Compact Blocks

• From a paper (Summer 2019) by Andrew Poelstra (Blockstream) and David Vorick (Sia):

"When you see a block and everything was previously validated, then you don't need to validate them. With compact blocks, you don't even need to download the transaction. You get a summary of the block contents and you're able to quickly tell oh this summary only contains things that I know about and this block is good.

We've talked about compact blocks and FIBRE. People sometimes get this confused. Compact blocks is about propagating blocks to nodes in the hopes that they already have the transaction. FIBRE is about miners communicating blocks to each other, and its goal is to minimize latency. Miners learn new blocks as quickly as possible. FIBRE is super wasteful at bandwidth. It uses an error correcting code to blindly send it among as many paths as it can to sort of stream the data. As long as it sees as much data from many different nodes, it can reconstruct that block basically. So one is for nodes, one is for miners."