Summary
In this chapter we turned our attention to airline trips or routes; we briefly touched on similar scenarios drawn from the shipping and travel services industries. We examined the situation in which we have multiple fact tables at multiple granularities with multiple grain-specific facts. We also discussed the possibility of combining dimensions into a single dimension table for cases in which the row count volumes are extremely small or when there are additional attributes that depend on the combined dimensions. Again, combining correlated dimensions should be viewed as the exception rather than the rule.
We wrapped up this chapter by discussing several date and time dimension techniques, including country-specific calendar outriggers and the handling of absolute and relative dates and times.