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DP-750 · 3.1.6 · Prepare and process data

Choose SCD type

Choose a slowly changing dimension (SCD) type

Use SCD Type 1 for current state only and Type 2 when historical versions of changing dimension records must be preserved.

See the source change first

Microsoft Learn example showing one changed source row becoming a CDC update record with an operation and sequence number.

Once a change arrives, the model decides whether to overwrite the current row or preserve history.

Type 1 or Type 2

  • SCD Type 1

    History
    No
    Change
    Overwrite row
    Best fit
    Current state
    Cost
    Lower

  • SCD Type 2

    History
    Yes
    Change
    Add new version
    Best fit
    Point-in-time analysis
    Cost
    More rows and storage
Slowly changing dimensions

Type 1 keeps only the latest value. Type 2 preserves historical versions with validity information.

Choose from the business question

If consumers only need the current customer address or category, Type 1 is simpler. Use Type 2 when reports must reconstruct what was true at a past business date.

Key points

  • Type 1: Overwrites prior attribute values
  • Type 2: Preserves historical versions
  • History tracking: Adds temporal versions for changes
  • Requirement: Choose based on whether past states matter

Exam trap

Do not enable Type 2 history if consumers only need current state and history adds no value.

Sources · 1 Microsoft Learn page Show ▾

Checked on October 4, 2026. Report a problem

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