Why i can't see any benefit of implementing Redis to my api?

[xts-bit]

Description

Redis is known for its speed, and popular applications like Instagram rely on Redis for optimal performance. However, when I integrated Redis into my API, I observed that it only marginally improved the response time. Initially, my regular API, which uses MongoDB, responded with an average of 302ms. After implementing Redis, the response time decreased to an average of 298ms.

Now, I'm seeking guidance on the proper implementation of Redis in my Node.js API. Could you please provide some advice on how to achieve optimal utilization of Redis within my API?

(async () => {
  await redisClient.connect();
})();

redisClient.on('connect', () => console.log('::> Redis Client Connected'));
redisClient.on('error', (err) => console.log('<:: Redis Client Error', err));

router.get('/posts', async (req, res) => {
  try {
    const numBuckets = 10;
    const cacheTTL = 60;
    const bucketIndex = Math.floor(Math.random() * numBuckets);
    const cacheKey = `posts:${bucketIndex}:${req.query.page || 1}`;
    const cachedData = await redisClient.json.get(cacheKey, '$');
    if (cachedData) {
      console.log('Data fetched from Redis cache');
      return res.json(cachedData);
    }
    const limit = 30
    const page = Number(req.query.page) || 1;
    const skip = (page - 1) * limit;
    const result = await User.aggregate([
      { $project: { _id: 0, username: 1, profileImg: 1, posts: 1 } },
      { $unwind: '$posts' },
      { $project: { postImage: '$posts.post', date: '$posts.date', username: 1, profileImg: 1 } },
      { $sort: { [bucketIndex % 2 === 0 ? 'date' : 'postImage']: bucketIndex % 2 === 0 ? -1 : 1 } },
      { $skip: skip },
      { $limit: limit },
    ]);
    await Promise.all([
      redisClient.json.set(cacheKey, '$', result),
      redisClient.expire(cacheKey, cacheTTL)
    ]);
    console.log('Data fetched from MongoDB and cached in Redis');
    res.json(result);
  } catch (err) {
    console.error(err);
    res.status(500).json({ message: 'Internal server error' });
  }
});

Node.js Version

v20

Redis Server Version

Redis Labs

Node Redis Version

4.6.7

Platform

MacOS

Logs

No response

[avinashkrishna613]

One issue i see is, for every GET api call, you are generating a cacheKey based on random bucketIndex and hence i don't think your code reaches to this point at any time

if (cachedData) {
      console.log('Data fetched from Redis cache');
      return res.json(cachedData);
 }

[uglide]

In addition to @avinashkrishna613 valid point, your TTL value probably is too low for the number of requests that you get for each "bucket".

[xts-bit]

@uglide I am trying to retrieve some posts from my MongoDB database but it was taking a lot of time to get posts to I implemented Redis caching in my API but now I am facing a problem that it's returning the same posts from the cache every time I hit the API How to get new and different posts from redis cache whenever I hit the API? Instagram uses Redis and they give me new and different posts every time I scroll so fast How to balance things in my case?

What can be a better approach to solve this problem with the API?