[bitcoin-dev] BIP 102 - kick the can down the road to 2MB

[Ross Nicoll]

Not so much that the implementation is difficult, as it requires context 
to validate a block size, rather than being able to validate it without 
requiring the preceeding blocks. Yes, time on different machines may 
vary, but block time is safe to use for this, because it's a 
straight-forward test of "if block time is acceptable and block time is 
after <date> then maximum block size allowed is n MB otherwise m MB".

Ross

On 21/07/2015 10:26, Jorge Timón wrote:
> I still disagree. Using height instead of time may make the
> implementation more complex by requiring some additional preparations
> but using height is in fact a simpler design. Why relay on clocks that
> we know will differ in different computers and places when we have a
> universal tick with every block?
>
> Btw, BIP16 and BIP34 could be changed to height-based activation
> already. BIP16 simply should have used height instead of time from the
> beginning.
>
> On Mon, Jul 20, 2015 at 12:51 AM, Ross Nicoll via bitcoin-dev
> <bitcoin-dev at lists.linuxfoundation.org> wrote:
>> Further to that - please disregard what I said about using block height. Had
>> failed to realise that in using contextual information (block height) it
>> complicates block validation (i.e. it would be impossible to tell if a block
>> is too big, without having all previous blocks first). Block time is in fact
>> the better option.
>>
>> Ross
>>
>>
>> On 17/07/2015 18:57, Ross Nicoll via bitcoin-dev wrote:
>>
>> I'd back this if we can't find a permanent solution - 2MB gives us a lot
>> more wiggle room in the interim at least; one of my concerns with block size
>> is 3 transactions per second is absolutely tiny, and we need space for the
>> network to search for an equilibrium between volume and pricing without risk
>> of an adoption spike rendering it essentially unusable.
>>
>> I'd favour switching over by block height rather than time, and I'd suggest
>> that given virtually every wallet/node out there will require testing (even
>> if many do not currently enforce a limit and therefore do not need
>> changing), 6 months should be considered a minimum target. I'd open with a
>> suggestion of block 390k as a target.
>>
>> Ross
>>
>> On 17/07/2015 16:55, Jeff Garzik via bitcoin-dev wrote:
>>
>> Opening a mailing list thread on this BIP:
>>
>> BIP PR: https://github.com/bitcoin/bips/pull/173
>> Code PR: https://github.com/bitcoin/bitcoin/pull/6451
>>
>> The general intent of this BIP is as a minimum viable alternative plan to my
>> preferred proposal (BIP 100).
>>
>> If agreement is not reached on a more comprehensive solution, then this
>> solution is at least available and a known quantity.  A good backup plan.
>>
>> Benefits:  conservative increase.  proves network can upgrade.  permits some
>> added growth, while the community & market gathers data on how an increased
>> block size impacts privacy, security, centralization, transaction throughput
>> and other metrics.  2MB seems to be a Least Common Denominator on an
>> increase.
>>
>> Costs:  requires a hard fork.  requires another hard fork down the road.
>>
>>
>>
>>
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