Redis Shard

A redis sharding api. Sharding is done based on the CRC32 checksum of a key or key tag ("key{key_tag}"), according to this article http://antirez.com/post/redis-presharding.html .

The source code is locate at github .

Usage

Creating a hash ring with multiple servers,By default the hash ring uses a crc32 hashing algorithm on the server's name config.You can define the name anything as you like,but it must be unique.

I don't want to bind the hashring with ipaddress,because if I do some master/slave switches, I can only change the ipaddress related config. The name is kept,so the hashring's order is kept.

>>> from redis_shard.shard import RedisShardAPI
>>> servers = [
    ...    {'name':'server1','host':'127.0.0.1','port':10000,'db':0},
    ...    {'name':'server2','host':'127.0.0.1','port':11000,'db':0},
    ...    {'name':'server3','host':'127.0.0.1','port':12000,'db':0},
    ...    {'name':'127.0.0.1:13000','host':'127.0.0.1','port':13000,'db':0},
    ...    ]
>>>
>>> client = RedisShardAPI(servers)
>>> client.set('test',1)
>>> print client.get('test')
>>> client.zadd('testset','first',1)
>>> client.zadd('testset','second',2)
>>> print client.zrange('testset',0,-1)

Hash tags

see article http://antirez.com/post/redis-presharding.html for detail.

>>> client.set('foo',2)
>>> client.set('a{foo}',5)
>>> client.set('b{foo}',5)
>>> client.set('{foo}d',5)
>>> client.set('d{foo}e',5)
>>> print client.get_server_name('foo') == client.get_server_name('a{foo}') == client.get_server_name('{foo}d') \
... == client.get_server_name('d{foo}e')

I also added an tag_keys method,which is more quickly than default keys method,because it only look one machine.

>>> client.tag_keys('*{foo}*') == client.keys('*{foo}*')

Config Format

There's three config formats

• list:

servers = [

{'name':'node1','host':'127.0.0.1','port':10000,'db':0}, {'name':'node2','host':'127.0.0.1','port':11000,'db':0}, {'name':'node3','host':'127.0.0.1','port':12000,'db':0}, ]

• dict:

servers =

{ 'node1': {'host':'127.0.0.1','port':10000,'db':0},

'node2': {'host':'127.0.0.1','port':11000,'db':0}, 'node3': {'host':'127.0.0.1','port':12000,'db':0},

}

• url_schema:

  servers = ['redis://127.0.0.1:10000/0?name=node1',

  'redis://127.0.0.1:11000/0?name=node2', 'redis://127.0.0.1:12000/0?name=node3'

  ]