Fast & simple storage - a Dart LevelDB wrapper

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Introduction

LevelDB is a simple key/value data store built by Google, inspired by BigTable. It's used in Google Chrome and many other products. LevelDB supports arbitrary byte arrays as both keys and values, singular get, put and delete operations, batched put and delete, bi-directional iterators and simple compression using the very fast Snappy algorithm.

leveldb_dart aims to expose the features of LevelDB in a Dart-friendly way.

LevelDB stores entries sorted lexicographically by keys. This makes LevelDB.getItems a very powerful query mechanism.

Platform Support

Modern 64-bit Linux platforms should work fine. The following distributions are known to work:

  • x Fedora 26 64-bit
  • x Fedora 25 64-bit
  • x Ubuntu 14.04 64-bit
  • x Ubuntu 15.10 64-bit

Unsupported platforms:

Basic usage

Add leveldb to your pubspec.yaml file.

name: myproject
dependencies:
  leveldb:

Open a database and read/write some keys and values..

import 'dart:async';
import 'package:leveldb/leveldb.dart';

Future main() async {
  LevelDB<String, String> db = await LevelDB.openUtf8("/tmp/testdb");
  db.put("abc", "def");
  String value = db.get("abc");
  print("value is $value"); // value2 is def
}

Check out example/main.dart to see how to read, write and iterate over keys and values.

Documentation

API Documentation is available at https://www.dartdocs.org/documentation/leveldb/latest/

Isolates (Threads)

leveldb_dart supports access to a database from multiple isolates by passing shared: true to the LevelDB.open function. The LevelDB object returned by this function will share an underlying reference to the object in other isolates and changes will be visible between isolates.

See example/isolate.dart for an example of using a database from multiple isolates (OS threads).

Feature Support

  • x Read and write keys
  • x Forward iteration
  • x Multi-isolate
  • Backward iteration
  • Snapshots
  • Bulk get / put

Custom Encoding and Decoding

By default you can use LevelDB.openUtf8 to open a database with String keys and values which are encoded in UTF8. The dart:codec library can be used to create databases with custom encodings. See example/json.dart for an example which stores dart objects to the database via JSON encoding.

Libraries

leveldb