Multi-updates/deletes against a sharded collection are sent with shard version IGNORED against the set of all nodes which the given router thinks have chunks from that collection. Because of this, the following anomalies can happen:
- The update/delete is not applied against all documents in the collection (when the router doesn't know chunk was donated to another shard, not currently included in the cache)
- The update/delete is applied multiple times on different shards for the same document (because the lack of versioning prevents them from synchronizing with chunk migration, in which case they can be applied both on the donor and the recipient)
This ticket is intended to serve as the generic catch-all of these issues.