Wildcard expressions in a filename can only be used when reading GCS objects. Wildcard characters in an object name can be specified by using the wildcard characters * or ? in the Prefix name or Object name.
GCS objects are selected using the same rules as in the Unix shell. Filenames matching the wildcard file specifications are added in the job log, and data from each file whose name matches the wildcard expressions will be read.
Wildcard expressions that match a "/" in the object name with a wildcard character will be skipped. For example, '/ab*' will not match '/abc/xyz'. You can enter /alph*/* to match /alphabet/a, /alphabet/b, and so on. This is the same behavior that you would expect from GLOB during shell filename expansion.
Prefix and Object are concatenated before expansion. Wildcard characters can appear in either. Wildcards that do not match any objects will show the correct pattern in the error response.