Large-Scale Web Scraping: Data Extraction Problems You Should Know

Large-scale scraping has become a relevant topic among people due to the growing demand for big data. More and more people are eager to extract data from multiple websites to help develop their businesses.

However, as the scale of scraping processes increases, many problems arise, such as blocking mechanisms that prevent people from obtaining data. Let's look at the problems of large-scale scraping in more detail.

Problems of Large-Scale Web Scraping

1. Bot Access

The first thing to check is whether your target site allows scraping before you start using it. If you find that it disallows scraping via robots.txt, you can ask the site owner for permission to scrape, explaining your needs and goals. If the owner still does not agree, it is better to find an alternative site with similar information.

2. Complex Web Page Structure

Most web pages are based on HTML. Web page designers may have their own page layout standards, so web page structures vary widely. When you need to perform large-scale web scraping, you will have to create one parser script for each site.

Moreover, websites periodically update their content to improve user experience or add new features, leading to structural changes on the web page. Since parsers are configured according to the design of a particular page, they will not work on the updated page. Therefore, sometimes even minor changes to the target site require parser adjustments.

3. IP Blocking

IP blocking is a common method to stop scrapers from accessing website data. This usually happens when a site detects a large number of requests from the same IP address. The site either completely bans the IP address or restricts its access to interrupt the scraping process.

4. CAPTCHA

CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is often used to distinguish humans from scraping bots by displaying images or logic puzzles that humans solve easily but bots cannot.

Many CAPTCHA solvers can be embedded into bots to ensure uninterrupted verification. However, while CAPTCHA bypass technologies can help obtain continuous data streams, they can still slow down the large-scale scraping process.

5. Honeypot Traps

A honeypot is a trap that the site owner places on a page to catch scrapers. Traps can be links invisible to humans but visible to scrapers. Once a scraper falls into the trap, the site can use the obtained information (e.g., IP address) to block that script.

6. Slow Site Loading Speed

Websites may respond slowly or even fail to load if they receive too many requests. Of course, this is not a problem when people browse the site, as they need to reload the web page and wait for the site to recover. But scraping can be disrupted because the script does not know how to handle such an abnormal situation.

7. Dynamic Content

Many websites use AJAX to update dynamic web content. Examples include lazy loading of images, infinite scrolling, and fetching additional information when a button is clicked via AJAX calls. It is convenient for users to view more data on such sites, but not for scrapers.

8. Login Requirement

Some protected data may require you to log in first. After you enter your credentials, your browser automatically adds a cookie value to multiple requests you make on most sites, so the site knows you are the same person who just logged in. Therefore, when scraping sites that require login, make sure that cookies are sent along with the requests.

9. Real-Time Data Scraping

Real-time data reduction is necessary when it comes to price comparison, inventory tracking, etc. Data can change in an instant and can lead to huge capital gains for businesses. The scraper needs to constantly monitor websites and collect data. Even then, it still has some latency because it takes time to request and deliver data. Moreover, obtaining large amounts of data in real time is also a big challenge.

Scheduled data extraction at ESK Solutions can be performed with a minimum interval of 5 minutes, allowing you to obtain data almost in real time.

In the future, there will undoubtedly be new problems in the field of web scraping, but the universal principle is always the same: treat websites politely. Do not try to overload them. Moreover, you can always find a scraping tool or a contractor like ESK Solutions to help you with the scraping work or to place an order for custom web development.