Genji

Document-oriented, embedded, SQL database

Table of contents
Introduction
Features
Installation
Usage
- Using Genji's API
- Using database/sql
Engines
Genji shell
Contributing

Introduction

Genji is a schemaless database that allows running SQL queries on documents.

Checkout the SQL documentation, the Go doc and the usage example in the README to get started quickly.

⚠️ Genji's API is still unstable: Database compatibility is not guaranteed before reaching v1.0.0

Features

Optional schemas: Genji tables are schemaless, but it is possible to add constraints on any field to ensure the coherence of data within a table.
Multiple Storage Engines: It is possible to store data on disk or in ram, but also to choose between B-Trees and LSM trees. Genji relies on BoltDB and Badger to manage data.
Transaction support: Read-only and read/write transactions are supported by default.
SQL and Documents: Genji mixes the best of both worlds by combining powerful SQL commands with JSON.
Easy to use, easy to learn: Genji was designed for simplicity in mind. It is really easy to insert and read documents of any shape.
Compatible with the database/sql package

Installation

Install the Genji database

go get github.com/genjidb/genji

Usage

There are two ways of using Genji, either by using Genji's API or by using the database/sql package.

Using Genji's API

package main

import (
	"fmt"
	"log"

	"github.com/genjidb/genji"
	"github.com/genjidb/genji/document"
)

func main() {
    // Create a database instance, here we'll store everything on-disk using the BoltDB engine
    db, err := genji.Open("my.db")
    if err != nil {
        log.Fatal(err)
    }
    // Don't forget to close the database when you're done
    defer db.Close()

    ctx := context.Background()

    // Create a table. Schemas are optional, you don't need to specify one if not needed
    err = db.Exec(ctx, "CREATE TABLE user")

    // Create an index
    err = db.Exec(ctx, "CREATE INDEX idx_user_name ON test (name)")

    // Insert some data
    err = db.Exec(ctx, "INSERT INTO user (id, name, age) VALUES (?, ?, ?)", 10, "Foo1", 15)

    // Supported values can go from simple integers to richer data types like lists or documents
    err = db.Exec(ctx, `
    INSERT INTO user (id, name, age, address, friends)
    VALUES (
        11,
        'Foo2',
        20,
        {"city": "Lyon", "zipcode": "69001"},
        ["foo", "bar", "baz"]
    )`)

    // Go structures can be passed directly
    type User struct {
        ID              uint
        Name            string
        TheAgeOfTheUser float64 `genji:"age"`
        Address         struct {
            City    string
            ZipCode string
        }
    }

    // Let's create a user
    u := User{
        ID:              20,
        Name:            "foo",
        TheAgeOfTheUser: 40,
    }
    u.Address.City = "Lyon"
    u.Address.ZipCode = "69001"

    err = db.Exec(ctx, `INSERT INTO user VALUES ?`, &u)

    // Query some documents
    res, err := db.Query(ctx, "SELECT id, name, age, address FROM user WHERE age >= ?", 18)
    // always close the result when you're done with it
    defer res.Close()

    // Iterate over the results
    err = res.Iterate(func(d document.Document) error {
        // When querying an explicit list of fields, you can use the Scan function to scan them
        // in order. Note that the types don't have to match exactly the types stored in the table
        // as long as they are compatible.
        var id int
        var name string
        var age int32
        var address struct {
            City    string
            ZipCode string
        }

        err = document.Scan(d, &id, &name, &age, &address)
        if err != nil {
            return err
        }

        fmt.Println(id, name, age, address)

        // It is also possible to scan the results into a structure
        var u User
        err = document.StructScan(d, &u)
        if err != nil {
            return err
        }

        fmt.Println(u)

        // Or scan into a map
        var m map[string]interface{}
        err = document.MapScan(d, &m)
        if err != nil {
            return err
        }

        fmt.Println(m)
        return nil
    })
}

Using database/sql

// import Genji as a blank import
import _ "github.com/genjidb/genji/sql/driver"

// Create a sql/database DB instance
db, err := sql.Open("genji", "my.db")
if err != nil {
    log.Fatal(err)
}
defer db.Close()

// Then use db as usual
res, err := db.ExecContext(...)
res, err := db.Query(...)
res, err := db.QueryRow(...)

Engines

Genji currently supports storing data in BoltDB, Badger and in-memory.

Using the BoltDB engine

import (
    "log"

    "github.com/genjidb/genji"
)

func main() {
    db, err := genji.Open("my.db")
    defer db.Close()
}

Using the memory engine

import (
    "log"

    "github.com/genjidb/genji"
)

func main() {
    db, err := genji.Open(":memory:")
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()
}

Using the Badger engine

First install the module

go get github.com/genjidb/genji/engine/badgerengine

import (
    "log"

    "github.com/genjidb/genji"
    "github.com/genjidb/genji/engine/badgerengine"
    "github.com/dgraph-io/badger/v2"
)

func main() {
    // Create a badger engine
    ng, err := badgerengine.NewEngine(badger.DefaultOptions("mydb"))
    if err != nil {
        log.Fatal(err)
    }

    // Pass it to genji
    db, err := genji.New(ng)
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()
}

Genji shell

The genji command line provides an SQL shell that can be used to create, modify and consult Genji databases.

Make sure the Genji command line is installed:

go get github.com/genjidb/genji/cmd/genji

Example:

# Opening an in-memory database:
genji

# Opening a BoltDB database:
genji my.db

# Opening a Badger database:
genji --badger pathToData

Contributing

Contributions are welcome!

Feedback
Feature ideas
Bug reports
Pull Requests
Anything that comes to mind to improve Genji!

If you have any doubt, join the Gophers Slack channel or open an issue.

ab22 / genji