=========== Py-elevator

py-elevator is a python client for Elevator <http://github.com/oleiade/Elevator>_, a Key-Value store written in Python and based on levelDB, allows high performance on-disk bulk read/write.

Allows async, multithreaded and/or remote access to a multi-leveldb backend.

Relying on the zeromq network library and msgpack serialization format, it is made to be portable between languages and platforms.

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Requirements

• zmq-3.X
• leveldb
• pyzmq (built with zmq-3.X)
• plyvel

Debian repository

The deb.oleiade.com debian repository exposes libzmq3, libzmq3-dev, libleveldb1 and libleveldb1-dev packages in order to ease your dependencies management. Just add the following line to your /etc/apt/sources.list:

.. code-block:: bash

deb http://deb.oleiade.com/debian oneiric main

Installation

Just::

pip install py-elevator

Usage

Nota : See Elevator <http://oleiade.github.com/Elevator>_ documentation for details about server usage and implementation

Databases workaround

.. code-block:: python

from pyelevator import Elevator

Elevator server holds a default db

which the client will automatically

connect to

E = Elevator() E.db_name 'default'

You can list remote databases

E.listdb() ['default', ]

Create a db

E.createdb('testdb') E.listdb() ['default', 'testdb', ]

And bind your client to that new Db.

E.connect('testdb')

Note that you canno't connect to a db that doesn't exist yet

E.connect('dbthatdoesntexist') DatabaseError : "Database does not exist"

Sometimes, leveldb just messes up with the backend

When you're done with a db, you can drop it. Note that all it's files

will be droped too.

E.repairdb() E.dropdb('testdb')

You can even register a pre-existing leveldb db

as an Elevator db. By creating it using it's path.

E.createdb('/path/to/my/existing/leveldb') E.listdb() ['default', '/path/to/my/existing/leveldb', ]

Elevator objects can also spawn WriteBatches objects,

inheriting it's parent Elevator object configuration.

batch = E.WriteBatch()

Interact with a database:

.. code-block:: python

from pyelevator import Elevator E = Elevator() # N.B : connected to 'default'

E.Put('abc', '123') E.Put('easy as', 'do re mi') E.Get('abc') '123' E.MGet(['abc', 'easy as', 'you and me']) ['123', 'do re mi', None] E.Delete('abc') for i in xrange(10): ... E.Put(str(i), str(i))

Range supports key_from, key_to params

E.Range('1', '9') [['1','1'], ['2','2'], ['3', '3'], ['4', '4'], ['5', '5'], ['6', '6'], ['7', '7'], ['8', '8'], ['9', '9'], ]

Or key_from, limit params

E.Slice('1', 2) [['1', '1'], ['2', '2'], ]

When RangeIter only knows about key_from/key_to for py-leveldb api

compatibility reasons

it = E.RangeIter('1', '2') list(it) [['1', '1'], ['2', '2'], ]

Elevator objects supports with_statement too

with Elevator('testdb') as e: ....e.Get('1')

'1'

Batches

They're very handy and very fast when it comes to write a lot of datas to the database. See LevelDB documentation for more informations. Use it through the WriteBatch client module class. It has three base methods modeled on LevelDB's Put, Delete, Write.

.. code-block:: python

from pyelevator import WriteBatch, Elevator

Just like Elevator object, WriteBatch connects to 'default' as a default

But as it supports the exact same options that Elevator, you can

Init it with a pre-existing db

batch = WriteBatch() batch = WriteBatch('testdb')

batch.Put('a', 'a') batch.Put('b', 'b') batch.Put('c', 'c') batch.Delete('c') batch.Write()

E = Elevator() E.Get('a') 'a' E.Get('b') 'b' E.Get('c') KeyError: "Key not found"

Batches objects supports with_statement too

Write will be automatically called on exit

with WriteBatch('testdb') as batch: ....batch.Put('abc', '123') ....batch.Put('or simple as...', 'do re mi')

Code is clean and simple, don't hesitate to dig into it if you need more details about it's usage