Understanding Bronze, Silver, and Gold Layers in Databricks
The Bronze, Silver, and Gold layers in Databricks are part of the Medallion architecture, a data design pattern used to organize data logically and incrementally improve its quality. This architecture is crucial for managing data effectively, ensuring it is reliable and suitable for business intelligence and machine learning applications.
Bronze Layer
The Bronze layer is where raw, unvalidated data is ingested from external sources. It maintains the original format of the data and is intended for consumption by workloads that enrich data for the Silver layer. Minimal validation is performed here, and it serves as a single source of truth, preserving data fidelity and enabling auditing by retaining historical data.
Silver Layer
The Silver layer involves data cleaning and validation. It enhances data quality by correcting errors and inconsistencies, performing schema enforcement, handling null values, deduplicating data, and resolving late-arriving data issues. This layer structures data into a more consumable format for downstream processing and is suitable for data analysts and scientists.
Gold Layer
The Gold layer is designed for business users and contains refined and aggregated data. It is optimized for analytics and reporting, implementing business logic and rules to meet organizational needs. Data in this layer is typically stored in data marts, which are subsets of data warehouses focused on specific business sectors.
Frequently Asked Questions
- Q: What is the primary purpose of the Medallion architecture?
A: The primary purpose is to incrementally improve data quality and reliability by organizing data into logical layers, making it suitable for business intelligence and machine learning applications.
- Q: Can data be written directly to the Silver layer from ingestion?
A: No, Databricks does not recommend writing directly to the Silver layer from ingestion due to potential schema changes or corrupt records, which could introduce failures.
- Q: Who are the intended users of the Gold layer?
A: The Gold layer is intended for business analysts, BI developers, data scientists, machine learning engineers, executives, and operational teams.
- Q: What data types are recommended for storing fields in the Bronze layer?
A: Fields in the Bronze layer are recommended to be stored as strings, VARIANT, or binary to protect against unexpected schema changes.
- Q: How does the Silver layer handle data quality?
A: The Silver layer enhances data quality by performing operations such as schema enforcement, handling null values, data deduplication, and data quality checks.
- Q: Can the Bronze layer handle both streaming and batch transactions?
A: Yes, the Bronze layer can handle both streaming and batch transactions from various sources, including cloud storage and message buses.
- Q: What is the role of metadata in the Bronze layer?
A: Metadata in the Bronze layer, such as provenance or source of the data, helps in auditing and tracking the origin of the data.
Bottom Line
The Bronze, Silver, and Gold layers in Databricks’ Medallion architecture provide a structured approach to data management, ensuring data quality and reliability. This multi-layered approach is crucial for organizations seeking to leverage their data for informed decision-making and efficient analytics.