What is a primary key and why is it important for data extraction?

< 1 min read

A primary key is a field or set of fields that uniquely identifies each record in a table.
It ensures every row can be tracked without ambiguity.
During data extraction, it helps identify new, updated, or deleted records correctly.
In my project, we used invoice_id as the primary key for incremental loads.
This prevented duplicate data when running daily ETL jobs.
Primary keys make joins between source tables accurate and predictable.
They also support data validation and reconciliation with source systems.
Without a primary key, extraction logic becomes complex and error-prone.

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