Qrlew: Rewriting SQL into Differentially Private SQL
This addresses the challenge for data practitioners and owners in applying differential privacy to SQL queries without technical integration, though it is incremental in automating existing rewriting methods.
The paper tackles the problem of enabling differential privacy for SQL queries by introducing Qrlew, a library that rewrites SQL into differentially private SQL, allowing execution in standard data stores with strong privacy guarantees.
This paper introduces Qrlew, an open source library that can parse SQL queries into Relations -- an intermediate representation -- that keeps track of rich data types, value ranges, and row ownership; so that they can easily be rewritten into differentially-private equivalent and turned back into SQL queries for execution in a variety of standard data stores. With Qrlew, a data practitioner can express their data queries in standard SQL; the data owner can run the rewritten query without any technical integration and with strong privacy guarantees on the output; and the query rewriting can be operated by a privacy-expert who must be trusted by the owner, but may belong to a separate organization.