What are dimensions in a database?
A database dimension is a collection of related objects, called attributes, which can be used to provide information about fact data in one or more cubes. For example, typical attributes in a product dimension might be product name, product category, product line, product size, and product price.
What are dimensions in datawarehouse?
In data warehousing, a dimension is a collection of reference information about a measurable event. In this context, events are known as “facts.” Dimensions categorize and describe data warehouse facts and measures in ways that support meaningful answers to business questions.
What is a dimension table in a database?
A dimension table is a table in a star schema of a data warehouse. A dimension table stores attributes, or dimensions, that describe the objects in a fact table. A data warehouse organizes descriptive attributes as columns in dimension tables.
What are facts and dimensions in database?
The fact table mainly consists of business facts and foreign keys that refer to primary keys in the dimension tables. A dimension table consists mainly of descriptive attributes that are textual fields. A dimension table contains a surrogate key, natural key, and a set of attributes.
What is a dimension in a data set?
A dimension is a structure that categorizes facts and measures in order to enable users to answer business questions. In a data warehouse, dimensions provide structured labeling information to otherwise unordered numeric measures. The dimension is a data set composed of individual, non-overlapping data elements.
What is a dimension in SQL?
All Microsoft SQL Server Analysis Services dimensions are groups of attributes based on columns from tables or views in a data source view. Dimensions exist independent of a cube, can be used in multiple cubes, can be used multiple times in a single cube, and can be linked between Analysis Services instances.
What are dimensions and facts in SQL?
A fact table works with dimension tables. A fact table holds the data to be analyzed, and a dimension table stores data about the ways in which the data in the fact table can be analyzed. Thus, the fact table consists of two types of columns.
What do you call an instance of a database dimension?
Cubes contain all the dimensions on which users base their analyses of fact data. An instance of a database dimension in a cube is called a cube dimension and relates to one or more measure groups in the cube. A database dimension can be used multiple times in a cube.
How is a database dimension used in a cube?
A database dimension can be used multiple times in a cube. For example, a fact table can have multiple time-related facts, and a separate cube dimension can be defined to assist in analyzing each time-related fact.
How is a multidimensional database different from a relational database?
Multidimensional data is easier to recognize when it is presented as an array rather than a relational database. In the previous two-dimensional database example, it is easy to see that there are two dimensions (item and store), and that each dimension contains two positions.
Why do we need date dimensions in fact tables?
Since many fact tables in a data warehouse are time series of observations, one or more date dimensions are often needed. One of the reasons to have date dimensions is to place calendar knowledge in the data warehouse instead of hard-coded in an application.