Updating olap dimensions
Commercial OLAP systems usually treat OLAP dimensions as static entities.
In data warehousing, a dimension is a collection of reference information about a measurable event.
If performance is too slow, there is a third option called HOLAP (Hybrid OLAP), which stores the data in the relational database but the aggregations in the OLAP database.
When the source data is updated the aggregations will be processed again.
This offers zero latency, and relatively decent performance when the queries are resolved from the aggregations, but slow performance when the users drill down or the query has to access the relational store.