Maintenance, Cost, and Quality: The 4th – 6th Challenge in Web Data Acquisition Project

Hello again. We have three more challenges to cover: Maintaining, Cost, and Quality.

Let’s first do a quick recap. We have covered the first three challenges you can run into in web data acquisition projects: Setup, Banning, and Scaling.

Now, in order to properly talk about the challenge in Maintaining a data acquisition project, let’s first have a look at Cost and Quality.


It really takes a village to produce a data feed and to keep the data feed flowing.

Here are the cost components in a typical data acquisition project

  • Cost of IP (proxy) rental / subscription
  • Crawl engineers
  • QA engineers
  • Data engineers
  • Project managers

If you’re doing your data acquisition in-house, these are the things you need to account for in your cost model. When you’re buying rather than doing it in-house, these are the things you’re really paying for. When shopping for data vendors, it makes sense to try and understand your monthly cost for these items as a baseline for comparison. Data vendors usually charge monthly recurring fee for the subscription of the data — sometimes with a setup fee for the service and other deliverables.

It is also crucial to think not only of the cost you will incur but also in terms of opportunity cost — what revenue are you sacrificing by allocating your resources to focus on these data acquisition activity rather than activities that are closer to the core of your business? How to ensure you’re making a sensible trade-off?


What do we mean by quality? There are two main type of issues around quality in web data acquisition projects.

  1. Quality of data (item coverage, field coverage, field accuracy)
  2. Quality of service (when working with DaaS vendors or any SaaS vendor for data acquisition toolings)

These two issues will inevitably occur in data acquisition projects once it hit a certain scale and stage.

Quality of data

Three types of data quality issues:

  • Item coverage. The level of record / item that’s collected against what’s expected. When you collected 90k records from 100k that’s on the website / data source, that means you have an item coverage of 90%.
  • Field coverage. The level that a record / item contains the field. E.g. when 15% of the 90k records don’t contain product price information that actually exist on the website / data source (failure in picking up that field at all), that’s 85% field coverage score for the product price field.
  • Field accuracy. The level that a record / item contains the field with the expected information. E.g. when 5% of the 90k records contain truncated product title information compared to what’s on the website / data source (failure in picking up that field correctly), that’s 95% field accuracy score for the product title field.

You see this is exactly the three parts you want to ensure you have early detection systems, scenario handling, and fallback plan for — that we talked about last week.

Quality of service

  • When you get into a DaaS (Data as a Service) engagement, there are certain SLAs the vendor will offer. These usually include response time, resolution time, delivery guarantee, and all the items in the quality of data aspect above.


Now, what are the different things we actually need to maintain in order to keep the data flowing?

  1. Code: monitoring, fixes
  2. Infrastructure: healthy pool of IPs, server uptime and health, storage, RAM, CPU
  3. Team. hiring, training, retention, management

It pays to be proactive with our maintenance efforts. Once it’s running, how can you know when datafeed is healthy, what’s your plan if something breaks, and how do you know which part has broken?

Don’t step on the gas before putting your seatbelt on. Set up your monitors upfront.

Common monitors to implement for each crawler in your project:

  • Less items than expected
  • Deviation / quantity drop
  • Field not populated (extractor breakage)
  • Runtime error

Running and maintaining a web data acquisition project is even more complex than maintaining most software development and service delivery because in web data acquisition projects, we are interacting with third party systems that often are deliberately trying to keep us away making it a fragile and high-maintenance piece of work.

Closing thoughts

That wrapped up this series. Now that we have seen all six challenges, it became clear that if you do your data acquisition in-house, then you will be managing all six challenges. But if you get your data from data vendors, you will primarily only deal with two types of challenges: cost and quality of their services. This is the reason many companies decide to outsource all or some of the data acquisition process.

It might seem dry and abstract at this point but these are the basic framework and language of data acquisition project management that we will keep coming back to and base many of future discussions on. For example if you are considering launching a data provider service / becoming a data vendor, we can map different customer journeys and product opportunities from these six challenges because they are essentially the pain points of your potential customers.

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