2 hazardous bottlenecks that can crash your ecommerce website

Flash sales. Seasonal sales. Product releases.

Running these online events creates the opportunity to attract more customers than any physical store ever could. Making the profit upside even greater, customers are almost twice as likely to convert during a promotional sale like Black Friday.

Traffic during a successful sale can easily exceed what you might have predicted. While this is cause for celebration, you might end up scrambling to cope with the demand before you can even pat yourself on the back.

Website technology failure will ruin a sale event, leaving money on the table for your business. Even worse, it transforms the positive hype and excitement of your shoppers into frustration that lasts long after the sale.

For online retailers, promotion for the event is only half of the story. Without a solid technical foundation allowing the website to handle peak traffic spikes, promotion efforts go to waste.

How do you maintain your online services during this brief period with tremendous demand?

The points in your customer’s buying journey where key technical activities occur – your inventory database, your checkout payment systems – are often overlooked. But they’re critical to ensure a successful sale.

The misconceptions of server capacity, infrastructure & re-platforming to support high-traffic sales

Upgrading servers or increasing system infrastructure is a common first thought to support a vast number of visitors.

Others will consider adopting cloud-based services or ecommerce platforms, since cloud-based systems do not have the limitations of physical servers.

This gives businesses a perception of unlimited scalability to handle large concurrent demands.

These ideas might sound like the ultimate solution to cope with visitor peaks. They can be effective for browsing because they can hold more people on the site.

But they’re ill-suited to support the full customer journey since they neglect the real bottlenecks in transaction backend services.

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1. Database performance bottlenecks in the inventory system

The transactional database is one typical bottleneck of an ecommerce application.

The locking system synchronizes with the inventory system. It places customers’ items on hold and reserves it for them for a specified time frame while they complete their purchases.

If a customer decides not to complete a purchase in the designated time frame, the lock is removed, and the next customer in line can reserve the specific item.

Since these types of database transactions must be centralized, the entire process creates major slowdowns under high traffic load.

Since you’re dealing with limited quantities of physical merchandise for seasonal sales or product launches, you must preserve database integrity for order and stock volumes. If a shopper just bought the very last item, the website should immediately reflect the item is out of stock for the next shopper.

Preserving this data integrity is complex and requires systems to be highly unified, which deteriorates website performance.

The worst-case scenario of database system failure is the security threat of shoppers’ personal and credit card data being compromised.

But there are other problems, too.

Related: Are You Guilty of Falling for These 5 Ecommerce Myths?

If the database isn’t functioning properly and these calls are not delivered at the speed of the requests, orders could get mixed up. Your web application could sell the same item of inventory multiple times. 

Controlling the website traffic and throughput based on the locking mechanism’s operating speed is the only way to safeguard against the massive influx of customers attempting to reserve inventory of limited or deep-discount items.

If the database can handle the increased rate of inventory locking, congratulations!

However, the next technically-complicated step, checkout, represents another potential application performance bottleneck during your hyped sale or registration.

With the increased conversion rate and your rate of sale (the speed at which customers are trying to checkout), your web application is liable to be overwhelmed.

2. Payment gateways overheat from the sharp increase in transactions

The payment system is another common weak point for online transactions.

Most credit card services are provided by third-party vendors via payment gateways. The gateways perform a variety of technical checks and verifications to process secure financial transactions.

These verifications come at a cost. And the latency of completing the transaction can slow from 2-3 seconds on your average day to 5-10 seconds at high traffic times, all depending on the numbers of payment authorizations needed. The length of and variation in this lag renders the payment system unstable when confronted with high online traffic.

Beyond the time the payment verification requires, payment gateway providers have a finite number of transactions they can handle. So, on Black Friday or iPhone release day when a payment processor is expected to handle 10x the normal number of transactions, something is bound to go wrong. 

Importantly, it’s not only small business with their own hosted websites or lower-tier subscriptions with ecommerce platforms that are harmed.

The same payment processors are used by enterprise-level companies, meaning their shoppers are also at risk of being impacted.

How can the bottleneck issue be solved?

Now that you understand where the typical bottlenecks are, how can you address the performance issue?

You can certainly invest time and money to scale servers and buy the fastest databases and payment systems. But as you've seen, you’re not sure to overcome the challenges of your highest demand days.

Related: Autoscaling Explained: Why Scaling Your Website Is So Hard

The bottleneck is the transactional database or the payment system, which is not something you change simply by scaling up to cope with the visitor peak during the flash sale period.

Online flash sales are becoming more common. Limited-edition product releases are a magnet for trend-following brand loyalists. You want to be prepared when web traffic surges suddenly on your website.

You can avoid database overload and payment system failure when including a virtual waiting room system in your technology strategy. You can implement the system to control the traffic and speed of customers. It redirects customers to a queue page and then passes them back at a speed your shop can handle. This is done in an ordered sequence that ensures fairness across all the customers seeking the same high-demand products.

Related: Learn Why Top Enterprises Turn to Queue-it to Manage High-Demand Sales

If you are planning an online sale event that will attract significantly higher traffic or a significantly higher conversion rate, a virtual waiting room will be key to avoiding major performance issues and customer uproar.

(Editor's Note: This post has been updated since it was originally written in 2017.)