What kind of data do you store in the gold layer of a data lake?

The gold layer is the final, production‑ready tier of a data lake. It contains data that has been fully curated, cleansed, and enriched so that downstream consumers can use it without additional processing. Typical contents include: 1) Aggregated metrics (daily sales, monthly churn) that are pre‑computed for reporting; 2) Joined and denormalized tables that combine multiple source systems into a single, business‑centric view; 3) Enriched data with calculated fields, derived attributes, and business rules applied; 4) Data that has passed quality checks, with nulls handled, outliers flagged, and schema validated; 5) Data that is partitioned and compressed (Parquet/ORC) for efficient query performance; 6) Versioned snapshots that support time‑travel queries. The gold layer is often stored in a columnar format on a distributed file system (S3, ADLS) and registered in a catalog (AWS Glue, Hive Metastore). It serves analytics teams, BI dashboards, and ML pipelines that require consistent, trustworthy data. By keeping raw (bronze) and curated (silver) layers separate, the gold layer provides a single source of truth that reduces duplication and ensures compliance with governance policies.