scylladb/gocqlx

🚀 GocqlX

GocqlX makes working with Scylla easy and less error-prone. It’s inspired by Sqlx, a tool for working with SQL databases, but it goes beyond what Sqlx provides.

Compatibility

Versions of GocqlX prior to v3.0.0 are compatible with both Apache Cassandra’s gocql and ScyllaDB’s fork. However, starting with v3.0.0, GocqlX exclusively supports the scylladb/gocql driver. If you are using GocqlX v3.0.0 or newer, you must ensure your go.mod includes a replace directive to point to ScyllaDB’s fork:

// Use the latest version of scylladb/gocql; check for updates at https://github.com/scylladb/gocql/releases
replace github.com/gocql/gocql => github.com/scylladb/gocql v1.16.0

This is required because GocqlX relies on ScyllaDB-specific extensions and bug fixes introduced in the gocql fork. Attempting to use the standard gocql driver with GocqlX v3.0.0+ may lead to build or runtime issues.

Features

• Binding query parameters from struct fields, map, or both
• Scanning query results into structs based on field names
• Convenient functions for common tasks such as loading a single row into a struct or all rows into a slice (list) of structs
• Making any struct a UDT without implementing marshalling functions
• GocqlX is fast. Its performance is comparable to raw driver. You can find some benchmarks here.

Subpackages provide additional functionality:

• CQL query builder (package qb)
• CRUD operations based on table model (package table)
• Database migrations (package migrate)

Installation GocqlX

Add GocqlX to your Go module:

go get github.com/scylladb/gocqlx/v3

Installation schemagen

Unfortunately you can't install it via go install, since go.mod contains replace directive. So, you have to check it out and install manually:

git clone [email protected]:scylladb/gocqlx.git
cd gocqlx/cmd/schemagen/
go install .

Getting started

First, import the required packages:

import (
	"fmt"
	"log"

	"github.com/gocql/gocql"
	"github.com/scylladb/gocqlx/v3"
	"github.com/scylladb/gocqlx/v3/qb"
	"github.com/scylladb/gocqlx/v3/table"
)

Wrap gocql Session:

// Create gocql cluster.
cluster := gocql.NewCluster(hosts...)
// Wrap session on creation, gocqlx session embeds gocql.Session pointer.
session, err := gocqlx.WrapSession(cluster.CreateSession())
if err != nil {
	log.Fatal(err)
}
defer session.Close()

Specify table model:

// metadata specifies table name and columns it must be in sync with schema.
var personMetadata = table.Metadata{
	Name:    "person",
	Columns: []string{"first_name", "last_name", "email"},
	PartKey: []string{"first_name"},
	SortKey: []string{"last_name"},
}

// personTable allows for simple CRUD operations based on personMetadata.
var personTable = table.New(personMetadata)

// Person represents a row in person table.
// Field names are converted to snake case by default, no need to add special tags.
// A field will not be persisted by adding the `db:"-"` tag or making it unexported.
type Person struct {
	FirstName string
	LastName  string
	Email     []string
	HairColor string `db:"-"`  // exported and skipped
	eyeColor  string           // unexported also skipped
}

Bind data from a struct and insert a row:

p := Person{
	"Michał",
	"Matczuk",
	[]string{"[email protected]"},
	"red",    // not persisted
	"hazel"   // not persisted
}
q := session.Query(personTable.Insert()).BindStruct(p)
if err := q.ExecRelease(); err != nil {
	log.Fatal(err)
}

Load a single row to a struct:

p := Person{
	"Michał",
	"Matczuk",
	nil, // no email
}
q := session.Query(personTable.Get()).BindStruct(p)
if err := q.GetRelease(&p); err != nil {
	log.Fatal(err)
}
fmt.Println(p)
// stdout: {Michał Matczuk [[email protected]]}

Load all rows in to a slice:

var people []Person
q := session.Query(personTable.Select()).BindMap(qb.M{"first_name": "Michał"})
if err := q.SelectRelease(&people); err != nil {
	log.Fatal(err)
}
fmt.Println(people)
// stdout: [{Michał Matczuk [[email protected]]}]

Generating table metadata with schemagen

Installation

go get -u "github.com/scylladb/gocqlx/v3/cmd/schemagen"

Usage:

schemagen [flags]

Flags:
  -cluster string
    	a comma-separated list of host:port tuples (default "127.0.0.1")
  -keyspace string
    	keyspace to inspect (required)
  -output string
    	the name of the folder to output to (default "models")
  -pkgname string
    	the name you wish to assign to your generated package (default "models") 

Example:

Running the following command for examples keyspace:

schemagen -cluster="127.0.0.1:9042" -keyspace="examples" -output="models" -pkgname="models"

Generates models/models.go as follows:

// Code generated by "gocqlx/cmd/schemagen"; DO NOT EDIT.

package models

import "github.com/scylladb/gocqlx/v3/table"

// Table models.
var (
	Playlists = table.New(table.Metadata{
		Name: "playlists",
		Columns: []string{
			"album",
			"artist",
			"id",
			"song_id",
			"title",
		},
		PartKey: []string{
			"id",
		},
		SortKey: []string{
			"title",
			"album",
			"artist",
		},
	})

	Songs = table.New(table.Metadata{
		Name: "songs",
		Columns: []string{
			"album",
			"artist",
			"data",
			"id",
			"tags",
			"title",
		},
		PartKey: []string{
			"id",
		},
		SortKey: []string{},
	})
)

Examples

You can find lots of examples in example_test.go.

Go and run them locally:

make run-scylla
make run-examples

Training

The course Using Scylla Drivers in Scylla University explains how to use drivers in different languages to interact with a Scylla cluster. The lesson, Golang and Scylla Part 3 - GoCQLX, goes over a sample application that, using GoCQLX, interacts with a three-node Scylla cluster. It connects to a Scylla cluster, displays the contents of a table, inserts and deletes data, and shows the contents of the table after each action. Scylla University includes other training material and online courses which will help you become a Scylla NoSQL database expert.

Performance

GocqlX performance is comparable to the raw gocql driver. Below benchmark results running on my laptop.

BenchmarkBaseGocqlInsert            2392            427491 ns/op            7804 B/op         39 allocs/op
BenchmarkGocqlxInsert               2479            435995 ns/op            7803 B/op         39 allocs/op
BenchmarkBaseGocqlGet               2853            452384 ns/op            7309 B/op         35 allocs/op
BenchmarkGocqlxGet                  2706            442645 ns/op            7646 B/op         38 allocs/op
BenchmarkBaseGocqlSelect             747           1664365 ns/op           49415 B/op        927 allocs/op
BenchmarkGocqlxSelect                667           1877859 ns/op           42521 B/op        932 allocs/op

See the benchmark in benchmark_test.go.

License

Copyright (C) 2017 ScyllaDB

This project is distributed under the Apache 2.0 license. See the LICENSE file for details. It contains software from:

• gocql project, licensed under the BSD license
• sqlx project, licensed under the MIT license

Apache®, Apache Cassandra® are either registered trademarks or trademarks of the Apache Software Foundation in the United States and/or other countries. No endorsement by The Apache Software Foundation is implied by the use of these marks.

GitHub star is always appreciated!