40 Minutes to Reverse-Engineer a Legacy Data Warehouse (Including the Ghost Artifacts Nobody Knew Existed)

‍

TL;DR: Genesis agents reverse-engineered a full Oracle EDW connected to SAP, PeopleSoft, Siebel, and flat files in 40 minutes. They cataloged 69 tables, decoded 14 Informatica mappings, flagged critical data quality issues, designed a Snowflake target architecture, and delivered an executive migration assessment. What consultants spend months surfacing, Genesis found in one sitting.

‍

Discovery Is Where Migrations Die

Before any data warehouse migration starts, someone has to document what's actually in the system. That means reverse-engineering ETL logic, tracing dependencies, and profiling data quality across years of accumulated changes.

Gartner reports that nearly 60% of data warehouse migrations exceed planned timelines due to poor data profiling and weak governance. Discovery is almost always the culprit, and 80% of data migration projects run over time or budget due to missing strategy and unreliable processes.

The problem isn't effort. Legacy systems accumulate years of undocumented changes, and reconstructing that context manually takes months. It's the same reason knowing what connects to what across your data stack is a prerequisite for any serious migration, not an afterthought.

‍

What Genesis Did in 40 Minutes

Genesis agents were pointed at a legacy Oracle EDW with four OLTP source systems (SAP, PeopleSoft, Siebel, flat files), 14 Informatica PowerCenter mappings, and 69 database tables.

‍

This is the same class of work Genesis agents applied when turning raw claims data into a live analytics dashboard in 7 minutes: define the environment, surface the problems, build the outputs.

‍

The Ghost Artifacts Nobody Knew Were There

The most valuable output wasn't the architecture. It was what was hiding in the existing system:

• An employee hired in 2023 who was listed as terminated in 2019
• A phantom customer with $2.1M in open sales orders and no master record
• A GL account off by $1,234.56
• Credit limits stored as TEXT, causing silent comparison failures
• 15 ghost artifacts: dead tables, abandoned test data, and an empty ODS layer running for years doing nothing

These issues exist in nearly every long-running legacy EDW. Thorough assessment prevents the surprises that turn six-month migrations into eighteen-month ordeals Airbyte, but thorough assessment has always required expensive specialist time. According to Airbyte's cloud data warehouse migration planning guide, most teams underestimate this phase until it derails the project.

‍

What the Assessment Delivered

Along with the data quality findings, Genesis produced a full operational assessment including a risk heat map, per-mapping readiness scores, end-to-end lineage diagrams, and a prioritized remediation list with five items flagged for resolution before production cutover. The same agents that flagged them will resolve them.

Migration projects extending beyond 12 months often see cost inflations of 30% or more. Data Stack Hub As OvalEdge outlines in their complete guide to data warehouse migration, compressing the discovery and assessment phase is one of the highest-leverage moves a migration team can make. Genesis does it in a single session.

Frequently Asked Questions

What is a legacy EDW discovery process? The phase where teams catalog tables, trace ETL logic, and document every integration before migration begins. In traditional projects, this takes weeks or months.

What is Snowflake Bronze/Silver/Gold architecture? A layered data design where Bronze holds raw data, Silver holds cleaned data, and Gold holds business-ready aggregates for reporting.

What does 84.5% migration readiness mean? The environment is largely ready to migrate, with five specific issues flagged for resolution before production cutover.

What are ghost artifacts? Inactive tables, orphaned objects, test data residue, and empty process layers left running in a system long after their original purpose ended.