Informatics Practices · Ch 1 — Computer System
Data Capturing, Storage, and Retrieval
Data Capturing, Storage, and Retrieval
Processing data is never a single act — it is a cycle. Data must first be brought into the system in digital form, then kept safely in a file or database, and finally fetched back out whenever it is needed for further action. These three stages — capturing, storage and retrieval — each come with their own methods and their own challenges.
(A) Data Capturing
Data capturing is the process of gathering data from different sources in digital form. The sources and instruments vary enormously:
- a keyboard, for direct manual entry;
- bar code readers, of the kind used at shopping outlets;
- remote sensors mounted on earth-orbiting satellites;
- comments and posts across multiple social media platforms, which are also captured as data.
Because these sources are so different from one another, the data they produce differs in form as well — and this heterogeneity among data sources is what can make capturing a complex task.
(B) Data Storage
Data storage is the process of keeping the captured data so it can be processed later. Data today is being produced at a very high rate, which has made storage a genuinely challenging task; what has kept it manageable is the steady fall in the cost of digital storage devices, with numerous such devices available in the market.
Two practical realities follow:
- Storage must grow with the data. Data keeps increasing with time, so storage devices need to be upgraded periodically.
- Large organisations use data servers. These are computers fitted with larger and faster storage, deployed to hold vast amounts of data; such dedicated machines help in processing data efficiently. Their drawback is cost — both the hardware and software expense of setting up a data server, and its ongoing maintenance, are high, which weighs especially on small organisations and startups.
(C) Data Retrieval
Data retrieval means fetching data from the storage devices so it can be processed according to the user's requirement. The difficulty here scales with size: as databases grow, the challenge of searching and retrieving data within an acceptable time grows with them. …
The figure is a single photograph of a handheld barcode reader caught in the act of scanning. The device is gripped in the hand and pointed at a printed barcode — the familiar pattern of parallel black and white stripes found on product packaging — and a red scan beam shines out of the reader onto the code. That red line of light is the working part of the device: as it sweeps across the stripes, the reader senses how the bars and spaces reflect the light differently and converts that pattern straight into digital data.
The photograph belongs to the discussion of data capturing, the first stage of working with data. Before any data can be stored or processed, it has to be brought into the computer in digital form, and a barcode reader is a classic capturing device. Instead of a shop assistant typing a long product number on a keyboard — slow, and easy to get wrong — one pass of the red beam over the barcode captures the product's identity instantly and accurately. This is exactly why such readers are standard equipment at the billing counters of shopping outlets. …