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Sandeep
Sandeep

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Day 17: Building a Real ETL Pipeline in Spark Using Bronze–Silver–Gold Architecture

Welcome to Day 17 of the Spark Mastery Series.
Today you build what most data engineers actually do in production — a layered ETL pipeline using Spark and Delta Lake.

This architecture is used by:

  • Databricks Lakehouse
  • Modern GCP/AWS data platforms
  • Streaming + batch pipelines

Let’s build it step by step.

🌟 Why Bronze–Silver–Gold?

Without layers:

  • Debugging is hard
  • Data quality issues propagate
  • Reprocessing is painful

With layers:

  • Each layer has one responsibility
  • Failures are isolated
  • Pipelines are maintainable

🌟 Bronze Layer — Raw Data

Purpose:

  • Store raw data exactly as received
  • No transformations
  • Append-only

This gives: ✔ Auditability
✔ Replayability

🌟 Silver Layer — Clean & Conformed Data

Purpose:

  • Deduplicate
  • Enforce schema
  • Apply business rules

This is where data quality lives.

🌟 *Gold Layer — Business Metrics
*

Purpose:

  • Aggregated metrics
  • KPIs
  • Fact & dimension tables

Used by:

  • BI tools
  • Dashboards
  • ML features

🌟 Real Retail Example

Bronze:
order_id, customer_id, amount, updated_at

Silver:

  • Latest record per order_id
  • Remove negative amounts

Gold:

  • Daily revenue
  • Total orders per day

🌟 Why Delta Lake is Perfect Here

Delta provides:

  • ACID writes
  • MERGE for incremental loads
  • Time travel for debugging
  • Schema evolution
  • Perfect for layered ETL.

🚀 Summary

We learned:

  • Bronze–Silver–Gold architecture
  • End-to-end ETL with Spark
  • Deduplication using window functions
  • Business aggregation logic
  • Production best practices

Follow for more such content. Let me know if I missed anything. Thank you!!

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