What is factless fact table in data warehouse?
A factless fact table is a fact table that does not have any measures. It is essentially an intersection of dimensions. On the surface, a factless fact table does not make sense, since a fact table is, after all, about facts. Factless fact tables offer the most flexibility in data warehouse design.
What does a fact table contains?
Fact tables contain the content of the data warehouse and store different types of measures like additive, non additive, and semi additive measures. Fact tables provide the (usually) additive values that act as independent variables by which dimensional attributes are analyzed.
What is fact table and Factless table?
A factless fact table is a fact table that does not have any measures. It is essentially an intersection of dimensions (it contains nothing but dimensional keys). There are two types of factless tables: One is for capturing an event, and one is for describing conditions.
What is aggregate fact tables in data warehouse?
Aggregate fact tables are special fact tables in a data warehouse that contain new metrics derived from one or more aggregate functions (AVERAGE, COUNT, MIN, MAX, etc..) or from other specialized functions that output totals derived from a grouping of the base data.
What are factless fact tables used for?
Factless fact tables are only used to establish relationships between elements of different dimensions. And are also useful for describing events and coverage, meaning tables contain information that nothing has happened. It often represents many-to-many relationships. The only thing they have is an abbreviated key.
What are Factless facts in Microstrategy?
A factless fact table is table that doesn’t have fact at all. They may consist of nothing but keys. There are tow types of factless fact table.
What is factless fact table why we need it?
In conclusion, factless fact tables are important dimensional data structures use to convey transactional information which contain no measures. These tables are occasionally necessary for capturing important dimensional relationships which are critical to the meeting the defined business reporting requirements.
How do you create a fact table in SQL?
Use the wizard to create the corresponding fact and dimension tables.
- In Data Modeler, lock the model for editing.
- In the Database menu in the left pane, right-click the source table that contains the fact and dimensional data that you want to model, select Add to Model, and then select Add as Fact and Dimension Tables.
What is a factless fact and when would you use it give examples?
They are often used to record events or coverage information. Common examples of factless fact tables include: Identifying product promotion events (to determine promoted products that didn’t sell) Tracking student attendance or registration events.
What is rollup fact table?
Aggregate fact tables are simple numeric rollups of atomic fact table data built solely to accelerate query performance. These aggregate fact tables should be available to the BI layer at the same time as the atomic fact tables so that BI tools smoothly choose the appropriate aggregate level at query time.
What is the meaning of Factless?
Filters. Lacking facts; inaccurate or fictional.
Why a factless fact table is used?
Factless fact tables are only used to establish relationships between elements of different dimensions. And are also useful for describing events and coverage, meaning tables contain information that nothing has happened. It often represents many-to-many relationships.