@Prasad_Saya Thank you so much for your answer !
Actually, i have a little bit unclearly about performance, exactly PERFORMANCE of READ query if array of comment objectID is large, maybe UNBOUNED. And I just don’t know the comparision performance of two scenarior - to read amounts of comment of a post:
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Using lookup if store array comment objectID in post ( I’m worry about performance here because I saw from document: Each objectID need to travel to comment collection one, so array of 10000 objectID will need to travel comment collection 10000 times, or maybe I misunderstand this ??? )
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Just store postID in each comment, then using only ONE query. Is this better performance than lookup above ?.
And of course, there are other CRUD operator, but I just focus on READ operator.
Can you explain to me more about lookup operation, thank u !