{"type":"rich","version":"1.0","author_name":"npub10r9d6edmnrljk59wsf06zqp494l3qtjpa3w245hy6t5euqxlzw2qdkgk2d","author_url":"https://nostr.ae/npub10r9d6edmnrljk59wsf06zqp494l3qtjpa3w245hy6t5euqxlzw2qdkgk2d","provider_name":"njump","provider_url":"https://nostr.ae","html":"📅 Original date posted:2017-05-09\n📝 Original message:The discount is designed to reduce UTXO bloat primarily, witness spam\ndata would not make it into the UTXO set. The discount brings the fee\nof a transaction more in line with the actual costs to the network for\nthe transaction. A miner spamming the network with 4MB witness blocks\nwould have very little impact on the UTXO size compared with 1MB\nnon-witness blocks. UTXO size is a bigger issue than blockchain size\nsince full nodes can't prune the UTXO set.\n\nThe discount of 75% for the SegWit softfork doesn't really have any\neffect on future hard forks as it can always be adjusted as needed\nlater on as part of a HF.\n\nOn Tue, May 9, 2017 at 8:49 AM, Sergio Demian Lerner via bitcoin-dev\n\u003cbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e This [1] article says the current discount prevents witness spam. Witness\n\u003e spam is free space in the witness part of the block that can be filled by\n\u003e miners to create bigger blocks with almost no cost for the benefit a cluster\n\u003e of miners with low latency, increasing centralization.\n\u003e\n\u003e The 75% discount does not prevent it, but on the contrary leaves a lot of\n\u003e extra witness space for spam.\n\u003e\n\u003e If the maximum block weight is set to 2.7M, each byte of non-witness block\n\u003e costs 1.7, and each byte of witness costs 1, then a normal filled block\n\u003e would be 2.7M bytes (1.7+1), and there will be no need to create ever a 4\n\u003e Mbyte block. The worst case would be the average case, and the transaction\n\u003e rate would be the maximum possible.\n\u003e\n\u003e The current 75% discount can only achieve more transactions per second if\n\u003e the type of transactions change. Therefore the current 75% discount only\n\u003e makes the block size worst case worse (4 Mbytes when it should be 2.7\n\u003e Mbytes).\n\u003e\n\u003e 80% of all inputs/outputs are P2PKH. The only way to make use of the extra\n\u003e witness\n\u003e space If most P2PKH transactions are replaced by multisigs (typically for\n\u003e LN).\n\u003e\n\u003e So it seems the 75% discount has been chosen with the idea that in the\n\u003e future the current transaction pattern will shift towards multisigs. This is\n\u003e not a bad idea, as it's the only direction Bitcoin can scale without a HF.\n\u003e But it's a bad idea if we end up doing, for example, a 2X blocksize increase\n\u003e HF in the future. In that case it's much better to use a 50% witness\n\u003e discount, and do not make scaling risky by making the worse case block size\n\u003e 8 Mbytes, when it could have been 2*2.7=5.4 Mbytes.\n\u003e\n\u003e I've uploaded the code here:\n\u003e https://github.com/SergioDemianLerner/SegwitStats\n\u003e\n\u003e  [1]\n\u003e https://segwit.org/why-a-discount-factor-of-4-why-not-2-or-8-bbcebe91721e.\n\u003e\n\u003e\n\u003e On Mon, May 8, 2017 at 8:47 PM, Alphonse Pace via bitcoin-dev\n\u003e \u003cbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e\u003e\n\u003e\u003e Sergio,\n\u003e\u003e\n\u003e\u003e I'm not sure what the data you present has to do with the discount.  A 75%\n\u003e\u003e discount prevents witness spam precisely because it is 75%, nothing more.\n\u003e\u003e The current usage simply gives a guideline on how much capacity is gained\n\u003e\u003e through a particular discount.  With the data you show, it would imply that\n\u003e\u003e those blocks, with SegWit used where possible, would result in blocks of\n\u003e\u003e ~1.8MB.\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e On Mon, May 8, 2017 at 5:42 PM, Sergio Demian Lerner via bitcoin-dev\n\u003e\u003e \u003cbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e\u003e\u003e\n\u003e\u003e\u003e I have processed 1000 blocks starting from Block #461653.\n\u003e\u003e\u003e\n\u003e\u003e\u003e I computed several metrics, including the supposed size of witness data\n\u003e\u003e\u003e and non-witness data (onchain), assuming all P2SH inputs/outputs are\n\u003e\u003e\u003e converted to P2PWSH and all P2PKH inputs/outputs are converted to P2WPKH.\n\u003e\u003e\u003e\n\u003e\u003e\u003e This takes into account that other types of transactions will not be\n\u003e\u003e\u003e modified by Segwit (e.g. OP_RETURN outputs, or P2PK). This analysis doesn't\n\u003e\u003e\u003e take into account that LN transactions may affect the current state,\n\u003e\u003e\u003e increasing the segwit/nosegwit ratio.\n\u003e\u003e\u003e\n\u003e\u003e\u003e Among a lot of information, I've got the following real world results...\n\u003e\u003e\u003e\n\u003e\u003e\u003e acMainChainSpace =352608924\n\u003e\u003e\u003e acSegwitSpace =599400403\n\u003e\u003e\u003e Ratio segwit/nosegwit=1.6999\n\u003e\u003e\u003e\n\u003e\u003e\u003e This implies that the 75% that discount is not the best option to prevent\n\u003e\u003e\u003e witness spam in a block of 4 MB, as stated in\n\u003e\u003e\u003e https://segwit.org/why-a-discount-factor-of-4-why-not-2-or-8-bbcebe91721e.\n\u003e\u003e\u003e\n\u003e\u003e\u003e The non-witness data weight factor should not be 4 but 2.35. The closest\n\u003e\u003e\u003e integer value is 2, which leads to a 50% witness discount.\n\u003e\u003e\u003e\n\u003e\u003e\u003e The Bitcoinj source code is available for anyone to review. I encourage\n\u003e\u003e\u003e anyone to re-compute this with another utility to cross-check. Maybe Antoine\n\u003e\u003e\u003e Le Calvez (p2sh.info) would like to double-check.\n\u003e\u003e\u003e\n\u003e\u003e\u003e\n\u003e\u003e\u003e\n\u003e\u003e\u003e\n\u003e\u003e\u003e\n\u003e\u003e\u003e\n\u003e\u003e\u003e _______________________________________________\n\u003e\u003e\u003e bitcoin-dev mailing list\n\u003e\u003e\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e\u003e\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\u003e\u003e\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e _______________________________________________\n\u003e\u003e bitcoin-dev mailing list\n\u003e\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\u003e\n\u003e\n\u003e\n\u003e _______________________________________________\n\u003e bitcoin-dev mailing list\n\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e"}