ISYS3257 Lecture Notes - Disk Array, Data Integrity, Tablespace

• School: Boston College
• Department: Information Systems
• Course: ISYS3257
• Professor: Mary Ellen Spang

Document Summary

Purposes of dbms: create a single point of entry to and ownership of the data to ensure consistent application of technical and business rules and access. The dbms process owns the files that hold the business information. As the owner, it can force all access through its own mechanisms, enforcing all rules in the catalog. No other user can use a back-door to violate the business rules and constraints on the data: provide concurrent access to database information. The dbms owns the files and is the only user as far as the operating system is concerned. Internally, it can manage multiple users of the dbms granting them access to a single data source (i. e. a single record) because it can check to ensure that the data remains consistent and accurate. The dbms locks individual records, rather than entire files (like the operating system) so multiple users can use the database simultaneously.