rkvs - Simple Erlang Key/Values interface

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.