Wildcard expressions in an object name can only be used in the data import scenario, where data is loaded into the database after being read from objects in GCS. 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. Object names matching the wildcard specifications are added in the job log, and data from each object whose name matches the wildcard expressions are loaded into the database table.
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, etc. 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.
Wildcard expressions in an object name cannot be used when data is written to GCS after being exported from the database (or read from some other source).