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I have a collection with repeated values for columns in the documents. I want to query for distinct values of multiple fields(System, subsystem) combination. Below is a sample data:

"System" : "training", "subsystem": "user", "ccid": "post", ret: 0
"System": "training", "subsystem": "user", "ccid": "test", ret: 1
"System": "training", "subsystem ":"cour", "ccid":"sample", ret:0

I tried to use the aggregate from the other links, but it's not resolving in java for me. Could you please share me a sample java code using aggregate or map-reduce or any of the suitable methods

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  • Have you tried using $group Commented Dec 31, 2022 at 10:29
  • Could you please share the java syntax of aggregate group for this scenario? I tried, but couldn't get the correct syntax Commented Jan 1, 2023 at 5:10
  • This might help: stackoverflow.com/questions/42814325/… Commented Jan 1, 2023 at 19:04
  • @Joe: I don't have a class defined for the structure. Could you share me a simple java query including aggregate group of 2 fields and projection fields? Commented Jan 2, 2023 at 11:22
  • I have formed this query: cursor1= CollSubsystem.aggregate(Arrays.asList(Aggregates.match(filter),Aggregates.project(SubSystemFields))).iterator() ; In order to add group iteria, it's expecting BSON Format, i tried addfields also -> that's expecting field format. Please advise. Commented Jan 2, 2023 at 13:04
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