ('paul', 'ted');

INSERT INTO followers (username, following) VALUES ('paul', 'jsmith'); INSERT INTO followers (username, following) VALUES ('ted', 'jsmith'); INSERT INTO followers (username, following) VALUES ('ted', 'paul');

-- Given a username, gets the usernames of the people that the user is following. SELECT followed FROM following WHERE username = 'jsmith';

-- Given a username, gets the usernames of the people following that user SELECT following FROM followers WHERE username = 'ted';

-- Add some tweets INSERT INTO tweets ( tweetid, username, body ) VALUES ( 60780342-90fe-11e2-8823-0026c650d722, 'jsmith', 'victory is mine!' );

INSERT INTO userline ( tweetid, username, body ) VALUES ( 60780342-90fe-11e2-8823-0026c650d722, 'jsmith', 'victory is mine!' );

-- add the same tweet into all followers timelines INSERT INTO timeline ( tweetid, username, created_by, body ) VALUES ( 60780342-90fe-11e2-8823-0026c650d722, 'paul', 'jsmith', 'victory is mine!' );

-- Given a username, get their tweet timeline (tweets from people they follow). SELECT tweetid, created_by, body FROM timeline WHERE username = 'paul' ORDER BY tweetid DESC LIMIT 10;

-- Given a username, get their userline (their tweets) SELECT tweetid, body FROM userline WHERE username = 'jsmith' ORDER BY tweetid DESC LIMIT 20;