Algorithm: Date Shift (KBA7105)

Memory Requirements 

These algorithms have a very small memory footprint. 

Masked Value

The built-in algorithms only mask the Day part of the date (including dates with time). The year, month, hour, min, et cetera are left as is.  

Note:

To mask other parts of the date (or time) is easy. You can create a new algorithm using one of the OOTB Frameworks.

Date Formats 

A date format must be specified. This field appears when you select the DATE SHIFT algorithm from the Masking Algorithm dropdown list.

The default format is 'yyyy-MM-dd' and the list contains some common formats.

You can set the format to any format allowed in JAVA by navigation to the Rulset, editing the column specifying a date algorithm, and then selecting or entering the date format.  The information button next to the date format field provides more information on specifying date formats.

Examples of some common formats are (note single-quotes around text):

Tip: 'M' and 'd' for single-digit dates. 'MM' for '01, 02, ..., 12'.

yyyyMd
yyyyMMdd
yyyy-MM-dd
yyyy-MM-dd HH:mm:ss
yyyy-MM-dd'T'HH:mm:ss'Z'
yyyy-MM-dd'T'HH:mm:ss.SSS'Z'

Special characters and invalid date strings

Special characters and invalid date strings will be passed through unmasked. NULL and blank string will be passed through unmasked and all other cases will be marked as Nonconforming Data (and passed through). 

Casting to string

You may need to CAST a date to a STRING for unsupported datatypes. Look at the value and CAST as required and set Date Formats accordingly. 

For example, if a date is stored in an unsupported data type and the SELECT returns '20210626', then cast the value to a STRING and set the Date Format to 'yyyyMMdd'

Masking Examples

Below are examples of the three algorithms: Discrete, Fixed, and Variable. 

• ID reference number.
• Orig - The Original date.
• DS_Discrete - The masked value using Discrete. 
• DS_Fixed- The masked value using Fixed. 
• DS_Variable - The masked value using Variable. 

With date only (format: 'yyyy-MM-dd')
+----+------------+-------------+------------+-------------+
| id | orig       | DS_Discrete | DS_Fixed   | DS_Variable |
+----+------------+-------------+------------+-------------+
| 1  | NULL       | NULL        | NULL       | NULL        | << Passthrough values
| 2  |            |             |            |             |
+----+------------+-------------+------------+-------------+
| 3  | 1977-02-01 | 1977-02-06  | 1977-02-06 | 1977-02-03  | << Note: id 3 same as 4
| 4  | 1977-02-01 | 1977-02-06  | 1977-02-06 | 1977-02-10  |    Variable has different value.
+----+------------+-------------+------------+-------------+
| 3  | 1977-02-01 | 1977-02-06  | 1977-02-06 | 1977-02-10  | << Different year
| 5  | 1978-02-01 | 1978-02-20  | 1978-02-06 | 1978-02-04  |
+----+------------+-------------+------------+-------------+
| 3  | 1977-02-01 | 1977-02-06  | 1977-02-06 | 1977-02-10  | << Different month
| 6  | 1977-03-01 | 1977-03-13  | 1977-03-06 | 1977-03-06  |
+----+------------+-------------+------------+-------------+
| 3  | 1977-02-01 | 1977-02-06  | 1977-02-06 | 1977-02-10  | << Different day
| 7  | 1977-02-02 | 1977-02-06  | 1977-02-07 | 1977-02-12  |
+----+------------+-------------+------------+-------------+
| 8  | 1978-04-25 | 1978-04-06  | 1978-04-30 | 1978-04-01  | << Month rollover
| 9  | 1978-04-26 | 1978-04-06  | 1978-04-01 | 1978-04-28  |
| 10 | 1978-04-27 | 1978-04-06  | 1978-04-02 | 1978-04-01  |
| 11 | 1978-04-28 | 1978-04-06  | 1978-04-03 | 1978-04-29  |
| 12 | 1978-04-29 | 1978-04-06  | 1978-04-04 | 1978-04-07  |
| 13 | 1978-04-30 | 1978-04-06  | 1978-04-05 | 1978-04-07  |
| 14 | 1978-05-01 | 1978-05-24  | 1978-05-06 | 1978-05-03  |
| 15 | 1978-05-02 | 1978-05-24  | 1978-05-07 | 1978-05-06  |
+----+------------+-------------+------------+-------------+
Note: DateShift Fixed and Variable will never mask to the same as the input.


With date only (format: 'yyyy-M-d')

+----+------------+-------------+------------+-------------+
| id | orig       | DS_Discrete | DS_Fixed   | DS_Variable |
+----+------------+-------------+------------+-------------+
| 15 | 1978-05-02 | 1978-5-24   | 1978-5-7   | 1978-5-6    |
+----+------------+-------------+------------+-------------+
| 16 | 1978-12-1  | 1978-12-23  | 1978-12-6  | 1978-12-27  |
| 17 | 1978-5-12  | 1978-5-24   | 1978-5-7   | 1978-5-6    |
+----+------------+-------------+------------+-------------+


With time: (format: 'yyyy-MM-dd HH:mm')
+----+------------------+------------------+------------------+------------------+
| ID |       Orig       |    DS_Discrete   |      DS_Fixed    |   DS_Variable    |
+----+------------------+------------------+------------------+------------------+
| 1  | 1978-04-30 14:34 | 1978-04-06 14:34 | 1978-04-05 14:34 | 1978-04-08 14:34 |
+----+------------------+------------------+------------------+------------------+

Nonconforming Data Examples

Below are some examples of Nonconforming Data when masking a date.

Date format set to 'yyyy-MM-dd'.

+----+------------------+------------------+-----------------------+
| id | orig             | Nonconforming    | Comment               |
+----+------------------+------------------+-----------------------+
| 16 | 1978-12-1        | NNNNPNNPN        | Incorrect Date format |
| 17 | 1978-5-12        | NNNNPNPNN        | Incorrect Date format |
| 18 | 1978-04-02 14:34 | NNNNPNNPNNZNNPNN | Incorrect Date format |
| 19 | 1978-31-31       | NNNNPNNPNN       | Invalid date          |
| 20 | FOO BAR          | LLLZLLL          | Not a date            |
+----+------------------+------------------+-----------------------+

Related Articles

The following articles may provide more information or related information to this article:

• KBA: Algorithm: Summary (KBA4066)
• KBA: Algorithm Framework: Summary (KBA7880)