menu_book Course Curriculum (MongoDB Complete Course) expand_more
$facet stage
Learn $facet stage in MongoDB through the exact construct, a dedicated example, a boundary case, and a mastery check.
$facet stage is an atomic MongoDB lesson inside Aggregation Advanced. The example uses the specific syntax, command, API, instruction, or language rule named by this lesson.
Study the construct itself, then change one relevant input and predict the result before running it. That keeps this lesson focused on $facet stage rather than on generic MongoDB syntax.
Topic-specific example
db.products.aggregate([{ $facet:{ byPrice:[{$sort:{price:1}}], count:[{$count:"n"}] } }])
Test $facet stage with an empty result, NULL/missing value, duplicate key, or concurrent operation where relevant; database behavior should be verified at the boundary shown by this example.