Tag
slowly-changing-dimensions
- Jun 11, 2026 Orphan Keys: Checking Referential Integrity Without Foreign Keys Warehouses rarely enforce foreign keys, so referential integrity becomes a scheduled anti-join; its cost, its two directions, and the time dimension that makes it ambiguous. data engineering
- Jun 10, 2026 Choosing Between SCD Types 1, 2, 3 and 6 The cost of overwriting an attribute, the cost of versioning it, and the cost of keeping a previous value in a column, set against the questions each type can and cannot answer. data engineering
- Apr 7, 2026 Late-Arriving Dimensions and Inferred Members What happens when a fact references an entity the dimension has never seen, how inferred rows let the fact load proceed, and why the placeholder key is a debt with an interest rate. data engineering
- Apr 13, 2024 Type 2 Slowly Changing Dimensions: Versions, Validity and Lookups How a dimension row is versioned with surrogate keys and effective dates, why the load-time lookup is the hard part, and how facts join to the version that was current when they occurred. data engineering
- Sep 14, 2023 Bitemporal Dimension History: Effective Time and Assertion Time Why a single validity interval cannot express both when an attribute was true and when the warehouse believed it, and what two intervals cost in keys, joins and corrections. data engineering