Data masking as we all know is a data protection layer which replaces/scrambles/masks sensitive data being disclosed to unwanted/unauthorized users. “Static Data Masking” also known as Persistent data masking is a method to protect data at rest. It is a new security feature released in SQL 2019 (available for public preview at the time this blog was written) that helps users create a copy of masked [sensitive] data from production environment. Using this feature, copy of the live data is crated with appropriate masking functions; and the masked copy can be shared with users who intend to work on non-live data. This feature also helps keep organizations compliant which are subject to data protection/privacy regulations such as GDPR.
Data masking process starts with users configuring masking operations for the columns in database which contain sensitive information. Data is copied to a new database during the data copy process from the live system and then masking functions (according to the masking configuration) are applied to mask the data at column level. Unlike dynamic data masking, static data masking is persisted and irreversible (one-way process), original data cannot be retrieved.
Static data masking can be used for development, testing, analytics and business reporting, compliance, troubleshooting, and any other scenario where specific data cannot be copied to different environments.
References:
SQLpathy 