Redis基础教程之Redis排序

本篇文章介绍下redis排序命令.redis支持对list，set和sorted set元素的排序。排序命令是sort 完整的命令格式如下： 
SORT key [BY pattern] [LIMIT start count] [GET pattern] [ASC|DESC] [ALPHA] [STORE dstkey]  
下面我们一一说明各种命令选项 
（1）sort key 
这个是最简单的情况，没有任何选项就是简单的对集合自身元素排序并返回排序结果.下面给个例子

redis> lpush ml 12
(integer) 1
redis> lpush ml 11
(integer) 2
redis> lpush ml 23
(integer) 3
redis> lpush ml 13
(integer) 4
redis> sort ml
1. "11" 2. "12" 3. "13" 4. "23"

(2)[ASC|DESC] [ALPHA] 
sort默认的排序方式（asc）是从小到大排的,当然也可以按照逆序或者按字符顺序排。逆序可以加上desc选项，想按字母顺序排可以加alpha选项，当然alpha可以和desc一起用。下面是个按字母顺序排的例子

redis> lpush mylist baidu
(integer) 1
redis> lpush mylist hello
(integer) 2
redis> lpush mylist xhan
(integer) 3
redis> lpush mylist soso
(integer) 4
redis> sort mylist
1. "soso" 2. "xhan" 3. "hello" 4. "baidu" redis> sort mylist alpha
1. "baidu" 2. "hello" 3. "soso" 4. "xhan" redis> sort mylist desc alpha
1. "xhan" 2. "soso" 3. "hello" 4. "baidu"

redis> set name11 nihao
OK
redis> set name12 wo
OK
redis> set name13 shi
OK
redis> set name23 lala
OK
redis> sort ml by name* 
1. "13" 2. "23" 3. "11" 4. "12"

redis> sort ml by name* get name*  alpha
1. "lala" 2. "nihao" 3. "shi" 4. "wo"

redis> sort ml by name* get name* get #  alpha
1. "lala" 2. "23" 3. "nihao" 4. "11" 5. "shi" 6. "13" 7. "wo" 8. "12"

redis> hset user1 name hanjie
(integer) 1
redis> hset user11 name hanjie
(integer) 1
redis> hset user12 name 86
(integer) 1
redis> hset user13 name lxl
(integer) 1
redis> sort ml get user*->name
1. "hanjie" 2. "86" 3. "lxl" 4. (nil)

redis> sort ml get name* limit 1 2
1. "wo" 2. "shi"

redis> sort ml get name* limit 1 2 store cl
(integer) 2
redis> type cl
list
redis> lrange cl 0 -1
1. "wo" 2. "shi"

redis> sadd tom:friend:list  123 #tom的好友列表 里面是好友的uid 
1 
redis> sadd tom:friend:list  456 
1 
redis> sadd tom:friend:list  789 
1 
redis> sadd tom:friend:list  101 
1 
redis> set uid:sort:123 1000 #uid对应的成绩 
OK 
redis> set uid:sort:456 6000 
OK 
redis> set uid:sort:789 100 
OK 
redis> set uid:sort:101 5999 
OK 
redis> set uid:123 "{'uid':123,'name':'lucy'}" #增加uid对应好友信息 
OK 
redis> set uid:456 "{'uid':456,'name':'jack'}" 
OK 
redis> set uid:789 "{'uid':789,'name':'marry'}" 
OK 
redis> set uid:101 "{'uid':101,'name':'icej'}"  
OK 
redis> sort tom:friend:list by uid:sort:* get uid:* #从好友列表中获得id与uid:sort字段匹配后排序,并根据排序后的顺序，用key在uid表获得信息 
1. {'uid':789,'name':'marry'} 
2. {'uid':123,'name':'lucy'} 
3. {'uid':101,'name':'icej'} 
4. {'uid':456,'name':'jack'} 
redis> sort tom:friend:list by uid:sort:* get uid:* get uid:sort:* 
1. {'uid':789,'name':'marry'} 
2. 100 
3. {'uid':123,'name':'lucy'} 
4. 1000 
5. {'uid':101,'name':'icej'} 
6. 5999 
7. {'uid':456,'name':'jack'} 
8. 6000

if (alpha) { if (sortby) vector[j].u.cmpobj = getDecodedObject(byval);
} else { if (byval->encoding == REDIS_ENCODING_RAW) {
    vector[j].u.score = strtod(byval->ptr,NULL);
} else if (byval->encoding == REDIS_ENCODING_INT) { /* Don't need to decode the object if it's  * integer-encoded (the only encoding supported) so  * far. We can just cast it */ vector[j].u.score = (long)byval->ptr;
} else {
    redisAssert(1 != 1); 
}   
}