random_DDL_CRUD_operations.js runs renameCollection with

. Thus, the destination ns must not exist, else it will fail with NamespaceExists error.

random_DDL_CRUD_operations.js attempts to ensure that won't happen by picking 'unique' destination names. It does so by appending a timestamp to the collection name. However, if done twice in the same second, the test could generate the same destination ns twice.

This could be addressed by appending a randomly generated UUID instead of a timestamp.