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rkvs - Simple Erlang Key/Values interface

Copyright (c) 2014-2015 Benoît Chesneau.

Version: 0.2.1

rkvs is a simple Key-Value database interface. It offers for now a frontend to the following K/V storages: ets, leveldb, rocksdb, hanoidb, bitcask.

Example of usage

Enable a backend

To enable one of the backend, add one of the following line to your rebar or make the depency availavle in ERL_LIBS:

    {leveldb, ".*", {git, "https://github.com/basho/eleveldb.git",
                     {tag, "2.1.0"}}},

    {erocksdb, ".*", {git, "https://github.com/leo-project/erocksdb.git",
                      {branch, "develop"}}},

    {hanoidb, ".*", {git, "https://github.com/krestenkrab/hanoidb.git",
                     "4e82d5f81ab087f038bfd13354ff48ee9113f459"}},

    {bitcask, ".*", {git, "https://github.com/basho/bitcask.git",
                     {tag, "2.0.0"}}},

Create a database:

Name = "mydb",
{ok, Engine} = rkvs:open(Name, [{backend, rkvs_leveldb}]).

5 backends are available:

• rkvs_ets: ETS backend
• rkvs_leveldb: LevelDB backend using eleveldb from Basho.
• rkvs_rocksdb: rocksdb backend using erocksdb.
• rkvs_hanoidb: hanoidb backend
• rkvs_bitcask: bitcask backend

Store a values

Storing a value associated to a key using rkvs:put/3:

Key = <<"a">>,
Value = 1,
ok =  rkvs:put(Engine, Key, Value).

Retrieve a value

Use the rkvs:get/2 function to retrieve a value.

Value = rkvs:get(Engine, Key).

Value should be 1

Note: you can use rkvs:contains/2.

Delete a value

Use rkvs:clear/2 to delete a value:

ok = rkvs:clear(Engine, Key).

Store and write multiples values in one pass:

Using rkvs:write_batch/2 you can write and delete multiple values in one pass:

ok =  rkvs:write_batch(Engine, [{put, <<"a">>, 1},
                                {put, <<"b">>, 2},
                                {put, <<"c">>, 3}]),

ok =  rkvs:write_batch(Engine, [{put, <<"d">>, 4},
                                {delete, <<"b">>},
                                {put, <<"e">>, 5}]).

Retrieve multiple values in a range:

Use rkvs:scan/4 to retrieve multiples K/Vs as a list:

Result = rkvs:scan(Engine, first, nil, 0).

Result should be [{<<"a">>,1},{<<"c">>,3},{<<"d">>,4},{<<"e">>,5}]

Use rkvs:fold/5 to pass a function to keys in a range instead of retrieving all the values as a list. rkvs:clear_range/4 can be used to clear all the values in a range.

Close a storage

Close a storage using rkvs:close/1:

rkvs:close(Engine)

You can use rkvs:destroy/1 to close and delete the full storage

Ownership and License

The contributors are listed in AUTHORS. This project uses the MPL v2 license, see LICENSE.

rkvs uses the C4.1 (Collective Code Construction Contract) process for contributions.

Development

Under C4.1 process, you are more than welcome to help us by:

• join the discussion over anything from design to code style try out
• and submit issue reports
• or feature requests pick a task in
• issues and get it done fork
• the repository and have your own fixes send us pull requests and even
• star this project ^_^

To run the test suite:

make test

Modules