Shrunken Changing Dimension

Shrunken Rollup Changing Dimension

Lesson Notes

Shrunken Rollup Changing Dimension Lesson Notes:

  1. Presentation Mode
  2. Static Mode

Video

Shrunken Rollup Dimensions

  • Shrunken Rollup dimension is used for developing aggregate (higher level of summary) fact tables.

  • It required that the data model has a lower level of granularity.

    • We have a daily usage fact table, and we need to have a higher level of monthly usage. So, we use the monthly dimension to get a summary of the daily.

    • We have a daily usage fact table aggregated on area-id, and we need to create another summary table aggregated based on city id. So, the new grain level here is the new dimension for the city.

Shrunken Rollup Dimensions Cont.

In this example we use the AreaId and the relation with CityID for shrunken the dimension and do higher level of aggregations.

  • Order detail per AreaID
    OrderDateAreaIDTotalOrders
    12345678912320
    12345678912330
    12345678967810
    12345678967812
  • City and Area relationship dimension
    AreaIDAreaNameCityID
    123Al-Matareya1
    678Ain shams1
  • City dimension
    CityIDCityName
    1Cairo
  • Order detail per CityID
    OrderDateCityIDTotalOrders
    123456789172