Redis 数据库hash数据类型是一个string类型的key和value的映射表,适用于存储对象。Redis 中每个 hash 可以存储 232 - 1 键值对(40多亿)。
Python的redis模块实现了Redis哈希(Hash)命令行操作的几乎全部命令,包括HDEL、HEXISTS、HGET、HGETALL、HINCRBY、HKEYS、HLEN 、HMGET 、HMSET 、HSET 、HSETNX 、HVALS 。但是无法支持HINCRBYFLOAT 、HSCAN 等命令。
函数说明
- HDEL: 删除对应哈希(Hash)表的指定键(key)的字段,hdel(self, name, key)
- HEXISTS: 检测哈希(Hash)表对应键(key)字段是否存在,返回布尔逻辑,hexists(self, name, key)
- HGET: 获取哈希(Hash)指定键(key)对应的值,hget(self, name, key)
- HGETALL: 获取哈希(Hash)表的键-值对(key-value pairs),返回python字典类型数据,hgetall(self, name)
- HINCRBY: 为哈希表(Hash)指定键(key)对应的值(key)加上指定的整数数值(int,可为负值),参见 [Python操作Redis:字符串(String)],(http://blog.csdn.net/u012894975/article/details/51285733)hincrby(self, name, key, amount=1),Redis 中本操作的值被限制在 64 位(bit)有符号数字。
- HKEYS: 返回哈希表(Hash)对应键(key)的数组(Python称之为列表List),hkeys(self, name)
- HLEN: 获取哈希表(Hash)中键-值对(key-value pairs)个数,hlen(self, name)
- HMGET: 获取哈希表(Hash)中一个或多个给点字段的值,不存在返回nil(Redis命令行)/None(Python),hmget(self, name, keys),其中keys可以为列表(list)
- HMSET: 设置对个键-值对(key-value pairs)到哈希表(Hash)中,python输入值(mapping)为字典(dictionary)类型,hmset(self, name, mapping)
- HSET: 为哈希表(Hash)赋值,若键(key)存在值(value)则覆盖,不存在则创建,hset(self, name, key, value)
- HSETNX:为哈希表(Hash)不存值(value)的键(key)赋值,存在操作无效,对应值(value)无变化,hsetnx(self, name, key, value)
- HVALS:返回哈希表(Hash)对应值(value)的列表,hvals(self, name)
代码示例
#!/usr/bin/python
import redis
import time
## Connect local redis service
client =redis.Redis(host='127.0.0.1',port=6379,db=0)
print "Connection to server successfully!"
dicKeys = client.keys("*")
print dicKeys
### Redis hash command part Start ###
# hset: Set key to value with hash name,hset(self, name, key, value)
# hget: Return the value of ``key`` within the hash ``name``, hget(self, name, key)
client.hset('myhash','field1',"foo")
hashVal = client.hget('myhash','field1')
print "Get hash value:",hashVal
# Get none-value
hashVal = client.hget('myhash','field2')
print "None hash value:",hashVal
# hexists: Returns a boolean indicating if ``key`` exists within hash ``name``
keyList= ['field1','field2']
for key in keyList:
hexists = client.hexists('myhash',key)
if hexists :
print "Exist in redis-hash key:",key
else:
print "Not exist in redis-hash key:",key
# hgetall: Return a Python dict of the hash's name/value pairs
client.hset('myhash','field2',"bar")
valDict = client.hgetall('myhash')
print "Get python-dict from redis-hash",valDict
# hincrby: Increment the value of ``key`` in hash ``name`` by ``amount``
# default increment is 1,
client.hset('myhash','field',20)
client.hincrby('myhash','field')
print "Get incrby value(Default):",client.hget('myhash','field')
client.hincrby('myhash','field',2)
print "Get incrby value(step: 2):",client.hget('myhash','field')
client.hincrby('myhash','field',-3)
print "Get incrby value(step: -3):",client.hget('myhash','field')
# no method hincrbyfloat
#hkeys: Return the list of keys within hash ``name``
kL = client.hkeys('myhash')
print "Get redis-hash key list",kL
#hlen: Return the number of elements in hash ``name``
lenHash =client.hlen('myhash')
print "All hash length:",lenHash
#hmget: Returns a list of values ordered identically to ``keys``
#hmget(self, name, keys), keys should be python list data structure
val =client.hmget('myhash',['field','field1','field2','field3','fieldx'])
print "Get all redis-hash value list:",val
#hmset: Sets each key in the ``mapping`` dict to its corresponding value in the hash ``name``
hmDict={'field':'foo','field1':'bar'}
hmKeys=hmDict.keys()
client.hmset('hash',hmDict)
val = client.hmget('hash',hmKeys)
print "Get hmset value:",val
#hdel: Delete ``key`` from hash ``name``
client.hdel('hash','field')
print "Get delete result:",client.hget('hash','field')
#hvals: Return the list of values within hash ``name``
val = client.hvals('myhash')
print "Get redis-hash values with HVALS",val
#hsetnx: Set ``key`` to ``value`` within hash ``name`` if ``key`` does not exist.
# Returns 1 if HSETNX created a field, otherwise 0.
r=client.hsetnx('myhash','field',2)
print "Check hsetnx execute result:",r," Value:",client.hget('myhash','field')
r=client.hsetnx('myhash','field10',20)
print "Check hsetnx execute result:",r,"Value",client.hget('myhash','field10')
hashVal = client.hgetall('profile')
print hashVal
#Empty db
client.flushdb()
参考资料:
1、Redis 哈希(Hash)
2、Python redis文档(python交互模式下命令>>>help redis)