Cassandra

The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.

Apache Cassandra is an open source NoSQL distributed database trusted by thousands of companies for scalability and high availability without compromising performance.

Data modeling approach Because Cassandra uses this single table-single query approach, queries can perform faster. Data in Cassandra is often arranged as one query per table, and data is repeated in many tables, a process known as denormalization.

Slackbuild

   1 cd /tmp
   2 wget  http://slackbuilds.org/slackbuilds/14.1/system/apache-cassandra.tar.gz
   3 tar xvzf apache-cassandra.tar.gz
   4 wget http://archive.apache.org/dist/cassandra/2.0.7/apache-cassandra-2.0.7-bin.tar.gz
   5 ./apache-cassandra.SlackBuild 
   6 installpkg /tmp/apache-cassandra-2.0.7-noarch-1_SBo.tgz

Node up

   1 useradd cassandra
   2 mkdir /home/cassandra
   3 cd /home/cassandra
   4 chown cassandra . -R
   5 mkdir /var/lib/cassandra
   6 cd /var/lib/cassandra
   7 chown cassandra . -R
   8 mkdir /var/log/cassandra
   9 cd /var/log/cassandra
  10 chown cassandra . -R
  11 JAVA_HOME=/opt/java /opt/apache-cassandra/bin/cassandra -f

cqlsh

http://wiki.apache.org/cassandra/GettingStarted

   1 bin/cqlsh

CREATE KEYSPACE mykeyspace WITH REPLICATION = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };
describe keyspaces;
USE mykeyspace;
CREATE TABLE users (  user_id int PRIMARY KEY,  fname text,  lname text );
INSERT INTO users (user_id,  fname, lname)  VALUES (1745, 'john', 'smith');
INSERT INTO users (user_id,  fname, lname)  VALUES (1744, 'john', 'doe');
INSERT INTO users (user_id,  fname, lname)  VALUES (1746, 'john', 'smith');
describe tables;
SELECT * FROM users;
desc table users;
CREATE INDEX ON users (lname);
desc table users;
SELECT * FROM users WHERE lname = 'smith';

Python sample app

http://datastax.github.io/python-driver/getting_started.html

   1 cd /tmp/
   2 wget http://slackbuilds.org/slackbuilds/14.1/libraries/libev.tar.gz
   3 tar xvzf libev.tar.gz 
   4 cd libev
   5 wget http://dist.schmorp.de/libev/Attic/libev-4.15.tar.gz
   6 ./libev.SlackBuild 
   7 installpkg /tmp/libev-4.15-i486-2_SBo.tgz
   8 easy_install pip # if not installed
   9 pip install cassandra-driver
  10 pip install blist

python3 cass.py

   1 from cassandra.cluster import Cluster
   2 
   3 cluster = Cluster(['127.0.0.1'])
   4 session = cluster.connect('mykeyspace')
   5 rows = session.execute('SELECT  user_id , fname , lname FROM users')
   6 for user_row in rows:
   7     print('%d %s %s'%( user_row.user_id, user_row.fname, user_row.lname) )

python3 asyncCass.py

   1 import time
   2 from cassandra.cluster import Cluster
   3 
   4 def sucessHandler(rows):
   5     print('Received data !')
   6     try:
   7         for user_row in rows:
   8             print('>>> %d %s %s'%( user_row.user_id, user_row.fname, user_row.lname) )
   9     except Exception as ex:
  10         print(ex) 
  11 
  12 def errorHandler(exception):
  13     print(exception) 
  14 
  15 if __name__=='__main__':
  16     cluster = Cluster(['127.0.0.1'])
  17     session = cluster.connect('mykeyspace')
  18     futurex = session.execute_async('SELECT  user_id , fname , lname FROM users')
  19     futurex.add_callbacks(sucessHandler,errorHandler)
  20     print('Wait 3 seconds ...')
  21     time.sleep(3)

Python types conversion

http://datastax.github.io/python-driver/getting_started.html

Java types conversion

http://www.datastax.com/documentation/developer/java-driver/2.0/java-driver/reference/javaClass2Cql3Datatypes_r.html

Export and import schema

   1 echo -e "use schema;\nDESCRIBE KEYSPACE;\n" | cqlsh  CassandraHost > mySchema.cdl
   2 cqlsh  CassandraNEWhost -f mySchema.cdl