- A logical blueprint of how data is organised and stored in a DBMS.
- Having various levels of schema helps with data abstraction
Types of schema §
- Physical or Internal Schema
- A blueprint of the file organisation, indexing and storage allocation
- Abstracted from the user and handled by the DBMS software itself
- Logical Schema
- Blueprint of the various tables, relationships, constraints and data types
- Used by developers when querying for data
- External schema
- Talks about how the data is presented to the user
Schema types in a Data Warehouse