Reverse Engineering Legacy Data Systems with GenAI

May 29, 2025

Reverse Engineering Legacy Data Systems with GenAI

Fixing Slow Data Projects with Generative AI

One of the most paralyzing challenges in enterprise data engineering is working with systems that are mission-critical… but completely undocumented.

You’ve seen it before: a tangle of legacy SQL scripts, ETL workflows, or BI reports created by people who’ve long since left the company. The code still runs — but no one knows exactly how or why. Making changes feels risky. Migrating feels impossible.

At GenAI Protos, we call this problem “data archaeology.” And we’ve built Generative AI-based solutions to fix it.

The Problem: Undocumented Legacy Systems Slow Everything Down

Data teams often spend more time understanding existing logic than building anything new. This is especially true when:

  • Pipelines have grown organically for 10+ years 
  • There’s little to no documentation 
  • Original developers are no longer with the team 
  • There’s fear of “breaking something that still works” 

These conditions create a knowledge bottleneck:

  • Junior engineers can’t onboard quickly 
  • Modernization projects get delayed or blocked 
  • Code reviews and debugging become exhausting 
  • Business logic gets locked inside code no one understands 

Ultimately, your data strategy suffers because no one can move forward with confidence.

The Solution: GenAI-Powered Reverse Engineering

With LLM-powered analysis, we can now decode legacy systems at scale — not by brute force, but by understanding patterns, context, and logic.

At GenAI Protos, we use Generative AI to:

  • Read and interpret legacy code (SQL, ETL, shell scripts, etc.) 
  • Summarize what the logic does in plain English 
  • Extract key business rules and data transformation steps 
  • Identify dependencies and upstream/downstream flows 
  • Auto-generate flow diagrams or pseudo-code 

All of this happens at speed and scale — enabling teams to build structured understanding where there was only chaos.

Real-World Example

A large healthcare client had 700+ undocumented SQL jobs in a legacy data warehouse. Before they could migrate to Snowflake, they needed to understand:

  • What each job was doing 
  • How they were linked 
  • Which logic was still relevant 

Using our reverse engineering accelerator:

  • We explained over 85% of code in natural language 
  • Tagged business logic vs. technical logic 
  • Created lineage graphs to visualize data flow 
  • Auto-generated documentation for every script 

What would’ve taken 6–8 engineers several months to analyze was done in under 3 weeks.

Why This Works

  • Contextual Understanding: GenAI doesn’t just read code — it interprets intent, flow, and purpose.
  • Natural Language Summaries: Engineers and stakeholders get explanations they can actually understand.
  • Visual Flow Reconstruction: Automatically convert logic into process flows, perfect for modernization or QA.
  • Reusable Knowledge: Output can feed documentation, training guides, or migration roadmaps.

Who Benefits

  • Data Engineering Managers – Eliminate reliance on hard-to-find SMEs. 
  • Data Architects – Speed up discovery and impact analysis for platform modernization. 
  • Governance Teams – Gain visibility into legacy data logic for compliance or auditing. 
  • Business Analysts – Understand the “why” behind key data transformations. 

Final Takeaway

Reverse engineering doesn’t have to be a slow, manual, error-prone process. With GenAI Protos, you can transform legacy black boxes into clean, documented assets — ready for migration, enhancement, or automation.

Knowledge silos become shared insight. Unknowns become assets. And instead of spending weeks untangling old logic, your team can finally focus on building the future.