Is there a way to collocate documents of different collections on to the same shard?

Working with Data
1

Hi, we need to run transactions across multiple documents from different collections, and these collections are all sharded with the same sharding key. Is there a way to collocate the documents with the same sharding key from different collections on to the same shard so that the transactions do not span multiple shards?

Also I imagine running transactions in one shard is more preformant than running it across multiple shards, but how much a difference is it?

2

I am also finding such feature. if mongodb support this then there are many possibilities.
such as $lookup on sharded collections.