What are Types of Facts

What are Types of Facts?

·         Additive: Additive facts are facts that can be summed up through all of the dimensions in the fact table. A sales fact is a good example for additive fact.

·         Semi-Additive: Semi-additive facts are facts that can be summed up for some of the dimensions in the fact table, but not the others. 

       Eg: Daily balances fact can be summed up through the customers dimension but not through the time dimension.

·         Non-Additive: Non-additive facts are facts that cannot be summed up for any of the dimensions present in the fact table. 

       Eg: Facts which have percentages, ratios calculated.

What is Fact table

What is Fact table?

Fact table contains measurements of business processes also fact table contains the foreign keys for the dimension tables. 

For example, if your business process is paper production then average production of paper by one machine or weekly production of paper would be considered as measurement of business process.

What is Data Warehousing

What is Data Warehousing?

A data warehouse is a subject-oriented, integrated, time-variant and non-volatile collection of data in support of management's decision making process.

1. Subject-Oriented: A data warehouse can be used to analyze a particular subject area. For example, "sales" can be a particular subject.
2. Integrated: A data warehouse integrates data from multiple data sources. For example, source A and source B may have different ways of identifying a product, but in a data warehouse, there will be only a single way of identifying a product.
3. Time-Variant: Historical data is kept in a data warehouse. For example, one can retrieve data from 3 months, 6 months, 12 months, or even older data from a data warehouse. This contrasts with a transactions system, where often only the most recent data is kept
4. Non-volatile: Once data is in the data warehouse, it will not change. So, historical data in a data warehouse should never be altered.

What are the types of Slowly Changing Dimension?

What are the types of Slowly Changing Dimension(SCD)?


Type 1 Slowly Changing Dimension(SCD): 
The new information simply overwrites the original information. In other words, no history is kept.

Advantages:
- This is the easiest way to handle the Slowly Changing Dimension problem, since there is no need to keep track of the old information.

Disadvantages: 
- All history is lost. By applying this methodology, it is not possible to trace back in history. For example, in this case, the company would not be able to know that Christina lived in Illinois before.


Type 2 Slowly Changing Dimension(SCD):
A new record is added to the table to represent the new information. Therefore, both the original and the new record will be present. The new record gets its own primary key.

Advantages: 
- This allows us to accurately keep all historical information.

Disadvantages:
- This will cause the size of the table to grow fast. In cases where the number of rows for the table is very high to start with, storage and performance can become a concern.


Type 3 Slowly Changing Dimension(SCD):
There will be two columns to indicate the particular attribute of interest, one indicating the original value, and one indicating the current value. There will also be a column that indicates when the current value becomes active.

Advantages:
- This does not increase the size of the table, since new information is updated.
- This allows us to keep some part of history.

Disadvantages:
- Type 3 will not be able to keep all history where an attribute is changed more than once.

Microsoft Power BI - Why Power BI

Power BI is a Business Intelligence tool by Microsoft. Tableau and QlikView are market leaders now. MS-Power BI tool is very user friendly and easy to learn.

There are 2 variants of Power BI tool

Power BI Desktop - provides desktop based interface contains a whole suite of tools to build models and create visuals

Power BI Services - provides cloud-based BI services to create visuals and sharing the reports/dashboards online.

Why Power BI?

Below are some of the reasons to choose Power BI tool.

1.     Brand: - This is the Business Intelligence tool provided by Top Brand of Computer/IT; that is Microsoft. (Name is enough).

2.     Easy to Use: - Not only user friendly but easy to use; even beginner can start this after having a look at online forum or training videos.

3.     Cost: - Cost is the major factor for Business Intelligence tool as many people/industry avoid this due to high cost. But the MS-Power BI is much cheaper than the other tools Tableau or QlikView. 

4.     Community: - Pleasure news is the community creation by Microsoft where you will find many Experts/developers are ready to give you answer. http://community.powerbi.com you will find there are 2-3 posts per minute in community.

5.     Security: - It provides good security features as they allow to access only for organizational e-Mail account. (Sorry Gmail, Yahoo users). You can share with only for the organizational accounts. (note you can create Public link with limited features)

6.     Cloud Based:- Power BI is SaaS (Software As A Service) , even you can design and access your reports and design same from anywhere, where Internet network connectivity available.(this saves lot of physical hardware investment)

7.     Mobile Friendly: - Unlike many other tools, no additional design efforts required for mobile devices. All the Power BI reports are responsive and they adjust according to the device resolution.

8.     Data Access: - You can import Data set not only from Microsoft but other providers also like Oracle, MySQL, IBM DB2, SAP Hana, Google Big Query and many more.

Power BI Desktop vs Power BI Service