FlatDB

FlatDB is a thin HTTP wrapper around LevelDB. LevelDB is a simple, persistent key-value store.

API

There are three endpoints. Each accepts multiple values at a time. All use HTTP GET. (This is not a RESTful interface.)

/get

GET /get?key=foo&key=bar HTTP/1.1

Get one or more values from the database. The response will be a JSON object with a key for each key found in the database.

/getblob

GET /getblob?key=foo HTTP/1.1

Retrieve the contents of the key and return it as binary.

/getrange

GET /getrange?from=from_key HTTP/1.1

Get a range starting at from_key.

/put

GET /put?foo=bar&baz=qux HTTP/1.1

Store one or more values in the database. If multiple key/value pairs are specified, they will be written atomically as a batch. If the write succeeds, the return status will be 201. If the write fails, it will not.

/putblob

PUT /putblob?key=foo HTTP/1.1

Store the contents of the request in the key sent as parameter. If the write succeeds, the return status will be 201. If the write fails, it will not.

/delete

GET /delete?key=foo&key=baz HTTP/1.1

Delete one or more keys from the database. If multiple keys are specified, they will be deleted atomically as a batch. If the delete succeeeds, the return status will be 200.

Why FlatDB?

LevelDB is an ideal solution for a persistent, fast key-value store. (RocksDB is an alternative from Facebook that has a lot in common, but is also very new.) Since LevelDB (and RocksDB) is a library-level data store, FlatDB provides a simple, service-oriented interface to it.

Other projects, like RevelDB and the Python leveldb-server package, provide similar functionality, but:

• RevelDB barely built and then segfaulted on startup.
• leveldb-server is weird and tornadoy and undocumented.

Running FlatDB

FlatDB installs two executable scripts: flatdb and flatdb-dev.

$ flatdb -h
usage: flatdb [-h] [-d] [-p PORT] [-b DATABASE] [-H HOST]

optional arguments:
  -h, --help            show this help message and exit
  -d, --debug
  -p PORT, --port PORT
  -b DATABASE, --database DATABASE
  -H HOST, --host HOST

--port:

Port to listen on. (7532)

--host:

Address to bind to. (127.0.0.1)

--database:

Path to a LevelDB (will be created if it doesn't exist).

flatdb runs a gevent server. flatdb-dev runs the built-in Flask server.