[arter45]

A great lesson for system design job interviews - if this is a popular payment system in a country with 1.5 billion people, your theoretical system you're designing for a small company cargo culting Google interviews will not likely support millions or even tens of thousands of average TPS.

[inigyou]

Well, they are money-moving transactions which means each person only does them a few times per day. If your system's transactions are more like showing the weather on the home screen, it's plausible you could have orders of magnitude more traffic than a payment system.

[AugustoCAS]

To add - I agree that payments is great question for systems designs.

Merchants need to receive the money and being able to transact with it. Imagine the merchant receiving the payment is something like Amazon or Ebay (sorry, I don't know what similar large online retailers are in India).

With the above, the problem becomes harder. Imagine receiving 2-3k TPS just on one account during a black Friday or similar day.

Now your system has to perform fine for accounts that do 30 transactions an hour for a retail customer and 3k a second for a merchant.