Redis®*: Technical validations

This documentation is part of the Rank users in real time guide. You can view the complete guide here: Learn how to rank 2 million users by score in real time using Redis.

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• Redis Commander web UI included.
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Sorted sets combine a key and a score. In our case, the key is the user ID and the score represents the user's points.

We began by launching a Redis service on Stackhero. The service is up in just 2 minutes with the latest stable release, offers hourly billing, and features Redis Commander, a handy web GUI. We validated the concept using this interface.

We added three users with sample IDs and scores as shown below:

| Username | Score | | - | - | | userId1 | 11 | | userId2 | 54 | | userId3 | 24 |

These users were added to a sorted set called usersScores using the following Redis commands:

ZADD usersScores 11 "userId1"
ZADD usersScores 54 "userId2"
ZADD usersScores 24 "userId3"

Redis Commander, the web GUI provided on Stackhero with Redis instances

Next, we retrieved userId1's score:

ZSCORE usersScores "userId1"
> 11

This confirmed that the score for userId1 was indeed 11. After that, we checked userId1's rank:

ZREVRANK usersScores "userId1"
> 2

Remember, ranking starts at 0. This means that the rankings are as follows:

| Username | Score | Rank | | - | - | - | | userId1 | 11 | 2 | | userId2 | 54 | 0 | | userId3 | 24 | 1 |

The command ZREVRANK returned 2, which is exactly what we expected for userId1.

You can also fetch the top entries. For example, to retrieve the first 2 users (from rank 0 to rank 1) run:

ZREVRANGE usersScores 0 1 WITHSCORES
> 1) userId2
> 2) 54
> 3) userId3
> 4) 24

To get the top 100 users simply run:

ZREVRANGE usersScores 0 99 WITHSCORES

This approach is efficient and perfectly suited to high-performance real-time ranking.