Week 2: File Systems
In the Previous Class
• Introduction
• The difference between data and information
• What is a database?
• Database Management Systems
• Types of databases
• Database design
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Database Systems: Evolution, Components, and Functions - Week 2 Lecture Notes, Summaries of Database Management Systems (DBMS)
These lecture notes delve into the evolution of database systems from file systems, highlighting the problems associated with traditional file systems and the advantages of using a database management system (dbms). The notes cover key components of a database system, including data dictionary, data storage management, and security management. They also explore the functions of a dbms, such as data integrity management, backup and recovery, and data access languages. Finally, the notes discuss the disadvantages of database systems, including increased costs and vendor dependence.
Typology: Summaries
2024/2025
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Week 2: File Systems
In the Previous Class
- Introduction
- The difference between data and information
- What is a database?
- Database Management Systems
- Types of databases
- Database design
Outline
• RECAP!
- How modern databases evolved from file systems
- Problems with the computerized file system
- The Database system
- Components of the database system
- Functions of a database management system (DBMS)
- Disadvantages of a database system
- Database Career Opportunities
Recap
- Databases store two kinds of data: End-user Data and ???
Recap
- What is Meta-data?
Recap
- Give Examples of database management systems (DBMS)
Recap
- What DBMS are we using in this course?
Outline
- RECAP!
- How modern databases evolved from file systems
- Problems with the computerized file system
- The Database system
- Components of the database system
- Functions of a database management system (DBMS)
- Disadvantages of a database system
- Database Career Opportunities
Evolution of File System Data Processing
- Manual File Systems ▪ Pen and paper systems put into folders and filing cabinets
- Computerized File Systems ▪ Data processing (DP) specialist : Created a computer-based system that would track data and produce required reports
An Example file from a file system
Exercise: An Example file from a file system
How many records are in this file? How many fields are in this file?
Figure 1.8 - A Simple File System
Sales department Personnel department
Types of file systems continued…
- File System Redux: Modern End-User Productivity Tools ▪ Widespread adoption of personal computers and spreadsheet programs like Microsoft Excel in business. ▪ Users favour direct, hands-on access to data, leading to increased use of spreadsheets for data analysis and decision making. ▪ Over-reliance on spreadsheets, often for tasks they are not ideally suited for. ▪ Misuse of spreadsheets as a substitute for databases, mimicking the old manual storage methods. ▪ Resulting issues similar to early computerized data file systems: data duplication, inconsistency, and scattered “file systems” due to multiple users creating separate spreadsheets.
Problems with File System Data Processing
- A critique of the file system method serves two major purposes:
- Understanding the shortcomings of the file system enables you to understand the development of modern databases.
- Many of the problems are not unique to file systems. Failure to understand such problems is likely to lead to their duplication in a database environment, even though database technology makes it easy to avoid them.
Problems with File System Data Processing
- Data Redundancy ▪ Having many data files with overlapping data
- Complex system administration ▪ No means of controlling or managing the data consistently across all of the files
- Lengthy development times ▪ For data retrieval
- Difficulty of getting quick answers (quick reports)
- Lack of security; limited data sharing ▪ Difficult to program; often omitted
- Extensive programming