Answer
$unwind expands array fields into multiple documents so pipeline stages can analyze individual elements.
Quick Answer
$unwind deconstructs an array field - for each element in the array, it outputs a separate document. Example: a product document with a sizes array [S, M, L] becomes three documents, one per size. Necessary when you want to group, filter, or sort by individual array elements in an aggregation pipeline.
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SugharaIQ Editorial Team
Verified Answer
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Source: SugharaIQ