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I have a MongoDB collection (let's call it myColl) with around 1000 documents like following:

{ 
   "_id" : ObjectId("5e94b03a8397f71c25d95abb"), 
   "name" : "NameExample" 
}

I want to get 10 random and unique documents from myColl, and actually I'm doing it in this way:

db.myColl.aggregate(
   [ { $sample: { size: 10 } } ]
)

But today I read in the documentation that $sample may output the same document more than once in its result set (source: https://docs.mongodb.com/manual/reference/operator/aggregation/sample/). Does it mean that in my case I can get the same document twice (or even more)? If yes, what is the most efficient way to get random and unique results?

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