what's data modelling;
Its a concept used in power bi in organizing tables and defining relationships between them. Its the art of analyzing defining of different data types where relationships between bits of da ta are created.
Some of the benefits of data modelling:
1.saving time and money
It saves time and lots of process in investments through appropriate planning.
2.Well structured data system
With data modelling one is able to connect between business and able to do analysis easily.
3.Reducing errors
it reduces errors by ensuring non redundant data doesn't enter in your data system.
4.Tracking and setting target.
Give's indicators and timely tailored performances targets to your business objectives.
An example of data modeling in power BI as shown in the diagram below.
SCHEMAS
They are logical framework and organization of tables, relationships and data structure with a sematic model acting as the blue print.
We have different types of schemas;
1.Star Schema
This most used type of schema used in powerbi.Star schema is a mature modeling approach widely adopted by relational data warehouses. It requires modelers to classify their model tables as either dimension or fact.
An example of star schema.
What is a fact table;
A fact table contains dimension key columns that relate to dimension tables, and numeric measure columns. The dimension key columns determine the dimensionality of a fact table, while the dimension key values determine the granularity of a fact table.
Generally, dimension tables contain a relatively small number of rows. Fact tables, on the other hand, can contain a large number of rows and continue to grow over time.
2.Snow flake schema
snowflake schema is a type of data modeling technique used in data warehousing to represent data in a structured way that is optimized for querying large amounts of data efficiently It is a variant of the star schema, where the centralized fact table is connected to multiple dimensions. It has several key characteristics;
- Hierarchical Structure: The schema has a hierarchical structure organized around a central fact table.
- Multiple Levels: The schema can have multiple levels of dimension tables, allowing for more granular analysis of data.
- Joins: The schema typically requires more complex SQL queries involving multiple table joins. -Joins: The schema typically requires more complex SQL queries involving multiple table joins.
Example of a snowflake kind of schema.
schema patterns between star and snow flake schemas.
Among the two the most used is the star schema is the most used as its easy to do understand and its well defined to allow faster querying and smooth report interaction.
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