Big e-commerce companies in China are bracing for what is expected to be the world's largest online sale this year.

Large undertakings to satisfy the expected demand have been made. These include the deployment of 3 million workers and more than 3,000 aircraft and cargo ships.

Singles Day , held every Nov. 11, is expected to generate billions of dollars in sales and involve the order and delivery of more than 1.9 billion products. Analysts predict that pent-up demand from consumers might see this year's event break records.

Industry experts have said that owing to millions of consumers in China not allowed to travel abroad this year as a result of the pandemic most will likely turn to online shopping. The trend, dubbed "revenge spending," is expected to further drive sales during Singles Day.

Goods such as electronics, appliances and clothing are expected to be popular. However, a rise in demand for luxury brands is also expected.

"We anticipate ongoing international restrictions will cause a meaningful shift in Chinese consumers buying luxury online...Luxury brands have also risen to the occasion, with an estimated doubling in the number of luxury brands participating in Singles Day," analysts at market research company Agency China said in a report.

The event, which is also called Double 11, was created by online retail company Alibaba Group. Other big retailers, such as JD.com, have launched similar events. However, Alibaba's has remained dominant in terms of sales and the number of items sold.

Last year's event generated gross sales of more than $31 billion - more than double that of sales generated during Black Friday and Cyber Monday combined. Just a minute into the event, sales surpassed $1 billion.

Alibaba said its logistics arm Cainiao would charter more than 3,000 flights and sailings. The company said that more than 3 million people across its facilities will be involved.