Subject: Re: [bitcoin-dev] Rolling UTXO set hashes

From: ZmnSCPxj <[email-masked]>
Date: Mon, 15 May 2017 19:04:01 -0400

Good morning Pieter,

>4. Use cases
>
>* Replacement for Bitcoin Core's gettxoutsetinfo RPC's hash
>computation. This currently requires minutes of I/O and CPU, as it
>serializes and hashes the entire UTXO set. A rolling set hash would
>make this instant, making the whole RPC much more usable for sanity
>checking.
>* Assisting in implementation of fast sync methods with known good
>blocks/UTXO sets.
>* Database consistency checking: by remembering the UTXO set hash of
>the past few blocks (computed on the fly), a consistency check can be
>done that recomputes it based on the database.

Another use case I can think of is a potential "chain-flip" hard fork of block header formats, where the UTXO hash rather than merkle tree root of transactions is in the header, which would let lite nodes download a UTXO set from any full node and verify it by verifying only block headers starting from genesis.

Regards,
ZmnSCPxj