In reading order.
KC Star V2 leaked aggregate rows because base facts and rollups shared one table. V3 gives aggregates a dedicated SalesAggregationFact table with its own SCD2 - and the fix is as much about what SalesFact loses as what the new table gains.
An average with no denominator is a number you can't defend. KC Star V3 adds a FactCount column to every aggregate - how many facts went into this rollup - turning each stored aggregate into something you can audit rather than just trust.
V3's rewritten CreateAggregatedFacts expires every aggregate and rebuilds them all from scratch on each run. It is blunt, it is correct, and the trade between rebuild-it-all simplicity and incremental cleverness is one KC Star kept relitigating all the way to V8.
V3 ships the largest usage-example set of the early versions - twenty queries against base facts and aggregates living in two tables. A tour of what a dual-star warehouse lets you ask, from base-vs-aggregate joins to watching a rollup evolve over time.
