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Comment by truth_seeker | Hacker News Reader

IMO An open cursor of Change Stream with Aggregation pipeline (for given use-case) in MongoDB is more flexible solution to achieve this functionality.

In addition, it also tracks the history of changes and hence allows the cursor to go back if needed with "resumeToken"

https://docs.mongodb.com/manual/changeStreams/

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There is a big difference between a change-stream and a realtime query. For example mongodbs cursor-stream is a good way to observe the events that happen to a specific collection or documents that match some criteria. If you want the realtime-results of a query that has sorting, skip limit etc. than it is really hard to warp the changestream into this. In fact this is exactly what EventReduce could do for you.

For more information about the difference I recommend the video "Real-Time Databases Explained: Why Meteor, RethinkDB, Parse & Firebase Don't Scale" https://www.youtube.com/watch?v=HiQgQ88AdYo&t=1703s

>> There is a big difference between a change-stream and a realtime query. For example mongodbs cursor-stream is a good way to observe the events that happen to a specific collection or documents that match some criteria. If you want the realtime-results of a query that has sorting, skip limit etc. than it is really hard to warp the changestream into this.

Have you actually tried it from mongo shell or any mongodb client driver ?

In the official document link which i shared it is clearly mentioned it supports aggregation pipeline. Any operator which is compatible with aggregation pipeline framework including "$sort" and "$skip" can be used. You can also use JOIN like operator "$lookup" or "$graphLookup".

See this link for info https://docs.mongodb.com/manual/core/aggregation-pipeline-op...

Yes I used it. I actually know it really well. I also did performance comparisons with mongodb and mongodbs change stream and cursors. What I posted here is just an algorithm. You could now compare it to mongodb (a product) and say it is a "more flexible solution" but I do not see the point in directly comparing it simply based on the documentation of both.

>> Yes I used it. I actually know it really well. I also did performance comparisons with mongodb and mongodbs change stream and cursors.

Can you share the link for the code and data in Database against which you are querying to prove your claim ?

No and I also do not want to "claim" something. Feel free to do your own tests.

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