Why use OLAP?
- Queries run 1000% faster
- Click to query
- Near real-time information
- Reduce stress on your OLTP system
Two kinds of tables form a data warehouse:
- Also called measures.
- The fact table is the table that holds the facts of the business that need to be analysed, such as sales, profits, amount of storage at hand, etc.
- This type of data is often numeric.
- The values are quite often subject to aggregation (pre-calculating roll-ups of data over hierarchies, which subsequently yield improved query results).
- Building the fact table is an important step towards building your data warehouse.
- A dimension is a collection of properties along which we conduct our analysis of the facts.
- Dimensions allow us to view the fact in different contexts.
- Common dimensions used in sales -related data marts include:
- Scenarios such as actual, budgeted, or estimated numbers
- Star Schemas unite dimensions and facts
- De-normalized schemas (deliberately duplicate data for fast query result, so no need to join tables)