We are facing the error "Btree::insert: key too large to index" when trying to delete a document, and the document is not deleted with success. I know that this error is caused by the index entry for this document exceeds index key limit, as described in the doc: https://docs.mongodb.com/manual/reference/limits/#Index-Key-Limit .

My question is that why this document was inserted into the database without error. As the document https://docs.mongodb.com/manual/reference/limits/#Index-Key-Limit  says, inserting this document to the mongodb should be failed.