Redis realizes ranking function

「 This is my participation 2022 For the first time, the third challenge is 28 God , Check out the activity details ：2022 For the first time, it's a challenge 」

Preface

When I was on the consumer finance platform , The company has a special for offline sales staff APP,APP Record the Commission earned by selling and promoting the company's loan products and the functions of some store development and clock in , The backend was developed by me and another colleague , One module is the real-time ranking of sales commissions in national stores , When it comes to ranking, many people's first reaction is that this is a Top N The problem of , Take it out of the database and use it MySQL Of top The function can be implemented , In fact, we couldn't get the data from the table at that time , Data should also be matched with permissions , There are national and regional rankings , It is also necessary to calculate the effective Commission of all personnel under the regional manager , But also real-time , Reading and recalculating from the database is definitely not enough , Jump to the ranking page and wait at least 5s Left and right data can come out , Then what shall I do? , It can be released Redis in , Then let's see how to use Redis Achieve this ranking function .

One . Realize the idea

It uses Redis in zset data type ,zset The definition of is summarized here, that is, each element can be associated with a score, and it can also sort the collection elements , So this is a good place to sort , Next, let's see how to use its ranking function .

Two . Concrete realization

1. The method of adding data is wrapped

public void zAdd(String key,Object member,double score){
    try {
          redisTemplate.opsForZSet().add(key,member,score);
    } catch (Exception e) {
        log.error("redis zAdd has a error,key:{},value:{},score:{},exception:{}",key,member,score,e);
    }
}
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2. Data acquisition method packaging

public Set<Object> zRange(String key,int start,int end){
    try {
    // Take values and scores in reverse order 
        Set<ZSetOperations.TypedTuple<Object>> typedTuples = redisTemplate.opsForZSet().reverseRangeWithScores(key, start, end);
        if(typedTuples==null||typedTuples.size()==0) return null;
        return Collections.singleton(typedTuples);
    } catch (Exception e) {
        log.error("redis zRange has a error,key:{},start:{},end:{},exception:{}",
                key,start,end,e);
        return null;
    }
}
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3. The test method , Add out of order , If you want the commission from less to more, just add a minus sign before the Commission

redisUtils.zAdd("rank"," Wang Wu ",new Double("2000.00"));
redisUtils.zAdd("rank"," Zhang San ",new Double("1000.00"));
redisUtils.zAdd("rank"," Wang Ke ",new Double("4000.00"));
redisUtils.zAdd("rank"," Xiang Qiaoqiao ",new Double("6000.00"));
redisUtils.zAdd("rank"," Sha Zhenhua ",new Double("7000.00"));
redisUtils.zAdd("rank"," A lot of money ",new Double("5000.00"));
redisUtils.zAdd("rank"," Huang San ",new Double("3000.00"));
redisUtils.zAdd("rank"," Gao Qiu ",new Double("8000.00"));
redisUtils.zAdd("rank"," xu ",new Double("9000.00"));
redisUtils.zAdd("rank"," Bao Hu ",new Double("10000.00"));
// Get add into redis The data of , Using the above 2 Method 
Set<Object> rank = redisUtils.zRange("rank", 0, 9);
//todo  Get the data for other logical processing 
// Print the results 
rank.forEach(System.out::println);
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4. Execution results

[DefaultTypedTuple [score=10000.0, value= Bao Hu ],
DefaultTypedTuple [score=9000.0, value= xu ], 
DefaultTypedTuple [score=8000.0, value= Gao Qiu ],
DefaultTypedTuple [score=7000.0, value= Sha Zhenhua ],
DefaultTypedTuple [score=6000.0, value= Xiang Qiaoqiao ],
DefaultTypedTuple [score=5000.0, value= A lot of money ],
DefaultTypedTuple [score=4000.0, value= Wang Ke ], 
DefaultTypedTuple [score=3000.0, value= Huang San ], 
DefaultTypedTuple [score=2000.0, value= Wang Wu ],
DefaultTypedTuple [score=1000.0, value= Zhang San ]]
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Summary

zset In addition to the method of calculating the ranking, there is also the method of calculating the number of set conditions zcount Method , View the total number of sets zcard Methods, etc. , It's very convenient to use , But it's still the same sentence. Only in specific business can we know whether it's practical or not , And also pay attention to Redis There's a data elimination strategy , Don't ignore this point , In addition, the discarded business data is still cached in Redis Also remember to clear and check the inside .