Found!
As you see on the description, I counted the queries have been run on the DB and sorted them by number of execution.
There is a feature in every telecommunication which called read_receipt. in the Rocketchat you can disable it but still application works properly. The difference is just you can not find who has been read your text in a channel/group.
What happen when this feature is enable?!!
Assume that you have a profile and joined in at least 20 channels/groups and each one has at least 10 member in it.
for every text that sending to each channel/group, a write query is called on the DB on collection rocketchat_message_read_receipt. A 20-member-channel must updated with 20 unique query called to show you all of the members has been read your text.
In my experience, I have 3-node replica set mongoDB that has a collection rocketchat_message_read_receipt with 25 GB of size. On the other hand the total size of all messages on the DB was just 2.6 GB.
Awesome !!! or terrible feature.
