Data & Process Modelling
Data and process notations, each as a diagram you can question and run.
Dimensional
Star schema
One fact table of measurements in the middle, surrounded by denormalised dimension tables that describe them. Every question is one join away.
Snowflake schema
A star whose dimensions are normalised into chains of smaller tables. Less repetition, more joins.
Galaxy schema
Several fact tables sharing conformed dimensions (also called a fact constellation). Different processes can be compared on the same date, product and store.
Relational
Entity relationship diagram
Entities, their attributes and the rules that connect them, drawn in crow’s-foot notation. The blueprint for a normalised, transactional database.
Data Vault 2.0
Splits every business concept into hubs (keys), links (relationships) and satellites (history). Built for integrating many sources and auditing every change.
Object & graph
UML class diagram
Object-based modelling: classes with attributes and behaviour, connected by inheritance, composition and other typed relationships.
Property graph
Nodes with labels and properties, joined by typed, directed relationships that carry properties too. Built for questions that follow connections.
Process
BPMN process diagram
Business Process Model and Notation: who does what, in which order, with decisions and parallel work, laid out in swimlanes.
Data flow diagram
Shows how data moves: from external entities, through processes that transform it, into and out of data stores. No timing, no decisions, just data.
UML sequence diagram
Who talks to whom, in what order, for one scenario. Time runs down the page; each arrow is one message between participants.
State machine diagram
The life of one object: the states it can be in, the events that move it between them, and the conditions that must hold. Anything not drawn is not allowed.