The cursor response, which represents the files to copy, will have a new field added named required: <bool>, indicating whether the file must be copied regardless of choice when taking a selective backup.

The following files not associated with a namespace will be marked as required:

• WiredTiger
• WiredTiger.backup
• WiredTigerHS.wt
• WiredTigerLog.*
  • Journal files.
• _mdb_catalog.wt
• sizeStorer.wt
• Any collection residing in an internal database (admin, local or config).
• Each databases system.views collection. This is necessary for time-series collections to be properly restored.
• Files with table logging enabled. These need to be copied otherwise WiredTiger will return an error when running recovery.