HEY THERE.
TERMS
DATA MODELLING - Data Modelling is the process of analyzing, organizing and defining data using visual representation, to highlight trends , reveal patterns amd relationships between the data.
A schema - A schema is a formal description structure of a database.
A fact table - A fact table is the main table that is used to describe events that have taken place.
*A dimension table *-A dimension table also called lookup is a table that holds information about categorical fields in the fact table. It describes the features of a dataset.
DATA MODELLING
Types of data model
- Conceptual Data Modelling A conceptual data model is mainly used for business concepts. It mainly focuses on understanding and identifying the business terminology and concepts and how they relate.
The conceptual data model helps one get a better understanding of what to take into consideration by looking at the the "bigger picture" based on the solution of your data.
- Logic Data Model
Unlike the conceptual data model, the logic model is more detail and precise .
A logic data model provides a more detailed view of how entities relate to each other and the attributes associated with each entity guiding the implementation phase .
This model acts as a practical step towards the implementation of data.
- Physical Data Model
A physical data model specifies how data is stored and accessed in a specific database system. It requires the knowledge of the database management system (DBMS) indexing, compression and distributing options.
Its purpose is to store data in a robust manner that enables high performance and takes into accounts the technical detail of the
chosen technology.
Physical models deals with downstream data that already exist with predefined schemas, which should not be lost in the process of integration in order to get correct data types and metadata.
For a good data model practices the following should be done:
One should limit data imports to enhance great performance
Turning off time intelligence- When on it automatically creates a date/Time Hierarchy, and when a hierarchy is created an additional table is added which can bloat the power bi causing a slow down in rendering the visuals.
**
SCHEMAS
**
I) STAR SCHEMA
In a star schema a fact table is at the center while dimension table are positioned at each point of the star.
A fact table is made up of values that can be summarized and aggregated as well as one or many keys that link dimension tables.
The key is used to create a link or connection between tables.
The star arrangement allows easy navigation and analysis of data.
A star schema can be used when you need simple ,fast queries and straightforward model.
It can also be used for quick insights by business users.
II) SNOWFLAKE SCHEMA
A snowflake schema is a variation or extension of a star schema where dimension tables are normalized, meaning they are broken down into additional related tables.
A snowflake can be used when:
-Your data has high level of complexity or maintaining data integrity and reducing redundancy.
-Can be used in data warehouse where detailed analysis and reporting are required.
RELATIONSHIP IN POWER BI
Types of Relationships in POWER BI
I) Direct Relationship - This is a connection between two tables.
The tables are linked based on one or more common fields.
II) Multiple Relationships -This a connection or link between two or more tables in power bi.
III) Cross -Filter Direction- Cross -Filtering determines how filters applied in one affect related tables in the relationship.
Top comments (0)