A MERGE pipeline keys dim_customer on email

A medium Pipeline Design interview practice problem on DataDriven. Write and execute real pipeline design code with instant grading.

Domain

Pipeline Design

Difficulty

medium

Problem

A MERGE pipeline keys dim_customer on email. A customer updated their email, the MERGE missed the match, and a duplicate row was inserted; historical lineage broke because the natural key changed. The section frames the fix in two halves: a stable surrogate key and a uniqueness assertion at write time. Apply both halves on the canvas; warehouses do not enforce primary keys for you.

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