Discuss MongoDB C100DBA Exam Topic 7 Question 131

Consider the following document from the products collection:

What does the following query using $elemMatch return? db.products.find( { product_code: "345678" }, { variations: { $elemMatch: { size: ^L^ } } } )

AReturns the complete document but retrieves only the size field from the array

BReturns the document but with only one element in the variations array (corresponding to size L)

CReturns the complete document since MongoDB does not support partial array retrieval

DReturns the complete document but retrieves only the size field from the array and also with only one element in the variations array (corresponding to size L)

Suggested Answer: B

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21 comments · newest first

Maurine 2 days ago

I think it's B.

Lilli 7 days ago

I hope I get this right!

Mozell 12 days ago

Agreed, B makes sense for clarity.

Walton 17 days ago

Still, B is the most straightforward answer.

Serina 22 days ago

But D includes size field retrieval.

Lilli 28 days ago

D is too complicated. Just one element is enough.

Jackie 1 month ago

C seems wrong. It retrieves specific fields.

Mozell 1 month ago

A doesn't limit the array though.

Serina 1 month ago

I feel like it could be A too.

Walton 2 months ago

It matches size L, so only that variation shows up.

Jackie 2 months ago

Why B?

Walton 2 months ago

I think it's B.

Denae 2 months ago

A is misleading, it doesn't just retrieve the size field.

Carry 2 months ago

C is incorrect, it can return specific elements!

Terrilyn 2 months ago

Wait, does MongoDB really not support partial array retrieval?

Bobbye 3 months ago

Definitely B! Makes the most sense.

Rebbeca 3 months ago

I think it returns the document with just one variation for size L.

Audrie 3 months ago

I feel like option D might be the right choice since it mentions retrieving the size field and only one element, which seems to align with how $elemMatch works.

Becky 3 months ago

I’m a bit confused about whether MongoDB allows partial retrieval of arrays. I thought it did, but I could be wrong.

Claribel 3 months ago

I remember practicing a similar question where $elemMatch was used, and it returned only the matching elements from the array. So, I’m leaning towards option B.

Dorathy 4 months ago

I think the query is supposed to return the document with just the matching variation, but I'm not entirely sure if it includes the whole document or just part of it.

MongoDB C100DBA Exam - Topic 7 Question 131 Discussion