Blockchain State Expiry: A Necessary Evolution for Scalability
Blockchain networks are facing a fundamental issue - they can't store everything forever. The more data that's stored, the heavier nodes become, and fewer people can run them. Fees reflect this pressure, leading to a point where the network has to say no.
This is where 'state expiry' comes in, not as a silver bullet or an overnight switch, but rather a set of strategies that prioritize keeping essential data accessible while allowing less important information to expire. State growth is compounding, with weekly new Ethereum state rising from 105 MiB to ~326 MiB after gas limit increases, representing about 116 GiB more state pressure per year.
Expiry and history pruning are different goals, with expiry targeting long-lived account and storage entries, while history pruning drops old block bodies and receipts. Tiering helps today, with a prototype showing around 58% of trie nodes moved cold and an observed ~21.6% total storage reduction.