emongo

MongoDB driver for erlang rewritten from erlang-mongo-driver

Why emongo

Emongo is developed using NIF binding instead of pure native implementation. this maintains upstream client changes as well as server version compatibility.

• Emongo supports multi-tenantancy out of the box.
• It uses C++ based mongocxx pools for connection pools , reducing thread management overhead.
• Performant erlang mongo client.
• Simple API's in terms with mongo client API's.

Design principle

Starts a different erlang pid for each tenant using poolboy. Each tenant then creates its own connection pool. To avoid VM blocking NIF's are written as ERL_NIF_DIRTY_JOB_IO_BOUND

Usage

Compile emongo

./rebar get-deps
./rebar compile

Run erlang
erl -pa ebin deps/poolboy/ebin

%% Start emongo app with default connection/tenant.
emongo:start("mongodb://localhost/db").

%% Find all documents in a collection
emongo:find_all("collection").

%% Find all documents in a collection with find options.
emongo:find_all("collection",#{limit=>23}).

%% Add a tenant 
emongo:add_tenant(tenant1,"mongodb://localhost/t1db").

%% Find all documents in a collection for tenant1
emongo:find_all(tenant1,"collection").

Alternatives

• erlang-mongo-driver

Note

I have little knowledge with C/C++ so would encourage someone to look at the C++ code that is written to make sure I have written it in a good way.