gocql

Package Status: Alpha

Package gocql implements a fast and robust Cassandra client for the Go programming language.

Project Website: http://gocql.github.io/
API documentation: http://godoc.org/github.com/gocql/gocql
Discussions: https://groups.google.com/forum/#!forum/gocql

Installation

go get github.com/gocql/gocql

Features

• Modern Cassandra client for Cassandra 1.2 and 2.0
• Automatic type conversations between Cassandra and Go
  • Support for all common types including sets, lists and maps
  • Custom types can implement a Marshaler and Unmarshaler interface
  • Strict type conversations without any loss of precision
  • Built-In support for UUIDs (version 1 and 4)
• Support for logged, unlogged and counter batches
• Cluster management
  • Automatic reconnect on connection failures with exponential falloff
  • Round robin distribution of queries to different hosts
  • Round robin distribution of queries to different connections on a host
  • Each connection can execute up to 128 concurrent queries
  • Optional automatic discovery of nodes
• Iteration over paged results with configurable page size
• Optional frame compression (using snappy)
• Automatic query preparation
• Support for query tracing

Please visit the Roadmap page to see what is on the horizion.

Important Default Keyspace Changes

gocql no longer supports executing "use " statements to simplfy the library. The user still has the ability to define the default keyspace for connections but now the keyspace can only be defined before a session is created. Queries can still access keyspaces by indicating the keyspace in the query:

SELECT * FROM example2.table;

Example of correct usage:

	cluster := gocql.NewCluster("192.168.1.1", "192.168.1.2", "192.168.1.3")
	cluster.Keyspace = "example"
	...
	session, err := cluster.CreateSession()

Example of incorrect usage:

	cluster := gocql.NewCluster("192.168.1.1", "192.168.1.2", "192.168.1.3")
	cluster.Keyspace = "example"
	...
	session, err := cluster.CreateSession()

	if err = session.Query("use example2").Exec(); err != nil {
		log.Fatal(err)
	}

This will result in an err being returned from the session.Query line as the user is trying to execute a "use" statement.

Example

package main

import (
	"fmt"
	"log"

	"github.com/gocql/gocql"
)

func main() {
	// connect to the cluster
	cluster := gocql.NewCluster("192.168.1.1", "192.168.1.2", "192.168.1.3")
	cluster.Keyspace = "example"
	cluster.Consistency = gocql.Quorum
	session, _ := cluster.CreateSession()
	defer session.Close()

	// insert a tweet
	if err := session.Query(`INSERT INTO tweet (timeline, id, text) VALUES (?, ?, ?)`,
		"me", gocql.TimeUUID(), "hello world").Exec(); err != nil {
		log.Fatal(err)
	}

	var id gocql.UUID
	var text string

	// select a single tweet
	if err := session.Query(`SELECT id, text FROM tweet WHERE timeline = ? LIMIT 1`,
		"me").Consistency(gocql.One).Scan(&id, &text); err != nil {
		log.Fatal(err)
	}
	fmt.Println("Tweet:", id, text)

	// list all tweets
	iter := session.Query(`SELECT id, text FROM tweet WHERE timeline = ?`, "me").Iter()
	for iter.Scan(&id, &text) {
		fmt.Println("Tweet:", id, text)
	}
	if err := iter.Close(); err != nil {
		log.Fatal(err)
	}
}

Other Projects

• cqlc generates gocql compliant code from your Cassandra schema so that you can write type safe CQL statements in Go with a natural query syntax.
• gocqldriver is the predecessor of gocql based on Go's "database/sql" package. This project isn't maintained anymore, because Cassandra wasn't a good fit for the traditional "database/sql" API. Use this package instead.

License

Copyright (c) 2012-2014 The gocql Authors. All rights reserved. Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.