[chaz]

Walmart's DW was 2.5 petabytes in 2008; undoubtedly larger now. Rumor had it that they were storing every line item from every POS receipt since the early 90s, but they probably don't have all that data online. I would think it needs to contain POS data, SKU inventory and sales at every store and distribution center, tracking of vendors, orders, shipments, truck logistics, etc. Even weather reports (remember how they predicted Poptarts would sell more when hurricanes were forecast?).

eBay has a 9 petabyte DW that cuts across all of the types of data on their whole site: listings, bids, feedback, categories, clicks, etc.

Sometimes big data is actually big data, both in terms of raw size as well as complexity.

http://gigaom.com/2013/03/27/why-apple-ebay-and-walmart-have...