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July 21, 2015, 10:54:31 AM Last edit: July 21, 2015, 02:51:14 PM by jl2012 |
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There are some ways to limit the growth of UTXO set:
1. Discouraging creation of new UTXO --- fee and relay rules
2. Encouraging consumption of UTXO --- fee reduction and relay rules
3. Limit the delta-UTXO-size for each block --- softfork/hardfork
However, some small UTXOs may never be economic to spend, or the private keys are simply lost. I bet this is not a new idea but I think we should consider to delete those "abandoned" UTXOs.
That would be too controversial if we are trying to delete any existing UTXOs. Therefore, this proposal applies only to new UTXOs.
This is a softfork:
1. 0-value outputs are not spendable
1a. (variation) 0-value outputs must be spent within 5,000,000s
2. An output of 1 satoshi must be spent within 10,000,000s (3.8 months) after it is created. The creation time and the deadline are both determined by the block timestamp.
3. As the value doubles, the deadline is extended by 10,000,000s. For example, with 1.34217728BTC (2^27), the UTXO can stay untouched for 280,000,000s (8.87 years)
4. No interpolation: e.g., the deadline for 1.34217727BTC is 270,000,000s after creation. In practice, it just measures the length of value in binary with leading zeros removed, and multiplies the length with 10,000,000. The code should be simple.
5. Bitcoin in deleted UTXOs are lost permanently. Most commercial banks will just confiscate your money if the account is dormant for many (say 5) years. The blockchain bank, however, will just delete the record.
The initial value of 10,000,000s is chosen, so that assuming the extreme case of 1BTC = 1,000,000USD, an UTXO with 128 satoshi (1.28USD) will still have 2.5 years to spend. Anything with at least 327.68USD will have minimum 5 years of storage period.
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The arguments for this proposal are:
1. Limiting the growth of UTXO set.
2. No one should assume that other people would store data for free indefinitely.
3. Stabilizing Bitcoin's value if we could prove some bitcoins are really lost.
4. The original "Bitcoin contract" is not violated if the proposal is not applied to existing UTXOs
The arguments against this proposal are:
1. It opens a Pandora's box of confiscating bitcoin
2. It will create more on-chain transactions as people are forced to move their bitcoin. Enough block size is needed to make sure people will not lose bitcoin due to lack of block size.
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