Worked on maintaining the reliability of the column_values_unique metric provider in the great_expectations/great_expectations repository, focusing on compatibility across SQLAlchemy versions. Addressed a runtime regression by updating type checks for SQLAlchemy’s Select class, specifically restoring support for SQLAlchemy 1.4. Used Python and SQLAlchemy to ensure that data validation processes remained stable for users on older versions, minimizing the risk of runtime errors. Validated the solution through continuous integration and collaborative code review, emphasizing backend development best practices. The work prioritized cross-version stability, ensuring that data quality checks continued to function as expected without introducing breaking changes for existing users.