The Data Masking transformation maintains storage tables for repeatable substitution between sessions. A storage table row contains the source column and a masked value pair. Each time the Data Masking transformation masks a value with a repeatable substitute value, it searches the storage table by dictionary name, locale, column name, input value, and seed. If it finds a row, it returns the masked value from the storage table. If the Data Masking transformation does not find a row, it retrieves a row from the dictionary with a hash key.

The dictionary name format in the storage table is different for a flat file dictionary and a relational dictionary. A flat file dictionary name is identified by the file name. The relational dictionary name has the following syntax:

Informatica provides scripts that you can run to create a relational storage table. The scripts are in the following location:

The directory contains a script for Sybase, Microsoft SQL Server, IBM DB2, and Oracle databases. Each script is named Substitution_<database type>. You can create a table in a different database if you configure the SQL statements and the primary key constraints.

You need to encrypt storage tables for substitution masking when you have unencrypted data in the storage and use the same seed value and dictionary to encrypt the same columns.