Package gocql implements a fast and robust Cassandra client for the Go programming language.
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.github [skip-ci] fix typo Jan 13, 2018
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testdata add benchmark for result parsing Oct 18, 2015
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.travis.yml [skip ci] travis: only build master May 21, 2018
AUTHORS Add frame header observer for per-frame instrumentation Jun 2, 2018
CONTRIBUTING.md update README to match Travis CI Sep 15, 2016
LICENSE Remove references to google in LICENSE Sep 26, 2016
README.md Added go-cql-driver to readme (#1111) May 15, 2018
address_translators.go adding AddressTranslator interface and impl for use in ec2 Nov 3, 2016
address_translators_test.go adding AddressTranslator interface and impl for use in ec2 Nov 3, 2016
batch_test.go TokenAwarePolicy: use token replicas per placement strategy (#1039) Dec 30, 2017
cass1batch_test.go should close the session regardless of failure Feb 4, 2016
cassandra_test.go Fixing expected value for TestRebindQueryInfo when q.Bind(24). (#1075) Mar 19, 2018
cluster.go all: gofmt (#1145) Jun 17, 2018
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conn.go Update keepalive in the dialer (#1150) Jul 31, 2018
conn_test.go fix recordingFrameHeaderObserver race (#1136) Jun 2, 2018
connectionpool.go return deep copy of ssl config (#1143) Jun 17, 2018
control.go conn: store host info on the connection (#1134) Jun 2, 2018
control_test.go Connect to multiple hosts behind a DNS name (#1022) Nov 21, 2017
debug_off.go rename debug -> gocqlDebug Feb 2, 2016
debug_on.go rename debug -> gocqlDebug Feb 2, 2016
doc.go Add vgo support (#1086) Apr 11, 2018
errors.go frame: add writeFailure error Apr 30, 2016
errors_test.go use control connection to create tables in tests Oct 18, 2015
events.go framer: remove framerpool May 22, 2018
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events_test.go typo fix: Debouncer Oct 19, 2016
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filters_test.go Fix more hostinfo (#888) Jun 24, 2017
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helpers.go metadata: fix all types being NativeType (#1052) Jan 23, 2018
helpers_test.go metadata: fix all types being NativeType (#1052) Jan 23, 2018
host_source.go ring describer: fix getHostInfo (#1014) Oct 31, 2017
host_source_gen.go hostinfo: fix using default conn and overriding values (#1009) Oct 28, 2017
host_source_test.go refactor host discovery Oct 18, 2017
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integration.sh tests: enable race detector May 21, 2018
logger.go Added ConnectTimeout for initial connections to nodes Feb 9, 2017
marshal.go marshal: fix marshalling of ints with a wrong type (#1058) Feb 5, 2018
marshal_test.go marshall: handle time encoded values (#960) Aug 12, 2017
metadata.go metadata: skip adding columns to tables which we dont have May 22, 2018
metadata_test.go metadata: dont use strings for column kinds Oct 22, 2016
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prepared_cache.go Revert "Use RWMutex in prepared statement cache" Oct 28, 2016
query_executor.go ObservedQuery,ObservedBatch: replace string address with hostinfo (#1138 Jun 2, 2018
ring.go Acquire exclusive lock when updating (#1025) Nov 28, 2017
ring_test.go Fix more hostinfo (#888) Jun 24, 2017
session.go ObservedQuery,ObservedBatch: replace string address with hostinfo (#1138 Jun 2, 2018
session_connect_test.go session: improve host setup in session Oct 24, 2017
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stress_test.go cluster: remove NumStreams config Nov 21, 2015
token.go TokenAwarePolicy: use token replicas per placement strategy (#1039) Dec 30, 2017
token_test.go TokenAwarePolicy: use token replicas per placement strategy (#1039) Dec 30, 2017
topology.go metadata: remove class from keyspace strategy options. (#1051) Jan 22, 2018
topology_test.go TokenAwarePolicy: use token replicas per placement strategy (#1039) Dec 30, 2017
tuple_test.go marshall: correctly handle null tuple elements (#985) Sep 30, 2017
udt_test.go tests: use session protocol version not the flag (#934) Jul 8, 2017
uuid.go Add TimeUUIDWith function (#1029) Dec 7, 2017
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wiki_test.go gofmt -s Feb 4, 2016

README.md

gocql

Join the chat at https://gitter.im/gocql/gocql Build Status GoDoc

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

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

Supported Versions

The following matrix shows the versions of Go and Cassandra that are tested with the integration test suite as part of the CI build:

Go/Cassandra 2.1.x 2.2.x 3.0.x
1.8 yes yes yes
1.9 yes yes yes

Gocql has been tested in production against many different versions of Cassandra. Due to limits in our CI setup we only test against the latest 3 major releases, which coincide with the official support from the Apache project.

Sunsetting Model

In general, the gocql team will focus on supporting the current and previous versions of Go. gocql may still work with older versions of Go, but official support for these versions will have been sunset.

Installation

go get github.com/gocql/gocql

Features

  • Modern Cassandra client using the native transport
  • Automatic type conversions 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 conversions 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 n concurrent queries (whereby n is the limit set by the protocol version the client chooses to use)
    • Optional automatic discovery of nodes
    • Policy based connection pool with token aware and round-robin policy implementations
  • Support for password authentication
  • Iteration over paged results with configurable page size
  • Support for TLS/SSL
  • Optional frame compression (using snappy)
  • Automatic query preparation
  • Support for query tracing
  • Support for Cassandra 2.1+ binary protocol version 3
    • Support for up to 32768 streams
    • Support for tuple types
    • Support for client side timestamps by default
    • Support for UDTs via a custom marshaller or struct tags
  • Support for Cassandra 3.0+ binary protocol version 4
  • An API to access the schema metadata of a given keyspace

Performance

While the driver strives to be highly performant, there are cases where it is difficult to test and verify. The driver is built with maintainability and code readability in mind first and then performance and features, as such every now and then performance may degrade, if this occurs please report and issue and it will be looked at and remedied. The only time the driver copies data from its read buffer is when it Unmarshal's data into supplied types.

Some tips for getting more performance from the driver:

  • Use the TokenAware policy
  • Use many goroutines when doing inserts, the driver is asynchronous but provides a synchronous API, it can execute many queries concurrently
  • Tune query page size
  • Reading data from the network to unmarshal will incur a large amount of allocations, this can adversely affect the garbage collector, tune GOGC
  • Close iterators after use to recycle byte buffers

Important Default Keyspace Changes

gocql no longer supports executing "use " statements to simplify 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

/* Before you execute the program, Launch `cqlsh` and execute:
create keyspace example with replication = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };
create table example.tweet(timeline text, id UUID, text text, PRIMARY KEY(id));
create index on example.tweet(timeline);
*/
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

	/* Search for a specific set of records whose 'timeline' column matches
	 * the value 'me'. The secondary index that we created earlier will be
	 * used for optimizing the search */
	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)
	}
}

Data Binding

There are various ways to bind application level data structures to CQL statements:

  • You can write the data binding by hand, as outlined in the Tweet example. This provides you with the greatest flexibility, but it does mean that you need to keep your application code in sync with your Cassandra schema.
  • You can dynamically marshal an entire query result into an []map[string]interface{} using the SliceMap() API. This returns a slice of row maps keyed by CQL column names. This method requires no special interaction with the gocql API, but it does require your application to be able to deal with a key value view of your data.
  • As a refinement on the SliceMap() API you can also call MapScan() which returns map[string]interface{} instances in a row by row fashion.
  • The Bind() API provides a client app with a low level mechanism to introspect query meta data and extract appropriate field values from application level data structures.
  • The gocqlx package is an idiomatic extension to gocql that provides usability features. With gocqlx you can bind the query parameters from maps and structs, use named query parameters (:identifier) and scan the query results into structs and slices. It comes with a fluent and flexible CQL query builder that supports full CQL spec, including BATCH statements and custom functions.
  • Building on top of the gocql driver, cqlr adds the ability to auto-bind a CQL iterator to a struct or to bind a struct to an INSERT statement.
  • Another external project that layers on top of gocql is cqlc which generates gocql compliant code from your Cassandra schema so that you can write type safe CQL statements in Go with a natural query syntax.
  • gocassa is an external project that layers on top of gocql to provide convenient query building and data binding.
  • gocqltable provides an ORM-style convenience layer to make CRUD operations with gocql easier.

Ecosystem

The following community maintained tools are known to integrate with gocql:

  • gocqlx is a gocql extension that automates data binding, adds named queries support, provides flexible query builders and plays well with gocql.
  • journey is a migration tool with Cassandra support.
  • negronicql is gocql middleware for Negroni.
  • cqlr adds the ability to auto-bind a CQL iterator to a struct or to bind a struct to an INSERT statement.
  • 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.
  • gocassa provides query building, adds data binding, and provides easy-to-use "recipe" tables for common query use-cases.
  • gocqltable is a wrapper around gocql that aims to simplify common operations.
  • gockle provides simple, mockable interfaces that wrap gocql types
  • scylladb is a fast Apache Cassandra-compatible NoSQL database
  • go-cql-driver is an CQL driver conforming to the built-in database/sql interface. It is good for simple use cases where the database/sql interface is wanted. The CQL driver is a wrapper around this project.

Other Projects

  • 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.

SEO

For some reason, when you Google golang cassandra, this project doesn't feature very highly in the result list. But if you Google go cassandra, then we're a bit higher up the list. So this is note to try to convince Google that golang is an alias for Go.

License

Copyright (c) 2012-2016 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.