Notes on a tour of an Amazon distribution facility (2014)

Bonus quote: "Our tour guide used an iPhone, but claimed he’d use a Fire if he wasn’t locked into his carrier."

I wished they would add a diagram, even if it's just hand-drawn. It's would have been much easier to visualize, especially the detailed parts.

Also the naming is sometimes inconsistent across the different authors. e.g. Sometimes folks are called "associates", sometimes "sorters". It got confusing quickly. Would be nice if the naming was clearer

The manual system isn't that different from the Sears "schedule system" introduced in 1908.[1] Note the line "pickers don't necessarily pick items for a single or even complete order." That's crucial. Orders are split apart and combined pick lists generated. Picked items then flow towards order assembly stations, which Amazon calls "sort". At any one time, some maximum number of orders are in progress, limited by the number of output boxes at order assembly. Amazon does this with computers; Sears did it with clerks and pick slips, with Sears giving each order an assembly bin for a fixed number of minutes.

Separating picking from order assembly and inserting a sort phase reduces the order of the problem. Picking N orders from M items individually means O(N × M) cost, because as inventory becomes larger, the pickers travel more distance. With separate picking and assembly, performance is something like O(log(M) × N) cost, because each picker works in a limited area. That was Sears' big breakthrough.

[1] https://news.google.com/newspapers?nid=1734&dat=19721006&id=...

So, you'd think there would be some logic to how the items were distributed and not just the whim of the associate. (Or maybe that's good enough.)