Data Warehousing
by yogesh chavan
1. Allows more appropriate technology for queries and reports.
2. Defination:-A centralized repository of all data generated by all departments and units of a large organization is called Data warehouse.
3. Uses Of Data Warehousing
3.1. Data warehouse can be used for number of activities including traditional analysis , information visualization .
3.2. Business Analysis : For decision Making.
3.3. Forecasting :You can use historical profitability figures to estimate future revenue.
4. Data Warehouse Architecture
4.1. 1.Staging area:Staging area of the data warehouse is both a storage area and a set of processes commonly presentation area.
4.2. 2.Load Manager:
4.3. 2.2:Also called the front end component, it performance all the operations associated with the extraction and
4.4. 2.3:loading of data into the warehouse.
4.5. 2.4:These operations include simple transformations of the data to prepare the data for entry into the warehouse.
4.6. 3.Warehouse Manager:
4.7. 3.1:Performs all the operations associated with the management of the data in the warehouse.
4.8. 3.2:The operations performed by this component include analysis of data to ensure consistency,
4.9. 3.3:Transformation and merging of source data, creation of indexes and views, aggregations, and backing-up data.
4.10. 4.Query Manager:
4.11. 4.1:Also called backend component, it performs all the operations associated with the management of user queries.
4.12. 4.2:The operations performed by this component include directing queries to the appropriate tables and scheduling
4.13. 4.3:The execution of queries.
4.14. 5.ETL
5. Data Mining: Data mining automates the process of locating and extracting the hidden patterns and knowledge
6. Types of OLAP Servers :
6.1. MOLAP(Multidimensional Online Analytical processing)
6.2. ROLAP(Relational Online Analytical Processing)
6.3. HOLAP(Hybrid Online Analytical Processing)
7. Ware House Schema :The schema is a logical description of the entire database
7.1. 1.
7.1.1. Star schema
7.1.2. 2.
7.1.2.1. Snowflake schema
7.1.2.2. 3.
7.1.2.2.1. Fact constellation
8. Inmon the father of Data Warehouse defined Data warehouse as :"A Warehouse is a subjectoriented, integrated, time-variant and non-volatile collection of data in support of management's decision making process”
9. Advantages Of Data Warehousing
9.1. Provides a more simple query interface to users .
9.2. Easy way of reporting across multiple systems
10. Data Preprocessing techniques
10.1. 1.Data Cleaning
10.2. 2.Data Integration
10.3. 3.Data Transformation
10.4. 4.Data Reduction
11. Characteristics of Data Warehousing:
11.1. 1.
11.1.1. Subject Oriented
11.1.2. 2.
11.1.2.1. Integrated
11.1.2.2. 3.Time-variant
11.1.2.3. 4.
11.1.2.3.1. Non-volatile
12. Data Cube Operations
12.1. 1.Slicing
12.2. 2.Dicing
12.3. 3.
12.3.1. Rotating./Pivoting
12.3.2. 4.
12.3.2.1. Roll-up
12.3.2.2. 5.Drill up