What is dimension table and how it is related to fact table?
Dimension table Dimension table is a table which contain attributes of measurements stored in fact tables. This table consists of hierarchies, categories and logic that can be used to traverse in nodes. Fact table contains the measurement of business processes, and it contains foreign keys for the dimension tables.
Can a single dimension appear several times in the same fact table?
A single physical dimension can be referenced multiple times in a fact table, with each reference linking to a logically distinct role for the dimension. For instance, a fact table can have several dates, each of which is represented by a foreign key to the date dimension.
Why do we need dimension table?
Dimension tables describe the different aspects of a business process. For example, if you are looking to determine the sales targets, you can store the attributes of the sales targets in a dimension table. Dimension tables group the data in the database when the business creates reports.
Why does the dimension table not normalize the fact table?
Normalization: Dimension table is not normalized because normalization splits the data and creates additional tables which decrease the efficiency of the query execution as it must pass through these additional tables when it wants to recover measurements from the fact table for any corresponding attribute in the dimension table.
What are the characteristics of a fact table?
Below are the characteristics of the fact table: Keys: It has a key or a primary key which is the accumulation of all the primary keys of all dimension tables linked with it. That key is known as a concatenated key that helps to uniquely identify the row.
How are fact tables used in data warehouse?
These tables hold fields that represent the direct facts, as well as the foreign fields that are used to connect the fact table with other dimension tables in the Data Warehouse system. A Data Warehouse system can have one or more fact tables, depending on the model type used to design the Data Warehouse.
Which is a foreign key in the fact table?
It has a primary key for each dimension which is acts as a foreign key in the dimension table. It has a foreign key associated with the primary key of the fact table. It stores the filter domain and reports labels in dimension tables. It stores the detailed atomic data into dimensional structures.