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Comment by protospork | Hacker News Reader

> retail POS generates a large amount of transactional data, and you need low latency for database syncing and credit card/loyalty card transactions.

I've always been curious about what sort of infrastructure the average big-box retail store actually needs. My local Walmart can't have anything but a wireless uplink, unless they actually installed 5+ miles of fiber or something when they built the store.

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This Quora answer gives a little insight in to the needs of a modern store: http://www.quora.com/What-is-the-new-instantaneous-payment-s...

Also these stores basically couldn't exist without robust inventory management systems. There is probably more technology in the average big box than we realize.

I was told that every time an item is scanned at the register at any Walmart store, it updates an inventory database in near real-time (I assume there is some sort of message queue with that kind of volume and distribution). Then their system automatically places replenishment orders with their vendors when the inventory of that item goes below a certain level. They are a well-oiled machine, focused on making sure that they almost never lose any sales due to being out-of-stock, nor waste money on carrying excess inventory in their warehouses. Mismatching inventory to sales will drive a retailer out of business very quickly.

This is also part of the reason why they are able to push "everyday low prices" instead of discounts. Discounting is what you do with the excess inventory when you messed up and ordered too much of something.

The system is Retail Link and there's quite an ecosystem around it.

Working for a regional grocery retailer from the mid-90's to the mid-2000's, I can assure you that not nearly enough consideration was given to bandwidth needs when designing and building new stores. I remember, as late as 2002, having an entire store run off of something like a 512kbps circuit.

We literally shipped register (paper) journal tapes back to the warehouse via truck mail.

Time/date/UPC. That should fit over a 9600 modem line, and that's before you add compression.

More like time/date, UPC, quantity, item description, price, coupons, sale discounts, sales tax, rebate info, clerk info, customer info, payment info, and more. Times dozens of items per receipt, times dozens of registers. All continually operating 12+ hours a day. All needing low-latency access to master databases, credit card servers, and banks.

Trust me, retail is big. Like "Big Data" big. There is more data there than you think. ;)

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