Answer Posted / manoj
When developing a dimensional model, we often encounter miscellaneous flags and indicators. These flags do not logically belong to the core dimension tables.
A junk dimension is grouping of low cardinality flags and indicators. This junk dimension helps in avoiding cluttered design of data warehouse. Provides an easy way to access the dimensions from a single point of entry and improves the performance of sql queries.
Example: For example, assume that there are two dimension tables (gender and marital status). The data of these two tables are shown below:
Code:
Table: Gender
Id Gender_status
----------------
1 Male
2 Female
Table: Marital Status
Id Marital_Status
----------------
1 Single
2 Married
Here both the dimensions have low cardinality flags. This will cause maintenance of two tables and decrease performance of sql queries.
We can combine these two dimensions into a single table by cross joining and can maintain a single dimension table. The result of cross join is shown below:
Code:
id gender mrg_status
--------------------
1 Male Single
2 Male Married
3 Female Single
4 Female Married
This new dimension table is called a junk dimension. This will improve the manageability and improves the sql queries performance.
Is This Answer Correct ? | 12 Yes | 0 No |
Post New Answer View All Answers
Do you always need to copy the data before reporting on it?(Example, real-time & on-demand reporting is a requirement)?
What is the use of incremental aggregation? Explain me in brief with an example?
Where do we use semi and non additive facts?
What are the stages that are required in data warehousing?
Explain what is a staging area? Do we need it? What is the purpose of a staging area?
What needs to be done when the database is shutdown?
What is the function of surrogate key in data warehousing?
What is the difference between power center & power mart?
Explain the difference between data ware house & data mart?
What is the difference between er modeling and dimensional modeling?
What is the working process for application.cfm?
explain about balanced dimension,
Explain what is difference between query studio and report studio?
What is the difference between power center and power mart?
What is cubes?