Write a program not in Database Languages, e.g. SQL but in a high-level language, e.g. C++, Java, or Python, etc.
to implement a File System for the tables demonstrated (one file for one table) in Sept. 2 class: Fig. 1.2 (a) and (b) and the resulting table by join/merging of the two tables as in Fig. 1.4.
Functionalities of the File System includes, e.g.:
1) Creating the tables.
Insertion of the records, and add operations of the tables,
such as sorting by one attribute, retrieval of information, the connection of tables including natural join operations, to generate another table, input/output the whole or partial (like view in the database) records of the tables etc.
2) Access to the data in tables to
e.g. Retrieval of information stored in the tables
Insertion of new information into the tables
Deletion of information from the tables
Modification of information stored in the tables
3) Operations between tables
The operations (functions, features, etc.) of the file system shall be implemented like what DDL, DML in SQL can do. (Selection Projection, grouping, aggregation, etc. within a table, set operations, i.e. operations among tables: such as Set operations: Union/Interception difference Selection, Projection, Cartesian product and Join/Merge two or more tables, etc.)
Due to the time limit, try the simple functions first and get more and more later. No need to get it all complete when this work is done individually until later (after this assignment) we might go for teamwork for covering more functions.
Deliverables:
Again, for any program in high level language or SQL
- Attach the necessary documentation (can be embedded in comments of the program) to cover a software process SDLC briefly e.g. Requirement, Analysis, Design, Implementation code, Testing, and Deployment/Maintenance which instructs users how to run your program and specify what you have done in the program and what you did not finish, etc,
- The program shall offer clear UI user interface so users know how to run your program.
- At the end of program, attach various TESTING CASES within the comments to show how capable and how many cases your program can handle.
Notes:
Drawbacks of using file systems to store data
o Data redundancy and inconsistency
Multiple file formats, duplication of information in different files
o Difficulty in accessing data
Need to write a new program to carry out each new task
o Data isolation multiple files and formats
o Integrity problems
Integrity constraints (e.g., account balance > 0) become buried in program code rather than being stated explicitly
Hard to add new constraints or change existing ones
o Atomicity of updates
Failures may leave database in an inconsistent state with partial updates carried out
Example: Transfer of funds from one account to another should either complete or not happen at all
o Concurrent access by multiple users
Concurrent access needed for performance
Uncontrolled concurrent accesses can lead to inconsistencies
Example: Two people reading a balance (say 100) and updating it by withdrawing money (say 50 each) at the same time
o Security problems
Hard to provide user access to some, but not all, data
