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From: Luke Dashjr <luke@dashjr.org>
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Subject: Re: [bitcoin-dev] A Segwit2x BIP
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> Maximum transaction size is kept, to maximize compatibility with current
> software and prevent algorithmic and data size DoS's.
IIRC, it is actually increased by ~81 bytes, and doesn't count witness data if
on Segwit transactions (so in effect, nearly 4 MB transactions are possible).
This probably doesn't make the hashing problem worse, however it should be
made clear in the BIP.
> Assuming the current transaction pattern is replicated in a 2 MB
> plain-sized block that is 100% filled with transactions, then the
> witness-serialized block would occupy 3.6 MB [1]. This is considered safe
> by many users, companies, miners and academics [2].
Citations do not support the claim.
> The plain block size is defined as the serialized block size without
> witness programs.
This is deceptive and meaningless. There is no reason to *ever* refer to the
size of the block serialised without witness programs. It is not a meaningful
number.
> Deploy a modified BIP91 to activate Segwit. The only modification is that
> the signal "segsignal" is replaced by "segwit2x".
What is modified here? "segsignal" does not appear in the BIP 91 protocol at
all...
> If segwit2x (BIP91 signal) activates at block N, then block N+12960
> activates a new plain block size limit of 2 MB (2,000,000 bytes). In this
> case, at block N+12960 a hard-fork occurs.
A "plain block size limit" of 2 MB would be a no-op. It would have literally
no effect whatsoever on the network rules.
Furthermore, this does not match what btc1/Segwit2x currently implements at
all. The actual implementation is: If Segwit (via deployment method) activates
at block N, then block N+12960 activates a new weight limit of 8M (which
corresponds to a size of up to 8,000,000 bytes).
> Any transaction with a non-witness serialized size exceeding 1,000,000 is
> invalid.
What is the rationale for excluding witness data from this measurement?
> In the short term, an increase is needed to continue to facilitate network
> growth, and buy time...
Actual network growth does not reflect a pattern that supports this claim.
> This reduces the fee pressure on users and companies creating on-chain
> transactions, matching market expectations and preventing further market
> disruption.
Larger block sizes is not likely to have a meaningful impact on fee pressure.
Any expectations that do not match the reality are merely misguided, and
should not be a basis for changing Bitcoin.
Luke
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