What is data duplication during extraction?

< 1 min read

Data duplication during extraction happens when the same records are pulled multiple times from the source system into the target dataset.
It usually occurs due to incorrect incremental logic or missing unique keys.
In one ETL validation, daily orders were duplicated because extraction used order_date instead of last_updated_timestamp.
So updated orders were reloaded every day.
I identified it when total revenue suddenly doubled in the dashboard.
We fixed it by using primary key + last modified date and applying deduplication logic.
This is important because duplicates impact KPIs like sales, customers, and conversion rate.
As a BA, I validate record counts and totals after each load to catch it early.

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