1. MIS 451 Building Business Intelligence Systems Logical Design (5) – Aggregate

2. 2 F4: Aggregate In data warehouse design, we choose the gain of fact table to be the possible lowest level. Grain: orderline

3. 3 F4: Aggregate To choose the lowest level of fact: is not because analysts want to query on single record is because analysts want to flexibly cut and group records.

4. 4 F4: Aggregate However, keep the most detailed fact records could result in huge-size fact table: TeraBytes slow query

5. 5 F4: Aggregate To keep flexibility of data warehouse, fact tables which store facts in their lowest level need to be kept. To improve query performance, another type of fact table which stores precomputed summaries of detailed facts is required. (Logical solution)

6. 6 F4: Aggregate Aggregate fact table is a fact table that summarize base-level fact table records along one or several dimensions. Aggregate dimension tables is a dimension table that summarize base-level dimension table records.

7. 7 F4: Aggregate Marketing managers check daily product sales by city --- aggregate by city in customer dimension

8. 8 F4: Aggregate Aggregate fact table Aggregate dimension table

9. 9 F4: Aggregate

10. 10 Readings: Chapter 13: p187 – p197