dulldb

README

DullDB

The most stupid (that's to say simple) actually useful database.

Features

• K.I.S.S.
• NoSQL (but keep in mind that "schemaless" is a myth!)
• fully ACID
• multiple producer*, multiple consumer and lock-free
• web-scale ;-) (no limits on producers* or consumers amount)
• cross-platform (even a DullDB database by itself)
• open and well-known storage format
• read performance benefits if the OS caches disk data (e.g. Linux)

* if the OS allows to overwrite a file by renaming while it's open and being read (e.g. *nix)

How it works

The complete database is a single JSON file with just the payload. It's written atomically, i.e. by write(2), fsync(2), close(2) and rename(2). This way:

• Changes to the data are atomic due to rename(2).
• The data stays consistent due to fsync(2).
• "Transactions" (that's to say writes) are isolated from each other due to rename(2) (the last rename wins).
• "Commits" (that's to say writes) are durable due to fsync(2).
• Multiple consumers can read(2) the file at the same time, even while multiple producers are performing write(2) or rename(2) without locking anything.

(The features not explained by the bullet points above are implied by the database format itself.)

Drawbacks

The whole database has to be read or written at once.

Usage

go get github.com/Al2Klimov/DullDB/v1

package main

import "github.com/Al2Klimov/DullDB/v1"

func main() {
	err := dulldb.Replace(
		"persons.json",
		[]struct{ Name string }{{"Alice"}, {"Bob"}, {"Carl"}},
	)
	if err != nil {
		panic(err)
	}
}

package main

import (
	"fmt"
	"github.com/Al2Klimov/DullDB/v1"
)

func main() {
	var persons []struct{ Name string }
	if err := dulldb.Select("persons.json", &persons); err != nil {
		panic(err)
	}
	fmt.Print(persons)
}

Result: [{Alice} {Bob} {Carl}]

Documentation

Index

• func Replace(into string, value interface{}) fuel.ErrorWithStack
• func Select(from string, to interface{}) fuel.ErrorWithStack

Functions

func Replace

func Replace(into string, value interface{}) fuel.ErrorWithStack

Replace saves the data $value into the database file $into (as with json.Marshal).

func Select

func Select(from string, to interface{}) fuel.ErrorWithStack

Select loads the database file $from into *$to (as with json.Unmarshal).