Table of Contents Link to heading
Traditional And Physical Data Storage Link to heading
- Limited by physical size
- Limited multi-access - a borrowed book can only be viewed by one person at a time.
- Limited search methods (title, author, subject)
- Slow turn-around
- Multiple indexes that must be rigorously maintained.
- Complex Query Limitations - vast amounts of time wasted counting the number of books on a subject or by an author.
- Anomalies: - What IFs:
- A card is misplaced?
- A catalogue card is misplaced?
- An item is entered into / deleted in one index but not the others?
Image Source:
Britannica
Modern And Digital Data Storage Link to heading
Data can now be stored in files, such as text files, Excel sheets, Word documents.
Image Source: Orange
Matter
Advantages Link to heading
- Low cost.
- No extra software / hardware is needed.
Disadvantages Link to heading
- Size - the larger the volume of data, the slower the retrieval of them (yet still better than physical data).
- Update / Synchronisation - files are hard to share. Updates from multiple users often end up with multiple versions of the same file or even overwriting someone’s changes!
- Accuracy - duplication is wasteful and can cause confusion (inconsistent data).
- Security - restriction to some fields is more difficult to manage (e.g., taxFileNumbers, IDs + usernames).
Database-System Applications Link to heading
Database systems are used to manage collections of data that:
- are highly valuable,
- are relatively large, and
- are accessed by multiple users and applications, often at the same time.
Here are some representative applications:
- Enterprise Information
- Sales: For customer, product, and purchase information.
- Accounting: For payments, receipts, account balances, assets, and other accounting information.
- Human resources: For information about employees, salaries, payroll taxes, and benefits, and for generation of paychecks.
- Manufacturing: For management of the supply chain and for tracking production of items in factories, inventories of items in warehouses and stores, and orders for items.
- Banking and Finance
- Banking: For customer information, accounts, loans, and banking transactions.
- Credit card transactions: For purchases on credit cards and generation of monthly statements.
- Finance: For storing information about holdings, sales, and purchases of financial instruments such as stocks and bonds; also for storing real-time market data to enable online trading by customers and automated trading by the firm.
- Universities: For student information, course registrations, and grades (in addition to standard enterprise information such as human resources and accounting).
- Airlines: For reservations and schedule information. Airlines were among the first to use databases in a geographically distributed manner.
- Telecommunication: For keeping records of calls, texts, and data usage, generating monthly bills, maintaining balances on prepaid calling cards, and storing information about the communication networks.
- Web-based services
- Social-media: For keeping records of users, connections between users (such as friend/follows information), posts made by users, rating/like information about posts, etc.
- Online retailers: For keeping records of sales data and orders as for any retailer, but also for tracking a user’s product views, search terms, etc., for the purpose of identifying the best items to recommend to that user.
- Online advertisements: For keeping records of click history to enable targeted advertisements, product suggestions, news articles, etc. People access such databases every time they do a web search, make an online purchase, or access a social-networking site.
- Document databases: For maintaining collections of new articles, patents, published research papers, etc.
- Navigation systems: For maintaining the locations of varies places of interest along with the exact routes of roads, train systems, buses, etc.
Adapted from Database System Concepts (2019) by Silberschatz, Korth, and Sudarshan.
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