dirdb

DirDB - lightning fast database

DirDB key-value directory database

$ npm install dirdb

Run tests

Browse module (e.g. node_modules/dirdb) install directory, and run tests:

$ npm test
# or
$ node test.js

Compare test results with travis run tests.

Include in your script

const dirdb = require('dirdb');

Define the database root directory

First time, make sure the directory exists, is empty, and have the right user permissions mode.

const db = new dirdb('/dir/path/name');

Chain calls

All async method functions returns the object they belong (db core, or db.client() stream).

obj. // < can be: db or db.client() stream
methodAsync(..., (...) => { ... }). // and so on...
methodAsync(..., (...) => { ... });
// ASYNC call example
db. // < can be: db or db.client() stream, see below
put(dirname, key, value1, e => {}). // and so on...
add(dirname, key, value2, e => {});

isdir(dirname)

If dirname exist, return/callback object dirconfig, or undefined if not.

• dirname - String directory table name (folder), without slashes, e.g. name

// SYNC
const dirconfig = db.isdir(dirname);
// ASYNC
db.isdir(dirname, dirconfig => { });

mkdir(dirname[, options])

Make a directory by name, not path, e.g. name. If dirname exist, throw/callback error. Return/callback name on success. For more options, see below.

// SYNC
const name = db.mkdir(dirname);
// ASYNC
db.mkdir(dirname, (error, name) => {
    if (error) { throw error; }
});

rmdir(dirname)

Remove dir name and its contents, throw/callback error if dirname not exists.

// SYNC
db.rmdir(dirname);
// ASYNC
db.rmdir(dirname, error => {
    if (error) { throw error; }
});

list()

Return/callback dbconfig object { dirname: dirconfig, ... }.

// SYNC
const dbconfig = db.list();
// ASYNC
db.list(dbconfig => { });

put(dirname, key, value[, callback])

Throw/callback error if key exists. Return/callback { uid, hash, path } if success.

• dirname - String directory table name, without slashes
• key - String|Buffer
• value - String|Buffer

Return { uid, hash, path }

• uid - String unique id ( birthDateInt36.Index )
• hash - String key hash ( using: dirconfig algorithm + digest )
• path - String path key ( file path.k ) and value ( file path.v )

// SYNC
const { uid, hash, path } = db.put(dirname, key, value);
// ASYNC
db.put(dirname, key, value, (error, uid, hash, path) => {
    if (error) { throw error; }
});

set(dirname, key, value[, callback])

Overwrite value if key exists, or create, if not. Return/callback { uid, hash, path } if success.

// SYNC
const { uid, hash, path } = db.set(dirname, key, value);
// ASYNC
db.set(dirname, key, value, (error, uid, hash, path) => {
    if (error) { throw error; }
});

add(dirname, key, value[, callback])

Append value if key exists, or create, if not. Return/callback { uid, hash, path } if success.

// SYNC
const { uid, hash, path } = db.add(dirname, key, value);
// ASYNC
db.add(dirname, key, value, (error, uid, hash, path) => {
    if (error) { throw error; }
});

get(dirname, key[, callback])

Read key value. Throw/callback error if key not exists. Return/callback { value, uid, hash, path } if success.

// SYNC
const { value, uid, hash, path } = db.get(dirname, key); // value is Buffer
// ASYNC
db.get(dirname, key, (error, value, uid, hash, path) => { // value is Buffer or undefined if error
    if (error) { throw error; }
});

del(dirname, key[, callback])

Delete key. Throw/callback error if key not exists. Return/callback uid if success.

// SYNC
const uid = db.del(dirname, key);
// ASYNC
db.del(dirname, key, (error, uid) => { // uid is String or undefined if error
    if (error) { throw error; }
});

keys(dirname[, range[, callback]])

Return/callback object keylist if success.

• range - Object { start: Number, end: Number }
• keylist - Object { uid: keyhash, ... }

// SYNC
const keylistA = db.keys(dirname); // without range select, return all
const keylistB = db.keys(dirname, { start: 1 }); // without end point, return all except first key ( index: 1, 2, ... )
const keylistC = db.keys(dirname, { start: 0, end: 2 }); // return first two keys ( index: 0 and 1 )
// ASYNC
db.keys(dirname, (error, keylist) => { // without range select, return all
    if (error) { throw error; }
});
// without start point, return first two keys ( index: 0 and 1 )
db.keys(dirname, { end: 2 }, (error, keylist) => { // keylist is Object or undefined if error
    if (error) { throw error; }
});

val(dirname, uid, keyhash[, callback])

Throw/callback error if key not exists. Return/callback { key, value, path } if success. See the above keylist object for uid and keyhash.

// SYNC
const { key, value, path } = db.val(dirname, uid, keyhash); // key and value is Buffer
// ASYNC
db.val(dirname, uid, keyhash, (error, key, value, path) => { // key and value is Buffer or undefined if error
    if (error) { throw error; }
});

stats()

Throw/callback error if key not exists. Return/callback { uid, hash, path, stats } if success.

• stats - Object, key value file lstat fs.Stats

// SYNC
const { uid, hash, path, stats } = db.stats(dirname, key);
// ASYNC
db.stats(dirname, key, (error, uid, hash, path, stats) => {
    if (error) { throw error; }
    // fs.Stats file: path + '.v'
    // require('fs').lstat(path + '.v', (error, stats) => {})
    console.log('Birth time', stats.birthtime);
    console.log('Modified time', stats.mtime);
    console.log('Key value size', stats.size);
});

setgc(dirname, option)

Set dirname GC boolean option. When delete a key using del() function, if GC is enabled (true), the directory where the key-value was saved, is deleted if is empty. Throw/callback error if dirname not exists. Return/callback dirconfig if success.

// SYNC
const dirconfig = db.setgc(dirname, true);
// ASYNC
db.setgc(dirname, false, (error, dirconfig) => { // dirconfig is Object or undefined if error
    if (error) { throw error; }
    console.log('gc', dirconfig.gc);
});

server()

Server stream object. See the stream / socket examples below, of how to pipe server stream into client stream.

client([sync])

Client stream object. Server call method functions is sync false (by default), for sync set true. The sync/async server method can be set individually on any client function, with the last argument.

// call SYNC method functions on server
const clientS = db.client(true);
// call ASYNC method functions on server
const clientA = db.client(); // or false

const client = db.client();
client.set(dirname, key, value, (error, uid) => {
    if (error) { throw error; }
}, true); // true: call SYNC method function on server
client.del(dirname, key, (error, uid) => {
    if (error) { throw error; }
}, false); // false: call ASYNC method function on server

Stream example

const client = db.client();
client.pipe(db.server()).pipe(client);
client.put(dirname, key, value, (error, uid) => {
    if (error) { throw error; }
});

Socket stream example

const net = require('net');
net.createServer(socket => socket.pipe(db.server()).pipe(socket)).
listen(function() { // socket server listen to a random port and address
    const a = this.address(); // get the socket server port and address
    net.connect(a.port, a.address, function() {
        const client = db.client(); // default ASYNC methods on DB core
        this.pipe(client).pipe(this);
        client.set(dirname, key, value, (error, uid) => {
            if (error) { throw error; }
        });
    });
});

mkdir(dirname[, options])

• dirname - String directory table name, without slashes
• options - Object, see below

Directory table options

• level - Number, key hash directory divisor, default 3, minim 0 and max limited by algorithm and digest value, see below
• dmode - Number, directory mode, default 0o700
• fmode - Number, file mode, default 0o600
• algorithm - String, key hash algorithm, default md5, possible: md5 | sha1 | sha256 | sha512
• digest - String, key hash digest, default base64, possible: base64 | hex
• compress - String, zlib compress type, default none, possible: none | deflate | gzip
• gc - Boolean, run garbage collector after key delete, default true

You can overwrite the default directory options:

const db = new dirdb('/dir/pathname', {
    // overwrite default options
    level: 3,
    digest: 'hex',
    gc: false
});

mkdir() options example

High level, means high directory divisor. To increase I/O speed on high number of keys entries, make sure a high level value is defined on db.mkdir options. If there is only few key entries on directory, high level value will decrease the I/O speed.

// dir name 'logs'
db.mkdir('logs', {
    level: 4,
    algorithm: 'sha1',
    digest: 'hex',
    // WARNING: when use db.add() "append" on compress other than 'none'
    // make sure, the key value will not be corrupted if append function will be used
    compress: 'gzip'
});
// sha1 = 35 unique characters , level = 4
console.log('divisor', Math.pow(35, 4)); // 1500625
// key entries are stored on 1500625 max sub-directories

Few examples of how to calculate the directory divisor, at maximum level

• md5-base64 Math.pow(64, 22) - 64 unique characters, 22 long max level
• md5-hex Math.pow(35, 32) - 35 unique characters, 32 long max level
• sha1-base64 Math.pow(64, 27) - 64 unique characters, 27 long max level
• sha1-hex Math.pow(35, 40) - 35 unique characters, 40 long max level

High Availability, Backup and Restore Operations

DirDB is very light and simple database, because of that, HA / Back-Up / Restore can be done with tools like rsync or unison.

# Backup example
$ rsync -abqz dirA dirB
# High Availability example
$ unison -auto dirA/ dirB/

• dirA local directory ( primary )
• dirB remote / network directory ( secondary )

// High Availability, using unison
const dbA = new dirdb(dirA); // primary DB
// Host A ( local )
net.createServer(socket => socket.pipe(dbA.server()).pipe(socket));
// dirB > ssh://dev@192.168.1.10/home/alice/dirB
// OR
// dirB > socket://remote_host:port_num/path/to/dirB
const dbB = new dirdb(dirB); // secondary DB
// Host B ( remote ) - another node.js server
net.createServer(socket => socket.pipe(dbB.server()).pipe(socket));

DB core only (not client), async stream write/read big values

const fs = require('fs');
// db core, write big value, source file '/path/big/file.ext'
db.put(dirname, key, '', (error, uid, hash, path) => { // or db.set() to overwrite, if key exists
    if (error) { throw error; }
    fs.createReadStream('/path/big/file.ext').pipe(fs.createWriteStream(path + '.v'));
});
// db core, append big value, source file '/path/big/file.ext'
db.add(dirname, key, '', (error, uid, hash, path) => {
    if (error) { throw error; }
    fs.createReadStream('/path/big/file.ext').pipe(fs.createWriteStream(path + '.v', { flags: 'a' }));
});
// db core, read big value
db.stats(dirname, key, (error, uid, hash, path, stats) => {
    if (error) { throw error; }
    fs.createReadStream(path + '.v').on('data', data => {});
});

For more info, consult or run the test.js file.

DirDB is licensed under the MIT license. See the included LICENSE file for more details.