MongoDB Exam C100DBA Topic 8 Question 104 Discussion

Actual exam question for MongoDB's C100DBA exam

Question #: 104
Topic #: 8

Suposse tou have the following collection with only 2 documents:

If you run an aggregation query and use { $unwind: "$traits" } as the first stage, how many documents will be passed to the next stage of the aggregation pipeline?

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Suggested Answer: B

by Lynelle at Dec 05, 2024, 06:19 AM

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Yvonne

3 months ago

I'm going with C) 4. Unwind that data baby, unwind it good! Though I do wonder, what kind of traits are we talking about here? Superpowers? Fashion sense? The suspense is killing me!

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Giovanna

2 months ago

I agree with C) 4. Can't wait to see the results!

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Isadora

2 months ago

I'm going with A) 3. Let's unwind those documents!

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Cristy

3 months ago

I think it's D) 2. Let's see if we're right!

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Nobuko

3 months ago

Wait, is this a trick question? What if the 'traits' array is actually empty in one of the documents? Then the answer would be E) 1. Gotta watch out for those hidden gotchas!

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Hershel

3 months ago

That's a good point, we should always be cautious of potential edge cases in our queries.

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Laquanda

3 months ago

I think we need to consider all possibilities before choosing the answer.

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Christiane

3 months ago

True, if the 'traits' array is empty in one of the documents, only 1 document will be passed to the next stage.

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Aimee

3 months ago

I agree with Paris, the correct answer is C) 4 because each document will be duplicated for each element in the 'traits' array.

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Luisa

3 months ago

C'mon, this is easy! The answer has to be A) 3. The unwind operation will split the 'traits' array, but there are only 3 unique elements in the entire collection.

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Madalyn

2 months ago

User4: A) 3 seems to be the correct answer then.

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Francis

2 months ago

User3: So, the next stage will receive 3 documents in total.

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Jannette

3 months ago

User2: Yeah, I agree. The unwind operation will split the 'traits' array into 3 documents.

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Jeannetta

3 months ago

User1: I think the answer is A) 3

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Paris

3 months ago

But if you unwind the 'traits' array, each document will create a new document for each element in the array, so it should be 4.

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Joseph

4 months ago

Hmm, I think the answer is D) 2. The unwind operation shouldn't create any new documents, it should just flatten the 'traits' array within each of the original 2 documents.

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Della

3 months ago

Yes, the unwind operation just flattens the 'traits' array within each document.

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Sean

3 months ago

I agree, the answer is D) 2.

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Emily

4 months ago

I disagree, I believe the answer is A) 3.

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Gertude

4 months ago

I'm pretty sure the answer is B) 5. The unwind operation should create 5 documents, one for each element in the 'traits' array across the 2 original documents.

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Asha

4 months ago

The answer is clearly C) 4. The unwind operation will split each document into individual elements of the 'traits' array, so the original 2 documents will become 4 documents.

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