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MongoDB C100DBA Exam - Topic 8 Question 104 Discussion

Actual exam question for MongoDB's C100DBA exam
Question #: 104
Topic #: 8
[All C100DBA Questions]

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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Audry
3 months ago
It's 2 documents, but the traits are what counts!
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Yuriko
3 months ago
Wait, how can it be 5? That seems off.
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Jess
3 months ago
Definitely 5, no doubt about it!
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Stephaine
4 months ago
I think it should be 4, right?
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Vanna
4 months ago
There are 5 traits in total.
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Kenny
4 months ago
I recall that if each document has traits, the total output should match the sum of traits across both documents. I think that might lead to 4 documents if I remember correctly.
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Leonie
4 months ago
I feel like I might be mixing up the total number of traits with the documents. I need to double-check how many traits are in each document.
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Honey
4 months ago
I think we practiced a similar question where $unwind increased the document count based on array length. If there are 3 traits total, then it would be 5 documents.
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Arlyne
5 months ago
I remember that $unwind duplicates documents for each element in the array, but I'm not sure how many traits there are in this case.
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Stephen
5 months ago
I think I've got it! The $unwind stage will take the 2 documents in the collection and split each one into separate documents, one for each element in the "traits" array. Since each document has 2 traits, the total number of documents passed to the next stage will be 4.
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Sabina
5 months ago
Alright, let's break this down step-by-step. The collection has 2 documents, and each document has an array of "traits" with 2 elements. When we use the $unwind stage, it will split each document into separate documents, one for each element in the "traits" array. So the final number of documents passed to the next stage should be 4.
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Margot
5 months ago
I'm a bit confused here. The question mentions "only 2 documents" in the collection, but the options include answers like 3 and 5. I'll need to double-check the data structure and the $unwind behavior to make sure I understand this correctly.
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Therese
5 months ago
Okay, I think I've got this. The $unwind stage will split each document into multiple documents, one for each element in the "traits" array. Since there are 2 documents in the collection, and each document has 2 traits, the total number of documents passed to the next stage should be 4.
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Fernanda
5 months ago
Hmm, let me think this through. The question is asking about the number of documents that will be passed to the next stage after using the $unwind stage. I'll need to carefully analyze the data structure and the effect of $unwind to determine the correct answer.
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Yvonne
1 year 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
1 year ago
I agree with C) 4. Can't wait to see the results!
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Isadora
1 year ago
I'm going with A) 3. Let's unwind those documents!
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Cristy
1 year ago
I think it's D) 2. Let's see if we're right!
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Nobuko
1 year 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
1 year ago
That's a good point, we should always be cautious of potential edge cases in our queries.
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Laquanda
1 year ago
I think we need to consider all possibilities before choosing the answer.
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Christiane
1 year 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
1 year 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
1 year 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
1 year ago
User4: A) 3 seems to be the correct answer then.
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Francis
1 year ago
User3: So, the next stage will receive 3 documents in total.
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Jannette
1 year ago
User2: Yeah, I agree. The unwind operation will split the 'traits' array into 3 documents.
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Jeannetta
1 year ago
User1: I think the answer is A) 3
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Paris
1 year 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
1 year 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
1 year ago
Yes, the unwind operation just flattens the 'traits' array within each document.
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Sean
1 year ago
I agree, the answer is D) 2.
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Emily
1 year ago
I disagree, I believe the answer is A) 3.
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Gertude
1 year 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
1 year 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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Jess
1 year ago
You're welcome!
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Selma
1 year ago
I would have guessed D) 2.
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Shala
1 year ago
Oh, I see. Thanks for clarifying.
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Marjory
1 year ago
No, it's actually C) 4.
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Linsey
1 year ago
Oh, I see. Thanks for clarifying.
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Elden
1 year ago
I think the answer is A) 3.
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Solange
1 year ago
No, it's actually C) 4.
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Elliott
1 year ago
I think the answer is A) 3.
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Paris
1 year ago
I think the answer is C) 4.
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