hallelujah-cassandra-cql

=Cassandra The Apache Cassandra Project (http://cassandra.apache.org) develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.

=CQL Cassandra originally went with a Thrift RPC-based API as a way to provide a common denominator that more idiomatic clients could build upon independently. However, this worked poorly in practice: raw Thrift is too low-level to use productively, and keeping pace with new API methods to support (for example) indexes in 0.7 or distributed counters in 0.8 is too much for many maintainers.

CQL, the Cassandra Query Language, addresses this by pushing all implementation details to the server; all the client has to know for any operation is how to interpret "resultset" objects. So adding a feature like counters just requires teaching the CQL parser to understand "column + N" notation; no client-side changes are necessary.

(CQL Specification: https://github.com/apache/cassandra/blob/trunk/doc/cql/CQL.textile)

=Quick Start

==Establishing a connection

Defaults to the system keyspace

db = CassandraCQL::Database.new('127.0.0.1:9160')

Specifying a keyspace

db = CassandraCQL::Database.new('127.0.0.1:9160', {:keyspace => 'keyspace1'})

Specifying more than one seed node

db = CassandraCQL::Database.new(['127.0.0.1:9160','127.0.0.2:9160'])

==Creating a Keyspace

Creating a simple keyspace with replication factor 1

db.execute("CREATE KEYSPACE keyspace1 WITH strategy_class='org.apache.cassandra.locator.SimpleStrategy' AND strategy_options:replication_factor=1") db.execute("USE keyspace1")

==Creating a Column Family

Creating a column family with a single validated column

db.execute("CREATE COLUMNFAMILY users (id varchar PRIMARY KEY, email varchar)")

Create an index on the name

db.execute("CREATE INDEX users_email_idx ON users (email)")

==Inserting into a Column Family

Insert without bound variables

db.execute("INSERT INTO users (id, email) VALUES ('kreynolds', '[e-mail]')")

Insert with bound variables

db.execute("INSERT INTO users (id, email) VALUES (?, ?)", 'kway', '[e-mail]')

==Updating a Column Family

Update

db.execute("UPDATE users SET email=? WHERE id=?", '[e-mail]', 'kreynolds')

==Selecting from a Column Family

Select all

db.execute("SELECT * FROM users").fetch { |row| puts row.to_hash.inspect } {"id"=>"kway", "email"=>"[e-mail]"} {"id"=>"kreynolds", "email"=>"[e-mail]"}

Select just one user by id

db.execute("SELECT * FROM users WHERE id=?", 'kreynolds').fetch { |row| puts row.to_hash.inspect } {"id"=>"kreynolds", "email"=>"[e-mail]"}

Select just one user by indexed column

db.execute("SELECT * FROM users WHERE email=?", '[e-mail]').fetch { |row| puts row.to_hash.inspect } {"id"=>"kreynolds", "email"=>"[e-mail]"}

==Deleting from a Column Family

Delete the swarthy bastard Kevin

db.execute("DELETE FROM users WHERE id=?", 'kway')