Sorting and Filter Over PII Data

I have a large set of User PII data, currently, we are storing on Relational Data encrypted with AWS KMS. Now I have to paginate data based on UserName. The only we have to do right now is load all decrypted data on memory or cache and then do the sorting and pagination.

Please suggest any approach, Tool, or framework which supports sorting on PII masked data. Services are using Java as language.