Business Intelligence Basics
BI Concept: Star Schema: The star schema has a center, represented by a fact table, and the points of the star, represented by the dimension tables. Snowflake Schema: In a snowflake, the dimension tables are normalized. ODS: ODS should be considered only when information retrieval requirements are to be real time and cannot access OLTP systems because of criticality of resources. Dimension Types: Changing Dimension: Changing dimension is the dimension which has at least one attribute whose value would change over the time. Slowly Changing Dimensions: Attributes of a dimension that would undergo changes over time. For example: Employee work location • Type I: The existing record is updated with change. • Type II: History is preserved, a new record is added to dimension and old record is marked as inactive. EndDate or IsLatest is generally used to represent latest record of a business key. • Type III: Type III preserve...