Data Warehouse Interview Questions and Answers
Question - 51 : - What is a Factless fact table?
Answer - 51 : -
Factless fact is a fact table without any value. Such a table only contains keys from different dimension tables.
Question - 52 : - What is a fact table?
Answer - 52 : -
A fact table contains the measurements, metrics, or facts of a business process. It is located at the middle of a star schema or a snowflake schema, and it is surrounded by dimension tables.
Question - 53 : - What is a conformed fact?
Answer - 53 : -
A conformed fact is a type of table that will be used across multiple data marts and multiple fact tables.
Question - 54 : - What is the core dimension?
Answer - 54 : -
The core dimension is a Dimension table, which is used, is dedicated for a single fact table or Data Mart.
Question - 55 : - What is dimensional data modelling?
Answer - 55 : -
Dimensional modeling is a set of guidelines to design database table structures for easier and faster data retrieval. It is a widely accepted technique. The benefits of using dimensional modeling are its simplicity and faster query performance. Dimension modeling elaborates logical and physical data models to further detail model data and data relationship requirements. Dimensional models map the aspects of every process within the business.
Dimensional Modelling is a core design concept used by many data warehouse designers to design data warehouses. During this design model, all the info is stored in two sorts of tables.
- Facts table
- Dimension table
The fact table contains the facts or measurements of the business, and the dimension table contains the context of measurements by which the facts are calculated. Dimension modeling is a method of designing a data warehouse.
Question - 56 : - What are the types of Dimensional Modelling?
Answer - 56 : -
Types of Dimensional Modelling are listed below:
- Conceptual Modelling
- Logical Modelling
- Physical Modelling
Question - 57 : - What is the difference between E-R modelling and Dimensional modelling?
Answer - 57 : -
The basic difference is that E-R modeling has a logical and physical model while Dimensional modeling has only a physical model. E-R modeling is required for normalizing the OLTP database design, whereas dimensional modeling is required for de-normalizing the ROLAP/MOLAP design.
Question - 58 : - What is a Dimension Table?
Answer - 58 : -
A dimension table is a type of table that contains attributes of measurements stored in fact tables. It contains hierarchies, categories, and logic that can be used to traverse nodes.
Question - 59 : - What is a degenerate dimension?
Answer - 59 : -
In a data warehouse, a degenerate dimension is a dimension key in the fact table that does not have its own dimension table. Degenerate dimensions commonly occur when the fact table’s grain is a single transaction (or transaction line).
Question - 60 : - What is the purpose of cluster analysis and data warehousing?
Answer - 60 : -
One of the purposes of cluster analysis is to achieve scalability so regardless of the quantity of data system will able to analyze its ability to deal with different kinds of attributes so no matter the data type of the attributes present in the data set able to deal with its discovery of clusters with attribute shape high dimensionality which have multiple dimensions more than 2d to be precise ability to deal with noise, so any inconsistencies in the data to deal with that and interpretability.