Hello HN,I enjoy reading about various companies' system architecture. I found some architectures, like WhatsApp, are very easy to find info about.  I haven't been able to find out a lot about Ebay's bid architecture.This is interesting to me because of a few things.
 - Many users are bidding on the same item and could put in the same bid at the same time.  So how do we resolve that?- Bids change very quickly particularly during the end of an auction.  How to quickly display the current bid to a lot of users.  Is that latest bid info contained in RDMS or cache?
 - How does the system validate a bid. For example at the time a user places a bid the price could be $99.25 and the user places a bid of $99.75, but by the time that users reaches the system the price has risen to $100.My Googling hasn't lead me to a satisfactory answer and I am hoping someone can point me in the right direction.Thanks