[Bitcoin-development] Increasing the OP_RETURN maximum payload size

Btc Drak btcdrak at gmail.com
Tue Nov 18 17:47:05 UTC 2014

On Mon, Nov 17, 2014 at 11:43 AM, Flavien Charlon <
flavien.charlon at coinprism.com> wrote:

> > My main concern with OP_RETURN is that it seems to encourage people to
> use the blockchain as a convenient transport channel
> The number one user of the blockchain as a storage and transport mechanism
> is Counterparty, and limiting OP_RETURN to 40 bytes didn't prevent them
> from doing so. In fact they use multi-sig outputs which is worse than
> OP_RETURN since it's not always prunable, and yet let them store much more
> than 40 bytes.
> For Open Assets <https://github.com/OpenAssets/open-assets-protocol>, we
> need to store a URL in the OP_RETURN output (with optionally a hash) plus
> some bytes of overhead. 40 bytes comes really short for that. The benefit
> of having a URL in there is that any storage mechanism can be used (Web,
> FTP, BitTorrent, MaidSafe...), whereas with only a hash, you have to
> hardcode the storing mechanism in the protocol (and even then, a hash is
> not enough to address a HTTP or FTP resource). Storing only a hash is fine
> for the most basic timestamping application, but it's hardly enough to
> build something interesting.
> I've counted the number of OP_RETURN outputs in the blockchain for the
> month of October 2014. There were 1,674 OP_RETURNs for a span of 4,659
> blocks. Assuming they were all 40 bytes (the average is probably less than
> half of that), that means an increase of 14.37 bytes per block. Considering
> a 1 MB block, that's about 0.0013% of the block used up by OP_RETURN data
> in average.
> Increasing to 80 bytes will have a negligible impact on bandwidth and
> storage requirements, while being extremely useful for many use cases where
> a hash only is not enough.

While I am not opposing the proposal, I am not sure about your statistics
because while Counterparty is not currently using OP_RETURN encoding, you
should factor in the number of CP transactions that would have been
OP_RETURNs if they had been permitted (100,000 since inception according
their blog[1] with monthly charts at their block explorer[2]).

[2] http://blockscan.com/
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