MySQL (and other Relational Databases) are known to be ACID compliant with respect to transactions. However, when databases are sharded, does the ACID property of transactions break since now transactions cannot be handle by the db, since the shards are now completely different db instances. Does this mean, the transactions should be handled at the application level including implementation of rollback and other features? So, how does sharding effects ACID property and how to overcome if there any disadvantages of the same?
PS: MongoDB from version 4.2 supports transactions across sharded clusters? Does this give MongoDB a considerable edge over MySQL (and RDMs)?