# Medallion Gold-Layer & IaC Standardization

Suhas Narayan | Business Intelligence Engineer

Sanitized portfolio case study prepared for portfolio review.

## Business challenge

The team was moving from ad hoc dashboard SQL to code-managed data products. Inconsistent development practices, recurring design debates, and unclear validation requirements made changes harder to review and extend safely.

## My contribution

I identified recurring gaps, authored four standards, and drove peer and stakeholder reviews covering development, customer access, reporting design, and dataset changes. I worked with data engineers on testing guidance and secured customer agreement on the approach for retiring legacy reporting fields.

## Decisions & methods

- Protected dataset grain as models evolved. Established explicit primary keys and rules for preserving upstream grain. Required separate datasets when measures needed different levels of detail, preventing enhancements from silently changing row meaning.
- Separated shared definitions from interactive calculations. Placed reusable business rules in code while keeping filter-dependent aggregations and rates in dashboards where they could recalculate correctly for the selected population.
- Turned validation into a repeatable release practice. Defined schema, uniqueness, row-count, and downstream metric checks, with before-and-after evidence required during review. Documented setup, testing, deployment verification, and troubleshooting.
- Established a controlled path for access and schema changes. Standardized viewer access from user acceptance testing through launch and secured agreement on replacement datasets for retiring legacy columns.

## Outcome

All five engineers adopted the development standards, and three BIEs onboarded using the guide. Following adoption, first-revision merges increased from 60% to 71%, while average revisions declined from 1.58 to 1.44, approximately 9%.

## Results & context

The review analysis covered 403 shipped code reviews from seven authors. The standards supported an existing Gold reporting layer containing 23 tables and 51.3 million rows. Development and access standards were adopted; the reporting-design strategy had completed review and was in user acceptance testing.

## Methods & Tools

Medallion architecture, Gold-layer modeling, Data contracts, AWS Glue, AWS CDK / IaC, CI/CD, Engineering enablement