Masking type is a method to change column data that is returned from queries. Specify the masking type in the function_type parameter. The following masking types can be specified and selected depending on the masking target data type.
Full masking
All the data in the specified column is changed. The changed value returned to the application that made the query varies depending on the column data type.
For example, 0 is used for a numeric type column and a space is used for a character type column.
Partial masking
The data in the specified column is partially changed.
For example, digits except the last four digits of an employee number can be changed to "*".
Regular expression masking
The data in the specified column is changed via a search that uses a regular expression.
For example, for strings such as email address that can have variable length, "*" can be used to change characters preceding "@" by using a regular expression. Regular expression masking can only be used for character type data.
Note
If multiple valid masking targets are specified for a function, the masking type for the left-most masking target will be applied.
For example, if "SELECT GREATEST(c1, c2) FROM t1" is executed for numeric type masking target c1 and c2, the masking type for c1 will be applied.
When masking the data that includes multibyte characters, do not specify partial masking for masking type. The result may not be as expected.
