Transactions cannot interfere with each other.
In early versions of Cassandra, it was possible to see partial updates in a row when one user was updating the row while another user was reading that same row. For example, if one user was writing a row with two thousand columns, another user could potentially read that same row and see some of the columns, but not all of them if the write was still in progress.
Full row-level isolation is in place, which means that writes to a row are isolated to the client performing the write and are not visible to any other user until they are complete. Delete operations are performed in isolation. All updates in a batch operation belonging to a given partition key are performed in isolation.