Subject: Re: [bitcoin-dev] Covenants and capabilities in the UTXO model

From: Peter Todd <[email-masked]>
Date: Thu, 20 Jan 2022 21:22:15 -0500

On Thu, Jan 20, 2022 at 11:23:30AM -0800, Bram Cohen via bitcoin-dev wrote:
> > Nodes currently aren't required to keep around the whole blockchain, but
> > your proposal sounds like it would require them to. I think this could be
> > pretty detrimental to future scalability. Monero, for example, has a
> > situation where its UTXO set is the whole blockchain because you can't
> > generally know what has been spent and what hasn't been. Allowing
> > references to old blocks would pull in all this old block data into the
> > UTXO set. So unless you're very careful about how or when you can reference
> > old blocks, this could cause issues.
> >
> 
> Don't full nodes by definition have to have the whole chain? This does make
> pruned nodes difficult, but it could also have rules like you can only
> point back so far.

"you can only point back so far" leads to transactions becoming invalid, which
is something we've always strictly avoided because it can result in huge
problems during reorgs with transactions being unable to be included in a new
change. That's exactly why transaction expiry proposals have been shot down
over and over again.

-- 
https://petertodd.org 'peter'[:-1]@petertodd.org