How does encryption of data at rest work in GDPR compliance?

[Hernando]

Hello everyone, I'm assigned to implement GDPR compliance points into our partner's app and I'm finding it difficult to implement the encryption of data at rest, depending on the definition, it also describes that data at rest includes databases, but technically doing so will impact or make most of our systems unusable: For example, I cannot encrypt phone numbers, but I can make sure that the phone numbers contain no personal information (mostly because we don't store that kind of information) how does shopify will check those cases? Is there any documentation from shopify on which we can undertand what's the domain of these changes? I find the documentation incomplete and not accurate.

Thanks. 

Hernando