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Data warehousing is a worthwhile career option if you are having a passion of managing data. We at Multisoft systems are help here to aid you if you looking to crack Data warehousing interview. We are providing some of the most ask Data warehouse Interview questions that will surely help to get clear the interview. All the best!
- What is data warehousing?
Data warehousing is a central storehouse for all the data that is used by every department of the organization. This storehouse can be both physical and logical. Thus Data warehousing mainly concentrates on the process of collecting data and work on how that can be analyzed and retrieved afterwards. The concept of Data warehousing consist the following two approaches:
- Top-down approach
- Bottom top approach
- What is the main difference between data warehouse system and operational database?
Data warehouse: It is the assimilation of data that is relevant to the organization and later on can be used for analyzing within the organization.
Operational database: All the data that is being used by the company for transaction can be known as operational database.
A data mart is an access layer of data housewares environment that is widely used to collect the data transferred to the users. It is considered as the subset of data that is already stored in data housewares environment. Using data mart, data can be customized to a level from where the information can be taken a modified so that it can become useful information for the organization.
- Explain what is a dimension of data warehousing?
Dimension of data warehousing is classification where it classifies the facts in measures in a systematic fashion. It helps the users to describe and give essential solution for the business operations.
- What is a data cube and how does it help?
Data cube is a multidimensional database which is an improved version for OLAP applications and data warehouse. The query language used in cube is different from the query language that is used in traditional databases. It can be defined by the dimensions and the facts of how the data is represented in multidimensional cubes.
- Define what is warehouse management system?
A warehouse management system is software that enables organizations to manage and control warehouse operations. It provides storage functionality for all the organization data. The current day WMS has also provisioned with RFID and voice recognition capabilities.
- What are the important responsibilities of warehouse manager?
The important responsibilities of warehouse manager are:
- Performs integrity and consistency changes
- Create indexes regularly and updates where it is required
- Regular backups
- Grouping of the data as per the need from the data pool
- They are involved in in creating data models as per the need from the project teams
- Give due attention towards maintenance and development processes so that they meet the SOX guidelines.
- What is normalization?
Normalization is the process organizing the columns of the tables that are relevant to relational database. It reduces the redundancy of data and also improves the data integrity. Moreover, it also helps in simplifying the design of database so that the optimal structure is enabled.
- What is a fact table? Explain how many fact tables are there in a star schema?
A fact table is a table which contains information regarding facts, measurements and metrics of a business process. It is generally placed at the center of star schema. A fact table mainly consists two types of columns:
- The first column has the fact data
- The second column has the foreign key relation
In star schema, there is only one fact table. Thus multiple fact tables are stored in fact pattern schema.
- What is the main benefit of normalization?
Key benefits of normalization:
- It reduces the data redundancy.
- It helps to maintain valid data that is more useful to the users whenever it is required.
- Expand what DMQL stands for and what is the language that is used in DMQL?
DMQL is the abbreviation for Data Mining Query Language that is intended to support Ad hoc and interactive data mining. SQL is the language that is used in DMQL
- What does a slice operation mean? How many dimensions are used in slice operation?
Slice operation is the process of filtration in data warehouse. Only one dimension is used in slice operation.
- What is data modeling and what it includes?
A data modeling is a method of displaying the data view in the form of graphical way. The process of data modeling includes the following activities:
- Design the detailed data warehouse database
- Goes according to the pattern and principles of data warehousing and BI
- There are various data modeling tools that are where the data can be represent in graphical way.
The data warehouse modeling includes:
- Top-down drive approach
- Multidimensional model or often called star schema
- Fact tables and dimensions tables
- Normalization and renormalization
- What are the characteristics of a data warehouse?
The characteristics of a data warehouse are:
- The data parts can be renormalized so that further it can be simplified and enhance the performance for the same.
- Numerous queries are involved where large amount of data is retrieved based on the queries
- A wide assortment of data is stored and can be used whenever required
- The load of data controlled
- Planned queries and Ad hoc queries are very normal when it comes to data extraction.
- What is a snowflake in the data warehouse?
Snowflake is a dimensional modeling within the data warehousing environment. It is used to enhance the performance of the queries. Additionally, Snowflake concept is used in data marts and data warehouse to supports a particular set of queries.