genji

README

Genji

Document-oriented, embedded, SQL database

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/tie/genji-release-test

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 (
    "context"
    "fmt"
    "log"

    "github.com/tie/genji-release-test"
    "github.com/tie/genji-release-test/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()

    // Attach context, e.g. (*http.Request).Context().
    db = db.WithContext(context.Background())

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

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

    // Insert some data
    err = db.Exec("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(`
    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(`INSERT INTO user VALUES ?`, &u)

    // Query some documents
    res, err := db.Query("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/tie/genji-release-test/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/tie/genji-release-test"
)

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

Using the memory engine

import (
    "log"

    "github.com/tie/genji-release-test"
)

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/tie/genji-release-test/engine/badgerengine

import (
    "context"
    "log"

    "github.com/tie/genji-release-test"
    "github.com/tie/genji-release-test/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(context.Background(), 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/tie/genji-release-test/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!

See ARCHITECTURE.md and CONTRIBUTING.md.

Thank you, contributors!

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

Documentation

Overview

Package genji implements a document-oriented, embedded SQL database. Genji supports various engines that write data on-disk, like BoltDB or Badger, and in memory.

Example

package main

import (
	"fmt"

	"github.com/tie/genji-release-test"
	"github.com/tie/genji-release-test/document"
)

type User struct {
	ID      int64
	Name    string
	Age     uint32
	Address struct {
		City    string
		ZipCode string
	}
}

func main() {
	// Create a database instance, here we'll store everything in memory
	db, err := genji.Open(":memory:")
	if err != nil {
		panic(err)
	}
	defer db.Close()

	// Create a table. Genji tables are schemaless by default, you don't need to specify a schema.
	err = db.Exec("CREATE TABLE user")
	if err != nil {
		panic(err)
	}

	// Create an index.
	err = db.Exec("CREATE INDEX idx_user_name ON user (name)")
	if err != nil {
		panic(err)
	}

	// Insert some data
	err = db.Exec("INSERT INTO user (id, name, age) VALUES (?, ?, ?)", 10, "foo", 15)
	if err != nil {
		panic(err)
	}

	// Insert some data using document notation
	err = db.Exec(`INSERT INTO user VALUES {id: 12, "name": "bar", age: ?, address: {city: "Lyon", zipcode: "69001"}}`, 16)
	if err != nil {
		panic(err)
	}

	// Structs can be used to describe a document
	err = db.Exec("INSERT INTO user VALUES ?, ?", &User{ID: 1, Name: "baz", Age: 100}, &User{ID: 2, Name: "bat"})
	if err != nil {
		panic(err)
	}

	// Query some documents
	stream, err := db.Query("SELECT * FROM user WHERE id > ?", 1)
	if err != nil {
		panic(err)
	}
	// always close the result when you're done with it
	defer stream.Close()

	// Iterate over the results
	err = stream.Iterate(func(d document.Document) error {
		var u User

		err = document.StructScan(d, &u)
		if err != nil {
			return err
		}

		fmt.Println(u)
		return nil
	})
	if err != nil {
		panic(err)
	}

}

Output:

{10 foo 15 { }}
{12 bar 16 {Lyon 69001}}
{2 bat 0 { }}

Index

• type DB
  • func New(ctx context.Context, ng engine.Engine) (*DB, error)
  • func Open(path string) (*DB, error)
  • func (db *DB) Begin(writable bool) (*Tx, error)
  • func (db *DB) Close() error
  • func (db *DB) Exec(q string, args ...interface{}) error
  • func (db *DB) Query(q string, args ...interface{}) (*query.Result, error)
  • func (db *DB) QueryDocument(q string, args ...interface{}) (document.Document, error)
  • func (db *DB) Update(fn func(tx *Tx) error) error
  • func (db *DB) View(fn func(tx *Tx) error) error
  • func (db *DB) WithContext(ctx context.Context) *DB
• type Tx
  • func (tx *Tx) Exec(q string, args ...interface{}) (err error)
  • func (tx *Tx) Query(q string, args ...interface{}) (*query.Result, error)
  • func (tx *Tx) QueryDocument(q string, args ...interface{}) (document.Document, error)

Examples

• Package
• Tx

Types

type DB

type DB struct {
	DB *database.Database
	// contains filtered or unexported fields
}

DB represents a collection of tables stored in the underlying engine.

func New

func New(ctx context.Context, ng engine.Engine) (*DB, error)

New initializes the DB using the given engine.

func Open

func Open(path string) (*DB, error)

Open creates a Genji database at the given path. If path is equal to ":memory:" it will open an in-memory database, otherwise it will create an on-disk database using the BoltDB engine.

func (*DB) Begin

func (db *DB) Begin(writable bool) (*Tx, error)

Begin starts a new transaction. The returned transaction must be closed either by calling Rollback or Commit.

func (*DB) Close

func (db *DB) Close() error

Close the database.

func (*DB) Exec

func (db *DB) Exec(q string, args ...interface{}) error

Exec a query against the database without returning the result.

func (*DB) Query

func (db *DB) Query(q string, args ...interface{}) (*query.Result, error)

Query the database and return the result. The returned result must always be closed after usage.

func (*DB) QueryDocument

func (db *DB) QueryDocument(q string, args ...interface{}) (document.Document, error)

QueryDocument runs the query and returns the first document. If the query returns no error, QueryDocument returns database.ErrDocumentNotFound.

func (*DB) Update

func (db *DB) Update(fn func(tx *Tx) error) error

Update starts a read-write transaction, runs fn and automatically commits it.

func (*DB) View

func (db *DB) View(fn func(tx *Tx) error) error

View starts a read only transaction, runs fn and automatically rolls it back.

func (*DB) WithContext

func (db *DB) WithContext(ctx context.Context) *DB

WithContext creates a new database handle using the given context for every operation.

type Tx

type Tx struct {
	*database.Transaction
}

Tx represents a database transaction. It provides methods for managing the collection of tables and the transaction itself. Tx is either read-only or read/write. Read-only can be used to read tables and read/write can be used to read, create, delete and modify tables.

Example

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

tx, err := db.Begin(true)
if err != nil {
	panic(err)
}
defer tx.Rollback()

err = tx.Exec("CREATE TABLE IF NOT EXISTS user")
if err != nil {
	log.Fatal(err)
}

err = tx.Exec("INSERT INTO user (id, name, age) VALUES (?, ?, ?)", 10, "foo", 15)
if err != nil {
	log.Fatal(err)
}

d, err := tx.QueryDocument("SELECT id, name, age FROM user WHERE name = ?", "foo")
if err != nil {
	panic(err)
}

var u User
err = document.StructScan(d, &u)
if err != nil {
	panic(err)
}

fmt.Println(u)

var id uint64
var name string
var age uint8

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

fmt.Println(id, name, age)

err = tx.Commit()
if err != nil {
	panic(err)
}

Output:

{10 foo 15 { }}
10 foo 15

func (*Tx) Exec

func (tx *Tx) Exec(q string, args ...interface{}) (err error)

Exec a query against the database within tx and without returning the result.

func (*Tx) Query

func (tx *Tx) Query(q string, args ...interface{}) (*query.Result, error)

Query the database withing the transaction and returns the result. Closing the returned result after usage is not mandatory.

func (*Tx) QueryDocument

func (tx *Tx) QueryDocument(q string, args ...interface{}) (document.Document, error)

QueryDocument runs the query and returns the first document. If the query returns no error, QueryDocument returns database.ErrDocumentNotFound.