Redis-哈希

简介

REmote DIctionary Server(Redis)是一个开源的使用 ANSI C 语言编写、遵守 BSD 协议、支持网络、可基于内存、分布式、可选持久性的键值对(Key-Value)存储数据库，并提供多种语言的 API。Redis运行在内存中 但是可以持久化到磁盘，所以在对不同数据集进行高速读写时 需要权衡内存，因为数据量不能大于硬件内存。

Redis的数据结构类型(Redis值value的类型)有5种：string（字符串），hash（哈希），list（列表），set（集合）及zset(sorted set：有序集合)。

字符串的一个键 最大能存储 512MB。
每个 hash 可以存储 2^32 -1 键值对（40多亿）。
列表最多可存储 2^32 - 1 元素 (4294967295, 每个列表可存储40多亿)。
集合最大的成员数为 2^32 - 1(4294967295, 每个集合可存储40多亿个成员)。

http://redisdoc.com/index.html
redis-cli -h host -p port -a password

Python包

pip install redis-py-cluster==2.1.0

#!/bin/python3
# -*- coding:utf-8 -*-
import os, sys
import json
import copy

from rediscluster import RedisCluster


class RedisClient:
    def __init__(self, config):
        self._config = copy.deepcopy(config)
        self._startup_nodes_list = self._config.nodes_list
        self._password = self._config.redis_password
        self.redis = RedisCluster(startup_nodes=self._startup_nodes_list,
                                  password=self._password, decode_responses=True, socket_timeout=5)

    def hsetnx(self, key, field, value, timeout=None):   # set_new_field field已经存在，该操作无效
        self.redis.hsetnx(key, field, value)

        if isinstance(timeout, int):
            self.redis.expire(key, timeout)   

    def hset(self, key, field=None, value=None, mapping=None, timeout=None):   # field已经存在于哈希表中，旧值将被覆盖
        if not field is None:
            return self.redis.hset(key, field, value)   # 一个key的单个filed:value添加
        elif not mapping is None:
            print('=====mapping=====', field, value, mapping)
            return self.redis.hset(key, None, None, mapping)   # 一个key的多个{fields:values}添加
        
        if isinstance(timeout, int):
            self.redis.expire(key, timeout)

    def expire(self, key, timeout):   # 对key执行命令的超时限制判断
        if not isinstance(timeout, int):
            raise ValueError("timeout must be integer")
        self.redis.expire(key, timeout)

    def hget(self, key, field): 
        value = self.redis.hget(key, field)
        return "" if value is None else str(value)

    def hgetall(self, key):
        value = self.redis.hgetall(key)
        return "" if value is None else str(value) 

    def hexists(self, key, field):   # 判断key的指定field是否存在
        return self.redis.hexists(key, field)

    def hdel(self, key, field):   # 删除key的指定field [单个field]
        if self.redis.hexists(key, field):
            return self.redis.hdel(key, field)
        else: pass
	#def hdel(self, key, fields): # 删除key的指定field key(string), fields=(filed1name,field2name,field3name, ...)
    # return self.redis.hdel(key, *fields)
     
    def close(self):
        self.redis.close()


class config:
    def __init__(self, _nodes_list, redis_password):
        self.nodes_list = _nodes_list
        self.redis_password = redis_password



if __name__=="__main__":
    conf = config([{
    'host':'redis.db.cloud', 'port':'10009'}],
                  '123456')
    client = RedisClient(conf)

    user_table = 'user_feature1_'
    item_table = 'item_feature1_'

    uid_key = user_table + '7db9ca895802365'
    uid_field = 'user_behavior_timezone'
    print('the uid_key is : %s, uid_field is : %s' % (uid_key, uid_field))
    
    print('test_hgetall_ing......')
    print(client.hgetall(uid_key))
    print('\n') 
    
    print('test_hexists_ing......')
    print(client.hexists(uid_key, uid_field))
    print('test_hget_ing......')
    print(client.hget(uid_key, uid_field))
    print('\n')
    
    print('test_hset_ing......')
    print(client.hset(uid_key, uid_field, 'N8'), 'after_change_field: ', client.hget(uid_key, uid_field))
    print(client.hset(uid_key, None, None, mapping={
    uid_field: '8'}), 'recover_field: ', client.hget(uid_key, uid_field))
    print('\n')
    
    print('test_hdel_ing......')
    print(client.hset(uid_key, uid_field, '8'), '%s is exists: ' % uid_field, client.hexists(uid_key, uid_field), client.hdel(uid_key, uid_field))       
    print('after hdel %s is exist: '% uid_field, client.hexists(uid_key, uid_field), client.hset(uid_key, uid_field, '8'))

    client.close()