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Then how does Domino's get me a pizza within 30 minutes?

I love that response :-) Imagine that your Pizza joint is in a city where there are no signs on the street, at first when the Pizza delivery trucks pulls out, he shouts really loudly "Where the hell does fsk live?" and from one of the street corners someone says "Down that way." so he goes along, periodically shouting at intersections trying to find his way. Sometimes he has to cross bridges, except these are very special, at any time they can just collapse and drop all of the traffic into the river, too bad, so sad. Or people on the corners can keep saying "he lives this way..." until the driver realizes he is going in a loop and his pizza is very cold, and not worth delivering anyway. Or my personal favorite, the pizza guy is driving along and suddenly, BLAM! someone pulls out of their driveway at high speed demolishing the pizza guy's car! Now both drivers get out, go back to where they started, pick a random number between 1 and 10, count and then start out again.

That you get Pizza at all is a freakin' miracle!

Something about this immediately conjures up Snow Crash which I hadn't thought about in years.

I was thinking it was a deleted chapter written by Douglas Adams.

I wonder how many realize that you've described the life and many possible deaths of a packet. :-)

Across millions of deliveries, I'm sure there are some failures from time to time. I'm guessing Domino's has at-most-once semantics.

And then reconsider this at "webscale" (and yeah, I hate myself a little bit for using that term).

"Millions of deliveries" with a "five or six nines" 99.999% or 99.9999% success rate would almost certainly be considered spectacularly successful by Domino's. Wikipedia says $1.8billion in revenue, 220,000 employees, and 10,000 stores - some outrageous assumptions might be made. Lets say ~$500 per day per store is, what, a 15% of revenue franchise fee as a guess? So a store on average makes $3-4k/day? So maybe 3 to 4 hundred pizzas a day, right? Five nines would be one error per store per year. Six nines would be one error per store per _decade_. I bet their real-life error rate is _way_ worse than that.

But, across 10000 stores and 220,000 employees, a billion or so pizzas a year isn't really a very big number.

Now consider Google, or Facebook, or Amazon. How many emails/adviews/status-updates/likes/widget-orders do you suppose happen every hour? Would it be as low as 1 billion per hour? And would a spectacular seeming "six nines" of reliability, which means dropping a thousand mails/adviews/updates/orders _per hour_ be acceptable?

"failures from time to time" in some contexts, can mean "fundamentally and irrevocably broken" in other contexts...

Nah, it's at-least-once. For undelivered pizza you request a retransmit. I've seen people get duplicate packets if they requested a retransmit too early.

That reminds me of thing I heard many years ago: "And now look at Czech Post, it's obviously more reliable than internet. They can deliver letters with unbounded latency, letters could be delivered out of order, letters can get lost, but no mater what they do they are not able to deliver one letter twice"

On the other hand, after few years on various logistics-related projects, I would not be too surprised if there is some postal service or carrier that is actually able to somehow physically duplicate one shipment and deliver it twice :)

Oh, that happened to me few weeks ago. Ordered a pizza, received it and 10 minutes later another delivery person showed up with another pizza -- with the same order# on receipt!

More than once delivery in real-life :)

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