Re: [bitcoin-dev] Hypothetical 2 MB hardfork to follow BIP148

[Luke Dashjr <luke@dashjr.org>]

On Wednesday 31 May 2017 1:22:44 AM Jorge Timón via bitcoin-dev wrote:
> Why is it
> https://github.com/bitcoin/bitcoin/blob/master/src/validation.cpp#L1661
> not enough at this point?
> Why the need for a transaction size limit?

Because the bottleneck is hashing the transaction, which costs (in CPU time) 
based on its size. Maybe it would make sense to factor sigops into the limit, 
though?

On Wednesday 31 May 2017 1:09:26 AM Jean-Paul Kogelman via bitcoin-dev wrote:
> On May 30, 2017, at 4:50 PM, James MacWhyte wrote:
> > Add a transaction-size limit of, say, 10kb and the quadratic hashing
> > problem is a non-issue. Donezo.
>
> That would invalidate any pre-signed transactions that are currently out
> there. You can't just change the rules out from under people.

Make it 100kB and I think we'd be okay. Those have always been policy-
forbidden so there should be no expectation they'd be acceptable in the 
future.

While we're at it, I suggest also specifying a minimum transaction size as 
well. The raw minimum possible is 60 bytes, but any sane output would need at 
least a hash, so I'd say make the minimum be 8 (60 + 160-bit hash) bytes?

Luke