CS338 Lecture Notes - Lecture 14: Machine-Readable Medium, Conceptual Schema, Computer Data Storage
24 Apr 2019
School
Department
Course
Professor
Document Summary
Collection of concepts that describe the structure of a database. Provides means to achieve data abstraction: suppression of details of data organization and storage, highlight essential features for improved understanding of data. Includes basic operations: retrievals and updates on database. Dynamic aspect or behavior of a database application: allows database designer to specify a set of valid operations allowed on database objects. High level or conceptual data models: close to the way many users perceive data, eg. Low-level or physical data models: describe details of how data is stored on computer storage media. Include explicit access paths: structure that makes locating particular database records efficient, eg. Index: allows direct access to record by looking up a value. Compromise: representational data models: abstract model of data, emphasize aspects that should be understood by end users, close enough to how data organized in computer storage that they can be implemented efficiently. Internal level: describes physical storage structure of the database.
