README.md

Cassava

An unopinionated Cassandra client built on top of the Datastax Cassandra Driver. Cassava provides a higher-level statement execution interface while still supporting asynchronous queries and the ability to connect to multiple clusters.

If prepared incorrectly, the cassava plant can produce cyanide, a deadly compound when consumed.

Installation

Add this line to your application's Gemfile:

gem 'cassava_rb', github: 'backupify/cassava'

And then execute:

$ bundle

Or install it yourself as:

$ gem install cassava_rb

Usage

Creating a client requires a Cassandra::Session object:

require 'cassava'
cluster = Cassandra.cluster
session = cluster.connect('a_keyspace')
client = Cassava::Client.new(session)

Insert

client.insert(:table, :id => 'id', :a => 1, :b => 'b')

Select

A select statement is built and then executed. To create a statement that will select all columns:

statement = client.select(:table)

This statement can then be further refined:

new_statement = statement.where(:id => 'id').limit(2)

and then executed:

result = new_statement.execute

or executed asynchronously:

promise = new_statement.execute_async

To select only certain rows, provide those rows to the select method:

client.select(:table, [:id, :a, :b]).execute

Ordering can be specified using the order method:

client.select(:table).where('id = ? AND a > ?', 1, 'b').order(:a, :desc).execute

Filtering is permitting with the allow_filtering method.

Multiple records can be specified by passing an array of values, but this will generate an CQL IN query and should be used with caution:

client.select(:table).where(:id => 1, :a => [1, 2])

Delete

To delete an entire record:

client.delete(table).where(:id => 1, :a => 1).execute

To delete only certain columns:

client.delete(table, [:c, :d]).where(:id => 1, :a => 1).execute

Note here that :id and :a must be part of the primary key and :c and :d must not be part of the primary key.

Contributing

1. Fork it ( https://github.com/backupify/cassava/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request