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Slowly changing dimension (SCD)

A slowly changing dimension is a descriptive attribute, like a customer segment, whose value changes over time and needs history tracked.

Written by Reflective Data experts · updated Oct 5, 2026

Type 1 overwrites the old value, losing history. Type 2 adds a new row for each change with valid-from and valid-to dates, so you can report what was true at any point in time.

dbt snapshots are a common way to implement type 2 history.

related

dbt snapshotDimensionStar schema

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