erobit / elixir-cassandra

An Elixir client for Apache Cassandra.

Cassandra

An Elixir driver for Apache Cassandra.

This driver works with Cassandra Query Language version 3 (CQL3) and Cassandra's native protocol v4.

Features

• Automatic peer discovery
• Configurable load-balancing/retry/reconnection policies
• Ecto like Repo supervisor
• Asynchronous execution through Tasks
• Prepared statements with named and position based values
• Batch statement

Todo

• Token based load-balancing policy
• Compression
• Authentication and SSL encryption
• User Defined Types
• Use prepared result_metadata optimization

Installation

Add cassandra to your list of dependencies in mix.exs:

def deps do
  [{:cassandra, "~> 1.0.0-beta.1"}]
end

Quick Start

defmodule Repo do
  use Cassandra
end

{:ok, _} = Repo.start_link
# uses "127.0.0.1:9042" as contact point by default
# discovers other nodes on first connection

{:ok, _} = Repo.execute """
  CREATE KEYSPACE IF NOT EXISTS test
    WITH replication = {'class':'SimpleStrategy','replication_factor':1};
  """, consistency: :all

{:ok, _} = Repo.execute """
  CREATE TABLE IF NOT EXISTS test.users (
    id timeuuid,
    name varchar,
    age int,
    PRIMARY KEY (id)
  );
  """, consistency: :all

{:ok, insert} = Repo.prepare """
  INSERT INTO test.users (id, name, age) VALUES (now(), ?, ?);
  """

users = [
  %{name: "Bilbo", age: 50},
  %{name: "Frodo", age: 33},
  %{name: "Gandolf", age: 2019},
]

users
|> Enum.map(&Task.async(fn -> Repo.execute(insert, values: &1, consistency: :all) end))
|> Enum.map(&Task.await/1)
|> Enum.each(&IO.inspect(&1))

{:ok, rows} = Repo.execute("SELECT * FROM test.users;", consistency: :all)

# {:ok,
#  %CQL.Result.Rows{
#   columns: ["id", "age", "name"],
#   rows_count: 3,
#   rows: [
#    ["831e5df2-a0e1-11e6-b9af-6d2c86545d91", 2019, "Gandolf"],
#    ["831e5df1-a0e1-11e6-b9af-6d2c86545d91", 33, "Frodo"],
#    ["831e5df0-a0e1-11e6-b9af-6d2c86545d91", 50, "Bilbo"]
#   ]
# }}