$facet with sharded collection

The section “Aggregation Pipeline on a Sharded Cluster” indicates that the $facet pipeline stage will run on the primary shard.

When looking at the documentation:
https://docs.mongodb.com/manual/core/aggregation-pipeline-sharded-collections/?jmp=university

There are references to $out and $lookup running on the primary shard but I don’t see $facet.

Can you clarify if $facet does run on the primary shard? Thank you!

Thank you!

@ Mark_37524

I can assure you that the Lecture is correct.