Propagate

Goal

Use propagate to anonymize values of a table column, and then do the same anonymization on the same values in other table columns. Useful for preserving foreign key constraints, and to ensure data integrity after anonymization is complete.

Use cases for propagate

Use propagate when

• There is a foreign key constraint(s) to the column you are anonymizing
• when columns in different tables must be anonymized the same, even though there does not exist a foreign key constraint
  • Without the foreign key constraint, you can ensure both tables are fully anonymized by
    • First update the one table and propagate the update to the other table
    • Then update the other table with a where clause, so the updates are only performed on the subset of values that were not updated by the propagate

propagate is only usable in update Work Tasks.

Ano Structure and Examples

Structure

    update <parent-table>
        mask ID
            format %d
            unique
            sequence -1 1
            temporary-value 999999
            propagate <child-table-1>.<foreign-key-column>, <child-table-2>.<foreign-key-column>

Foreign Key Example

table Customer
    column integer customerNo
    primary-key customerNo
    ...
table Address
    column integer ID size 10
    column integer customer_customerNo
    column ...
    primary-key ID
...
foreign-key
    Customer customerNo
    Address customer_customerNo
...
task <task-name> {
    // Update primary key and propagate to the foreign key
    update Customer
        mask customerNo
            format %d
            unique
            sequence 1000 1
            temporary-value 999999
            propagate Address.customer_customerNo
}

Foreign Key Example

Note that Address has a foreign key constraint to Customer, so every Address.customer_customerNo value must exist in Customer.customerNo

• We update customerNo in parent table Customer and propagate the update to child table Address.

No Foreign Key Example

table Customer
    column integer customerNo
    primary-key customerNo
    ...
table Address
    column integer ID size 10
    column integer customer_customerNo
    column ...
    primary-key ID
...
task <task-name> {
    update Customer
        mask customerNo
            format %d
            unique
            sequence 1000 1
            temporary-value 999999
            propagate Address.customer_customerNo

    update Address
        where "Address.customer_customerNo NOT IN (SELECT DISTINCT Customer.customerNo FROM Customer)"
        mask customer_customerNo
            format %d
            unique
            sequence 100 1
            temporary-value 999999
}

No Foreign Key Example

There is no foreign key constraint on Address to Customer. This means values of Address.customer_customerNo may or may not exist in Customer.customerNo.

• When they exist, then update the values through propagate
• When they do not exist, then update the values separately, using a where clause. The where clause allows us to only update values in Address not hit by the propagate from Customer

Two Foreign Keys Example

table Customer
    column integer customerNo
    primary-key customerNo
    ...
table Address
    column integer ID size 10
    column integer customer_customerNo
    column ...
table Booking
    column integer id
    column integer customer_customerNo
    column ...
...
foreign-key
    Customer customerNo
    Booking customer_customerNo
foreign-key
    Customer customerNo
    Address customer_customerNo

task <task-name> {
    update Customer
        mask customerNo
            format %d
            unique
            sequence 1000 1
            temporary-value 999999
            propagate Address.customer_customerNo, Booking.customer_customerNo
}

Two Foreign Keys Example

Both Booking and Address have foreign key constraints to Customer

• When updating customerNo in Customer, then propagate customer_customerNo to both Booking and Address.