* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-09 17:09 Jim Phillips
@ 2015-05-09 18:45 ` Peter Todd
2015-05-09 19:02 ` Jim Phillips
2015-05-09 19:00 ` Andreas Schildbach
` (5 subsequent siblings)
6 siblings, 1 reply; 32+ messages in thread
From: Peter Todd @ 2015-05-09 18:45 UTC (permalink / raw)
To: Jim Phillips; +Cc: bitcoin-development
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On Sat, May 09, 2015 at 12:09:32PM -0500, Jim Phillips wrote:
> The vast majority of users are running one of a handful of different wallet
> apps: Core, Electrum; Armory; Mycelium; Breadwallet; Coinbase; Circle;
> Blockchain.info; and maybe a few others. The developers of all these
> wallets have a vested interest in the continued usefulness of Bitcoin, and
> so should not be opposed to changing their UTXO selection algorithms to one
> that reduces the UTXO database instead of growing it.
You can't assume that UTXO growth will be driven by walles at all; the
UTXO set's global consensus functionality is incredibly useful and will
certainly be used by all manner of applications, many having nothing to
do with Bitcoin.
As one of many examples, here's a proposal - with working code - to use
the UTXO set to get consensus over TLC certificate revocations. The
author, Christopher Allen, was one of the co-authors of the SSL
standard:
https://github.com/ChristopherA/revocable-self-signed-tls-certificates-hack
There's nothing we can do to stop these kinds of usages other than
forcing users to identify themselves to get permission to use the
Bitcoin blockchain. Using the Bitcoin blockchain gives their users
significantly better security in many cases than any alternatives, so
there's strong incentives to do so. Finally, the cost many of these
alternative uses are willing to pay pre UTXO/transaction is
significantly higher than the fees many existing Bitcoin users can pay
to make transactions.
--
'peter'[:-1]@petertodd.org
00000000000000000e7980aab9c096c46e7f34c43a661c5cb2ea71525ebb8af7
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^ permalink raw reply [flat|nested] 32+ messages in thread* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-09 18:45 ` Peter Todd
@ 2015-05-09 19:02 ` Jim Phillips
0 siblings, 0 replies; 32+ messages in thread
From: Jim Phillips @ 2015-05-09 19:02 UTC (permalink / raw)
To: Peter Todd; +Cc: bitcoin-development
[-- Attachment #1: Type: text/plain, Size: 1741 bytes --]
On Sat, May 9, 2015 at 1:45 PM, Peter Todd <pete@petertodd•org> wrote:
> On Sat, May 09, 2015 at 12:09:32PM -0500, Jim Phillips wrote:
> > The vast majority of users are running one of a handful of different
> wallet
> > apps: Core, Electrum; Armory; Mycelium; Breadwallet; Coinbase; Circle;
> > Blockchain.info; and maybe a few others. The developers of all these
> > wallets have a vested interest in the continued usefulness of Bitcoin,
> and
> > so should not be opposed to changing their UTXO selection algorithms to
> one
> > that reduces the UTXO database instead of growing it.
>
> You can't assume that UTXO growth will be driven by walles at all; the
> UTXO set's global consensus functionality is incredibly useful and will
> certainly be used by all manner of applications, many having nothing to
> do with Bitcoin.
>
You're correct in this point. Future UTXO growth will be coming from all
directions. But I'm a believer in the idea that whatever can be done should
be done. If we get Bitcoin devs into the mindset now that UTXOs are
expensive to those that have to store them, and that they should be good
netizens and do what they can to limit them, then hopefully that will ideal
will be passed down to future developers. I don't believe consolidating
UTXOs in the wallet is the only solution.. I just think it is a fairly easy
one to implement, and can only help the problem from getting worse in the
future.
--
*James G. Phillips IV*
<https://plus.google.com/u/0/113107039501292625391/posts>
<http://www.linkedin.com/in/ergophobe>
*"Don't bunt. Aim out of the ball park. Aim for the company of immortals."
-- David Ogilvy*
*This message was created with 100% recycled electrons. Please think twice
before printing.*
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-09 17:09 Jim Phillips
2015-05-09 18:45 ` Peter Todd
@ 2015-05-09 19:00 ` Andreas Schildbach
2015-05-09 19:05 ` Jim Phillips
2015-05-09 19:06 ` Pieter Wuille
[not found] ` <3862E01F-FD0F-48F5-A6D9-F8E0FB0AB68F@newcastle.ac.uk>
` (4 subsequent siblings)
6 siblings, 2 replies; 32+ messages in thread
From: Andreas Schildbach @ 2015-05-09 19:00 UTC (permalink / raw)
To: bitcoin-development
Actually your assumption is wrong. Bitcoin Wallet (and I think most, if
not all, other bitcoinj based wallets) picks UTXO by age, in order to
maximize priority. So it keeps the number of UTXOs low, though not as
low as if it would always pick *all* UTXOs.
On 05/09/2015 07:09 PM, Jim Phillips wrote:
> Forgive me if this idea has been suggested before, but I made this
> suggestion on reddit and I got some feedback recommending I also bring
> it to this list -- so here goes.
>
> I wonder if there isn't perhaps a simpler way of dealing with UTXO
> growth. What if, rather than deal with the issue at the protocol level,
> we deal with it at the source of the problem -- the wallets. Right now,
> the typical wallet selects only the minimum number of unspent outputs
> when building a transaction. The goal is to keep the transaction size to
> a minimum so that the fee stays low. Consequently, lots of unspent
> outputs just don't get used, and are left lying around until some point
> in the future.
>
> What if we started designing wallets to consolidate unspent outputs?
> When selecting unspent outputs for a transaction, rather than choosing
> just the minimum number from a particular address, why not select them
> ALL? Take all of the UTXOs from a particular address or wallet, send
> however much needs to be spent to the payee, and send the rest back to
> the same address or a change address as a single output? Through this
> method, we should wind up shrinking the UTXO database over time rather
> than growing it with each transaction. Obviously, as Bitcoin gains wider
> adoption, the UTXO database will grow, simply because there are 7
> billion people in the world, and eventually a good percentage of them
> will have one or more wallets with spendable bitcoin. But this idea
> could limit the growth at least.
>
> The vast majority of users are running one of a handful of different
> wallet apps: Core, Electrum; Armory; Mycelium; Breadwallet; Coinbase;
> Circle; Blockchain.info; and maybe a few others. The developers of all
> these wallets have a vested interest in the continued usefulness of
> Bitcoin, and so should not be opposed to changing their UTXO selection
> algorithms to one that reduces the UTXO database instead of growing it.
>
> From the miners perspective, even though these types of transactions
> would be larger, the fee could stay low. Miners actually benefit from
> them in that it reduces the amount of storage they need to dedicate to
> holding the UTXO. So miners are incentivized to mine these types of
> transactions with a higher priority despite a low fee.
>
> Relays could also get in on the action and enforce this type of behavior
> by refusing to relay or deprioritizing the relay of transactions that
> don't use all of the available UTXOs from the addresses used as inputs.
> Relays are not only the ones who benefit the most from a reduction of
> the UTXO database, they're also in the best position to promote good
> behavior.
>
> --
> *James G. Phillips
> IV* <https://plus.google.com/u/0/113107039501292625391/posts>
> /"Don't bunt. Aim out of the ball park. Aim for the company of
> immortals." -- David Ogilvy
> /
>
> /This message was created with 100% recycled electrons. Please think
> twice before printing./
>
>
> ------------------------------------------------------------------------------
> One dashboard for servers and applications across Physical-Virtual-Cloud
> Widest out-of-the-box monitoring support with 50+ applications
> Performance metrics, stats and reports that give you Actionable Insights
> Deep dive visibility with transaction tracing using APM Insight.
> http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
>
>
>
> _______________________________________________
> Bitcoin-development mailing list
> Bitcoin-development@lists•sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>
^ permalink raw reply [flat|nested] 32+ messages in thread* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-09 19:00 ` Andreas Schildbach
@ 2015-05-09 19:05 ` Jim Phillips
2015-05-09 19:06 ` Pieter Wuille
1 sibling, 0 replies; 32+ messages in thread
From: Jim Phillips @ 2015-05-09 19:05 UTC (permalink / raw)
To: Andreas Schildbach; +Cc: bitcoin-development
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On Sat, May 9, 2015 at 2:00 PM, Andreas Schildbach <andreas@schildbach•de>
wrote:
> Actually your assumption is wrong. Bitcoin Wallet (and I think most, if
> not all, other bitcoinj based wallets) picks UTXO by age, in order to
> maximize priority. So it keeps the number of UTXOs low, though not as
> low as if it would always pick *all* UTXOs.
>
> Is it not fair to say though that UTXO database growth is not considered
when selecting the UTXOs to use? And that size of transaction is a priority
if not the top priority?
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-09 19:00 ` Andreas Schildbach
2015-05-09 19:05 ` Jim Phillips
@ 2015-05-09 19:06 ` Pieter Wuille
2015-05-09 19:16 ` Jim Phillips
1 sibling, 1 reply; 32+ messages in thread
From: Pieter Wuille @ 2015-05-09 19:06 UTC (permalink / raw)
To: Andreas Schildbach; +Cc: Bitcoin Dev
[-- Attachment #1: Type: text/plain, Size: 5168 bytes --]
It's a very complex trade-off, which is hard to optimize for all use cases.
Using more UTXOs requires larger transactions, and thus more fees in
general. In addition, it results in more linkage between coins/addresses
used, so lower privacy.
The only way you can guarantee an economical reason to keep the UTXO set
small is by actually having a consensus rule that punishes increasing its
size.
On May 9, 2015 12:02 PM, "Andreas Schildbach" <andreas@schildbach•de> wrote:
> Actually your assumption is wrong. Bitcoin Wallet (and I think most, if
> not all, other bitcoinj based wallets) picks UTXO by age, in order to
> maximize priority. So it keeps the number of UTXOs low, though not as
> low as if it would always pick *all* UTXOs.
>
>
> On 05/09/2015 07:09 PM, Jim Phillips wrote:
> > Forgive me if this idea has been suggested before, but I made this
> > suggestion on reddit and I got some feedback recommending I also bring
> > it to this list -- so here goes.
> >
> > I wonder if there isn't perhaps a simpler way of dealing with UTXO
> > growth. What if, rather than deal with the issue at the protocol level,
> > we deal with it at the source of the problem -- the wallets. Right now,
> > the typical wallet selects only the minimum number of unspent outputs
> > when building a transaction. The goal is to keep the transaction size to
> > a minimum so that the fee stays low. Consequently, lots of unspent
> > outputs just don't get used, and are left lying around until some point
> > in the future.
> >
> > What if we started designing wallets to consolidate unspent outputs?
> > When selecting unspent outputs for a transaction, rather than choosing
> > just the minimum number from a particular address, why not select them
> > ALL? Take all of the UTXOs from a particular address or wallet, send
> > however much needs to be spent to the payee, and send the rest back to
> > the same address or a change address as a single output? Through this
> > method, we should wind up shrinking the UTXO database over time rather
> > than growing it with each transaction. Obviously, as Bitcoin gains wider
> > adoption, the UTXO database will grow, simply because there are 7
> > billion people in the world, and eventually a good percentage of them
> > will have one or more wallets with spendable bitcoin. But this idea
> > could limit the growth at least.
> >
> > The vast majority of users are running one of a handful of different
> > wallet apps: Core, Electrum; Armory; Mycelium; Breadwallet; Coinbase;
> > Circle; Blockchain.info; and maybe a few others. The developers of all
> > these wallets have a vested interest in the continued usefulness of
> > Bitcoin, and so should not be opposed to changing their UTXO selection
> > algorithms to one that reduces the UTXO database instead of growing it.
> >
> > From the miners perspective, even though these types of transactions
> > would be larger, the fee could stay low. Miners actually benefit from
> > them in that it reduces the amount of storage they need to dedicate to
> > holding the UTXO. So miners are incentivized to mine these types of
> > transactions with a higher priority despite a low fee.
> >
> > Relays could also get in on the action and enforce this type of behavior
> > by refusing to relay or deprioritizing the relay of transactions that
> > don't use all of the available UTXOs from the addresses used as inputs.
> > Relays are not only the ones who benefit the most from a reduction of
> > the UTXO database, they're also in the best position to promote good
> > behavior.
> >
> > --
> > *James G. Phillips
> > IV* <https://plus.google.com/u/0/113107039501292625391/posts>
> > /"Don't bunt. Aim out of the ball park. Aim for the company of
> > immortals." -- David Ogilvy
> > /
> >
> > /This message was created with 100% recycled electrons. Please think
> > twice before printing./
> >
> >
> >
> ------------------------------------------------------------------------------
> > One dashboard for servers and applications across Physical-Virtual-Cloud
> > Widest out-of-the-box monitoring support with 50+ applications
> > Performance metrics, stats and reports that give you Actionable Insights
> > Deep dive visibility with transaction tracing using APM Insight.
> > http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
> >
> >
> >
> > _______________________________________________
> > Bitcoin-development mailing list
> > Bitcoin-development@lists•sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/bitcoin-development
> >
>
>
>
>
> ------------------------------------------------------------------------------
> One dashboard for servers and applications across Physical-Virtual-Cloud
> Widest out-of-the-box monitoring support with 50+ applications
> Performance metrics, stats and reports that give you Actionable Insights
> Deep dive visibility with transaction tracing using APM Insight.
> http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
> _______________________________________________
> Bitcoin-development mailing list
> Bitcoin-development@lists•sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-09 19:06 ` Pieter Wuille
@ 2015-05-09 19:16 ` Jim Phillips
2015-05-09 19:43 ` Ross Nicoll
0 siblings, 1 reply; 32+ messages in thread
From: Jim Phillips @ 2015-05-09 19:16 UTC (permalink / raw)
To: Pieter Wuille; +Cc: Bitcoin Dev, Andreas Schildbach
[-- Attachment #1: Type: text/plain, Size: 1325 bytes --]
On Sat, May 9, 2015 at 2:06 PM, Pieter Wuille <pieter.wuille@gmail•com>
wrote:
> It's a very complex trade-off, which is hard to optimize for all use
> cases. Using more UTXOs requires larger transactions, and thus more fees in
> general.
>
Unless the miner determines that the reduction in UTXO storage requirements
is worth the lower fee. There's no protocol level enforcement of a fee as
far as I understand it. It's enforced by the miners and their willingness
to include a transaction in a block.
> In addition, it results in more linkage between coins/addresses used, so
> lower privacy.
>
Not if you only select all the UTXOs from a single address. A wallet that
is geared more towards privacy minded individuals may want to reduce the
amount of address linkage, but a wallet geared towards the general masses
probably won't have to worry so much about that.
> The only way you can guarantee an economical reason to keep the UTXO set
> small is by actually having a consensus rule that punishes increasing its
> size.
>
There's an economical reason right now to keeping the UTXO set small. The
smaller it is, the easier it is for the individual to run a full node. The
easier it is to run a full node, the faster Bitcoin will spread to the
masses. The faster it spreads to the masses, the more valuable it becomes.
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-09 19:16 ` Jim Phillips
@ 2015-05-09 19:43 ` Ross Nicoll
0 siblings, 0 replies; 32+ messages in thread
From: Ross Nicoll @ 2015-05-09 19:43 UTC (permalink / raw)
To: Jim Phillips, Pieter Wuille; +Cc: Bitcoin Dev, Andreas Schildbach
[-- Attachment #1: Type: text/plain, Size: 2438 bytes --]
I think potential fee subsidies for cleaning up UTXO (and/or penalties
for creating more UTXO than you burn) are worth thinking about. As
Gavin's post ( gavinandresen.ninja/utxo-uhoh ) indicates, UTXO cost is
far higher than block storage, so charging differently for the in/out
mismatches should make good economic sense.
Ross
On 09/05/2015 20:16, Jim Phillips wrote:
> On Sat, May 9, 2015 at 2:06 PM, Pieter Wuille <pieter.wuille@gmail•com
> <mailto:pieter.wuille@gmail•com>> wrote:
>
> It's a very complex trade-off, which is hard to optimize for all
> use cases. Using more UTXOs requires larger transactions, and thus
> more fees in general.
>
> Unless the miner determines that the reduction in UTXO storage
> requirements is worth the lower fee. There's no protocol level
> enforcement of a fee as far as I understand it. It's enforced by the
> miners and their willingness to include a transaction in a block.
>
> In addition, it results in more linkage between coins/addresses
> used, so lower privacy.
>
> Not if you only select all the UTXOs from a single address. A wallet
> that is geared more towards privacy minded individuals may want to
> reduce the amount of address linkage, but a wallet geared towards the
> general masses probably won't have to worry so much about that.
>
> The only way you can guarantee an economical reason to keep the
> UTXO set small is by actually having a consensus rule that
> punishes increasing its size.
>
> There's an economical reason right now to keeping the UTXO set small.
> The smaller it is, the easier it is for the individual to run a full
> node. The easier it is to run a full node, the faster Bitcoin will
> spread to the masses. The faster it spreads to the masses, the more
> valuable it becomes.
>
>
>
> ------------------------------------------------------------------------------
> One dashboard for servers and applications across Physical-Virtual-Cloud
> Widest out-of-the-box monitoring support with 50+ applications
> Performance metrics, stats and reports that give you Actionable Insights
> Deep dive visibility with transaction tracing using APM Insight.
> http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
>
>
> _______________________________________________
> Bitcoin-development mailing list
> Bitcoin-development@lists•sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
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^ permalink raw reply [flat|nested] 32+ messages in thread
[parent not found: <3862E01F-FD0F-48F5-A6D9-F8E0FB0AB68F@newcastle.ac.uk>]
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-09 17:09 Jim Phillips
` (2 preceding siblings ...)
[not found] ` <3862E01F-FD0F-48F5-A6D9-F8E0FB0AB68F@newcastle.ac.uk>
@ 2015-05-10 2:11 ` Matt Whitlock
2015-05-10 12:11 ` Jim Phillips
2015-05-25 18:41 ` Mike Hearn
2015-05-10 13:35 ` Bob McElrath
` (2 subsequent siblings)
6 siblings, 2 replies; 32+ messages in thread
From: Matt Whitlock @ 2015-05-10 2:11 UTC (permalink / raw)
To: bitcoin-development
Minimizing the number of UTXOs in a wallet is sometimes not in the best interests of the user. In fact, quite often I've wished for a configuration option like "Try to maintain _[number]_ UTXOs in the wallet." This is because I often want to make multiple spends from my wallet within one block, but spends of unconfirmed inputs are less reliable than spends of confirmed inputs, and some wallets (e.g., Andreas Schildbach's wallet) don't even allow it - you can only spend confirmed UTXOs. I can't tell you how aggravating it is to have to tell a friend, "Oh, oops, I can't pay you yet. I have to wait for the last transaction I did to confirm first." All the more aggravating because I know, if I have multiple UTXOs in my wallet, I can make multiple spends within the same block.
On Saturday, 9 May 2015, at 12:09 pm, Jim Phillips wrote:
> Forgive me if this idea has been suggested before, but I made this
> suggestion on reddit and I got some feedback recommending I also bring it
> to this list -- so here goes.
>
> I wonder if there isn't perhaps a simpler way of dealing with UTXO growth.
> What if, rather than deal with the issue at the protocol level, we deal
> with it at the source of the problem -- the wallets. Right now, the typical
> wallet selects only the minimum number of unspent outputs when building a
> transaction. The goal is to keep the transaction size to a minimum so that
> the fee stays low. Consequently, lots of unspent outputs just don't get
> used, and are left lying around until some point in the future.
>
> What if we started designing wallets to consolidate unspent outputs? When
> selecting unspent outputs for a transaction, rather than choosing just the
> minimum number from a particular address, why not select them ALL? Take all
> of the UTXOs from a particular address or wallet, send however much needs
> to be spent to the payee, and send the rest back to the same address or a
> change address as a single output? Through this method, we should wind up
> shrinking the UTXO database over time rather than growing it with each
> transaction. Obviously, as Bitcoin gains wider adoption, the UTXO database
> will grow, simply because there are 7 billion people in the world, and
> eventually a good percentage of them will have one or more wallets with
> spendable bitcoin. But this idea could limit the growth at least.
>
> The vast majority of users are running one of a handful of different wallet
> apps: Core, Electrum; Armory; Mycelium; Breadwallet; Coinbase; Circle;
> Blockchain.info; and maybe a few others. The developers of all these
> wallets have a vested interest in the continued usefulness of Bitcoin, and
> so should not be opposed to changing their UTXO selection algorithms to one
> that reduces the UTXO database instead of growing it.
>
> >From the miners perspective, even though these types of transactions would
> be larger, the fee could stay low. Miners actually benefit from them in
> that it reduces the amount of storage they need to dedicate to holding the
> UTXO. So miners are incentivized to mine these types of transactions with a
> higher priority despite a low fee.
>
> Relays could also get in on the action and enforce this type of behavior by
> refusing to relay or deprioritizing the relay of transactions that don't
> use all of the available UTXOs from the addresses used as inputs. Relays
> are not only the ones who benefit the most from a reduction of the UTXO
> database, they're also in the best position to promote good behavior.
>
> --
> *James G. Phillips IV*
> <https://plus.google.com/u/0/113107039501292625391/posts>
>
> *"Don't bunt. Aim out of the ball park. Aim for the company of immortals."
> -- David Ogilvy*
>
> *This message was created with 100% recycled electrons. Please think twice
> before printing.*
^ permalink raw reply [flat|nested] 32+ messages in thread* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-10 2:11 ` Matt Whitlock
@ 2015-05-10 12:11 ` Jim Phillips
2015-05-25 18:41 ` Mike Hearn
1 sibling, 0 replies; 32+ messages in thread
From: Jim Phillips @ 2015-05-10 12:11 UTC (permalink / raw)
To: Matt Whitlock; +Cc: Bitcoin Dev
[-- Attachment #1: Type: text/plain, Size: 4363 bytes --]
I feel your pain. I've had the same thing happen to me in the past. And I
agree it's more likely to occur with my proposed scheme but I think with HD
wallets there will still be UTXOs left unspent after most transactions
since, for privacy sake it's looking for the smallest set of addresses that
can be linked.
On May 9, 2015 9:11 PM, "Matt Whitlock" <bip@mattwhitlock•name> wrote:
> Minimizing the number of UTXOs in a wallet is sometimes not in the best
> interests of the user. In fact, quite often I've wished for a configuration
> option like "Try to maintain _[number]_ UTXOs in the wallet." This is
> because I often want to make multiple spends from my wallet within one
> block, but spends of unconfirmed inputs are less reliable than spends of
> confirmed inputs, and some wallets (e.g., Andreas Schildbach's wallet)
> don't even allow it - you can only spend confirmed UTXOs. I can't tell you
> how aggravating it is to have to tell a friend, "Oh, oops, I can't pay you
> yet. I have to wait for the last transaction I did to confirm first." All
> the more aggravating because I know, if I have multiple UTXOs in my wallet,
> I can make multiple spends within the same block.
>
>
> On Saturday, 9 May 2015, at 12:09 pm, Jim Phillips wrote:
> > Forgive me if this idea has been suggested before, but I made this
> > suggestion on reddit and I got some feedback recommending I also bring it
> > to this list -- so here goes.
> >
> > I wonder if there isn't perhaps a simpler way of dealing with UTXO
> growth.
> > What if, rather than deal with the issue at the protocol level, we deal
> > with it at the source of the problem -- the wallets. Right now, the
> typical
> > wallet selects only the minimum number of unspent outputs when building a
> > transaction. The goal is to keep the transaction size to a minimum so
> that
> > the fee stays low. Consequently, lots of unspent outputs just don't get
> > used, and are left lying around until some point in the future.
> >
> > What if we started designing wallets to consolidate unspent outputs? When
> > selecting unspent outputs for a transaction, rather than choosing just
> the
> > minimum number from a particular address, why not select them ALL? Take
> all
> > of the UTXOs from a particular address or wallet, send however much needs
> > to be spent to the payee, and send the rest back to the same address or a
> > change address as a single output? Through this method, we should wind up
> > shrinking the UTXO database over time rather than growing it with each
> > transaction. Obviously, as Bitcoin gains wider adoption, the UTXO
> database
> > will grow, simply because there are 7 billion people in the world, and
> > eventually a good percentage of them will have one or more wallets with
> > spendable bitcoin. But this idea could limit the growth at least.
> >
> > The vast majority of users are running one of a handful of different
> wallet
> > apps: Core, Electrum; Armory; Mycelium; Breadwallet; Coinbase; Circle;
> > Blockchain.info; and maybe a few others. The developers of all these
> > wallets have a vested interest in the continued usefulness of Bitcoin,
> and
> > so should not be opposed to changing their UTXO selection algorithms to
> one
> > that reduces the UTXO database instead of growing it.
> >
> > >From the miners perspective, even though these types of transactions
> would
> > be larger, the fee could stay low. Miners actually benefit from them in
> > that it reduces the amount of storage they need to dedicate to holding
> the
> > UTXO. So miners are incentivized to mine these types of transactions
> with a
> > higher priority despite a low fee.
> >
> > Relays could also get in on the action and enforce this type of behavior
> by
> > refusing to relay or deprioritizing the relay of transactions that don't
> > use all of the available UTXOs from the addresses used as inputs. Relays
> > are not only the ones who benefit the most from a reduction of the UTXO
> > database, they're also in the best position to promote good behavior.
> >
> > --
> > *James G. Phillips IV*
> > <https://plus.google.com/u/0/113107039501292625391/posts>
> >
> > *"Don't bunt. Aim out of the ball park. Aim for the company of
> immortals."
> > -- David Ogilvy*
> >
> > *This message was created with 100% recycled electrons. Please think
> twice
> > before printing.*
>
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-10 2:11 ` Matt Whitlock
2015-05-10 12:11 ` Jim Phillips
@ 2015-05-25 18:41 ` Mike Hearn
2015-05-25 20:03 ` Matt Whitlock
1 sibling, 1 reply; 32+ messages in thread
From: Mike Hearn @ 2015-05-25 18:41 UTC (permalink / raw)
To: Matt Whitlock; +Cc: Bitcoin Dev
[-- Attachment #1: Type: text/plain, Size: 695 bytes --]
>
> some wallets (e.g., Andreas Schildbach's wallet) don't even allow it - you
> can only spend confirmed UTXOs. I can't tell you how aggravating it is to
> have to tell a friend, "Oh, oops, I can't pay you yet. I have to wait for
> the last transaction I did to confirm first." All the more aggravating
> because I know, if I have multiple UTXOs in my wallet, I can make multiple
> spends within the same block.
>
Andreas' wallet hasn't done that for years. Are you repeating this from
some very old memory or do you actually see this issue in reality?
The only time you're forced to wait for confirmations is when you have an
unconfirmed inbound transaction, and thus the sender is unknown.
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-25 18:41 ` Mike Hearn
@ 2015-05-25 20:03 ` Matt Whitlock
2015-05-25 20:29 ` Andreas Schildbach
2015-05-25 21:12 ` Mike Hearn
0 siblings, 2 replies; 32+ messages in thread
From: Matt Whitlock @ 2015-05-25 20:03 UTC (permalink / raw)
To: Mike Hearn; +Cc: Bitcoin Dev
On Monday, 25 May 2015, at 8:41 pm, Mike Hearn wrote:
> > some wallets (e.g., Andreas Schildbach's wallet) don't even allow it - you
> > can only spend confirmed UTXOs. I can't tell you how aggravating it is to
> > have to tell a friend, "Oh, oops, I can't pay you yet. I have to wait for
> > the last transaction I did to confirm first." All the more aggravating
> > because I know, if I have multiple UTXOs in my wallet, I can make multiple
> > spends within the same block.
>
> Andreas' wallet hasn't done that for years. Are you repeating this from
> some very old memory or do you actually see this issue in reality?
>
> The only time you're forced to wait for confirmations is when you have an
> unconfirmed inbound transaction, and thus the sender is unknown.
I see this behavior all the time. I am using the latest release, as far as I know. Version 4.30.
The same behavior occurs in the Testnet3 variant of the app. Go in there with an empty wallet and receive one payment and wait for it to confirm. Then send a payment and, before it confirms, try to send another one. The wallet won't let you send the second payment. It'll say something like, "You need x.xxxxxx more bitcoins to make this payment." But if you wait for your first payment to confirm, then you'll be able to make the second payment.
If it matters, I configure the app to connect only to my own trusted Bitcoin node, so I only ever have one active connection at most. I notice that outgoing payments never show as "Sent" until they appear in a block, presumably because the app never sees the transaction come in over any connection.
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-25 20:03 ` Matt Whitlock
@ 2015-05-25 20:29 ` Andreas Schildbach
2015-05-25 21:05 ` Peter Todd
2015-05-25 21:14 ` Warren Togami Jr.
2015-05-25 21:12 ` Mike Hearn
1 sibling, 2 replies; 32+ messages in thread
From: Andreas Schildbach @ 2015-05-25 20:29 UTC (permalink / raw)
To: bitcoin-development
On 05/25/2015 10:03 PM, Matt Whitlock wrote:
> On Monday, 25 May 2015, at 8:41 pm, Mike Hearn wrote:
>>> some wallets (e.g., Andreas Schildbach's wallet) don't even allow it - you
>>> can only spend confirmed UTXOs. I can't tell you how aggravating it is to
>>> have to tell a friend, "Oh, oops, I can't pay you yet. I have to wait for
>>> the last transaction I did to confirm first." All the more aggravating
>>> because I know, if I have multiple UTXOs in my wallet, I can make multiple
>>> spends within the same block.
>>
>> Andreas' wallet hasn't done that for years. Are you repeating this from
>> some very old memory or do you actually see this issue in reality?
>>
>> The only time you're forced to wait for confirmations is when you have an
>> unconfirmed inbound transaction, and thus the sender is unknown.
>
> I see this behavior all the time. I am using the latest release, as far as I know. Version 4.30.
>
> The same behavior occurs in the Testnet3 variant of the app. Go in there with an empty wallet and receive one payment and wait for it to confirm. Then send a payment and, before it confirms, try to send another one. The wallet won't let you send the second payment. It'll say something like, "You need x.xxxxxx more bitcoins to make this payment." But if you wait for your first payment to confirm, then you'll be able to make the second payment.
>
> If it matters, I configure the app to connect only to my own trusted Bitcoin node, so I only ever have one active connection at most. I notice that outgoing payments never show as "Sent" until they appear in a block, presumably because the app never sees the transaction come in over any connection.
Yes, that's the issue. Because you're connecting only to one node, you
don't get any instant confirmations -- due to a Bitcoin protocol
limitation you can only get them from nodes you don't post the tx to.
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-25 20:29 ` Andreas Schildbach
@ 2015-05-25 21:05 ` Peter Todd
2015-05-26 12:40 ` Andreas Schildbach
2015-05-25 21:14 ` Warren Togami Jr.
1 sibling, 1 reply; 32+ messages in thread
From: Peter Todd @ 2015-05-25 21:05 UTC (permalink / raw)
To: Andreas Schildbach; +Cc: bitcoin-development
[-- Attachment #1: Type: text/plain, Size: 1366 bytes --]
On Mon, May 25, 2015 at 10:29:26PM +0200, Andreas Schildbach wrote:
> > I see this behavior all the time. I am using the latest release, as far as I know. Version 4.30.
> >
> > The same behavior occurs in the Testnet3 variant of the app. Go in there with an empty wallet and receive one payment and wait for it to confirm. Then send a payment and, before it confirms, try to send another one. The wallet won't let you send the second payment. It'll say something like, "You need x.xxxxxx more bitcoins to make this payment." But if you wait for your first payment to confirm, then you'll be able to make the second payment.
> >
> > If it matters, I configure the app to connect only to my own trusted Bitcoin node, so I only ever have one active connection at most. I notice that outgoing payments never show as "Sent" until they appear in a block, presumably because the app never sees the transaction come in over any connection.
>
> Yes, that's the issue. Because you're connecting only to one node, you
> don't get any instant confirmations -- due to a Bitcoin protocol
> limitation you can only get them from nodes you don't post the tx to.
Odd, I just tried the above as well - with multiple peers connected -
and had the exact same problem.
--
'peter'[:-1]@petertodd.org
00000000000000000e83c311f4244e4eefb54aa845abb181e46f16d126ab21e1
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-25 21:05 ` Peter Todd
@ 2015-05-26 12:40 ` Andreas Schildbach
0 siblings, 0 replies; 32+ messages in thread
From: Andreas Schildbach @ 2015-05-26 12:40 UTC (permalink / raw)
To: bitcoin-development
On 05/25/2015 11:05 PM, Peter Todd wrote:
> On Mon, May 25, 2015 at 10:29:26PM +0200, Andreas Schildbach wrote:
>>> I see this behavior all the time. I am using the latest release, as far as I know. Version 4.30.
>>>
>>> The same behavior occurs in the Testnet3 variant of the app. Go in there with an empty wallet and receive one payment and wait for it to confirm. Then send a payment and, before it confirms, try to send another one. The wallet won't let you send the second payment. It'll say something like, "You need x.xxxxxx more bitcoins to make this payment." But if you wait for your first payment to confirm, then you'll be able to make the second payment.
>>>
>>> If it matters, I configure the app to connect only to my own trusted Bitcoin node, so I only ever have one active connection at most. I notice that outgoing payments never show as "Sent" until they appear in a block, presumably because the app never sees the transaction come in over any connection.
>>
>> Yes, that's the issue. Because you're connecting only to one node, you
>> don't get any instant confirmations -- due to a Bitcoin protocol
>> limitation you can only get them from nodes you don't post the tx to.
>
> Odd, I just tried the above as well - with multiple peers connected -
> and had the exact same problem.
It should work, I'm testing this regularly. Can you report an issue
through the app and attach your log when this happens again?
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-25 20:29 ` Andreas Schildbach
2015-05-25 21:05 ` Peter Todd
@ 2015-05-25 21:14 ` Warren Togami Jr.
1 sibling, 0 replies; 32+ messages in thread
From: Warren Togami Jr. @ 2015-05-25 21:14 UTC (permalink / raw)
Cc: Bitcoin Dev
On Mon, May 25, 2015 at 1:29 PM, Andreas Schildbach
<andreas@schildbach•de> wrote:
> Yes, that's the issue. Because you're connecting only to one node, you
> don't get any instant confirmations -- due to a Bitcoin protocol
> limitation you can only get them from nodes you don't post the tx to.
Is it really wise to call this a "confirmation"? All this is really
telling you is one seemingly random peer has relayed the transaction
back to you that you sent to a presumably different seemingly random
peer.
Warren
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-25 20:03 ` Matt Whitlock
2015-05-25 20:29 ` Andreas Schildbach
@ 2015-05-25 21:12 ` Mike Hearn
1 sibling, 0 replies; 32+ messages in thread
From: Mike Hearn @ 2015-05-25 21:12 UTC (permalink / raw)
To: Matt Whitlock; +Cc: Bitcoin Dev
[-- Attachment #1: Type: text/plain, Size: 570 bytes --]
>
> If it matters, I configure the app to connect only to my own trusted
> Bitcoin node, so I only ever have one active connection at most.
Ah, I see, non default configuration. Because the Bitcoin network can and
does change in backwards incompatible ways, the app wants to see that the
transaction it made actually propagated across the network. If you set a
trusted node it won't see that.
Probably the logic should be tweaked so if you set a trusted node you're
just assumed to know what you're doing and we assume the transactions we
make ourselves always work.
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-09 17:09 Jim Phillips
` (3 preceding siblings ...)
2015-05-10 2:11 ` Matt Whitlock
@ 2015-05-10 13:35 ` Bob McElrath
2015-05-10 14:33 ` Jeff Garzik
2015-05-12 19:50 ` Danny Thorpe
2015-05-25 18:44 ` Mike Hearn
6 siblings, 1 reply; 32+ messages in thread
From: Bob McElrath @ 2015-05-10 13:35 UTC (permalink / raw)
To: bitcoin-development
[-- Attachment #1.1: Type: text/plain, Size: 5154 bytes --]
This is my biggest headache with practical bitcoin usage. I'd love to hear it if
anyone has any clever solutions to the wallet/utxo locked problem. Spending
unconfirmed outputs really requires a different security model on the part of
the receiver than #confirmations, but isn't inherently bad if the receiver has a
better security model and knows how to compute the probability that an
unconfirmed-spend will get confirmed. Of course the bigger problem is wallet
software that refuses to spend unconfirmed outputs.
I've thought a bit about a fork/merge design: if the change were computed by the
network instead of the submitter, two transactions having the same change
address and a common input could be straightforwardly merged or split (in a
reorg), where with bitcoin currently it would be considered a double-spend. Of
course that has big privacy implications since it directly exposes the change
address, and is a hard fork, but is much closer to what people expect of a
debit-based "account" in traditional banking.
The fact of the matter is that having numerous sequential debits on an account
is an extremely common use case, and bitcoin is obtuse in this respect.
On May 9, 2015 1:09:32 PM EDT, Jim Phillips <jim@ergophobia•org> wrote:
>Forgive me if this idea has been suggested before, but I made this
>suggestion on reddit and I got some feedback recommending I also bring
>it
>to this list -- so here goes.
>
>I wonder if there isn't perhaps a simpler way of dealing with UTXO
>growth.
>What if, rather than deal with the issue at the protocol level, we deal
>with it at the source of the problem -- the wallets. Right now, the
>typical
>wallet selects only the minimum number of unspent outputs when building
>a
>transaction. The goal is to keep the transaction size to a minimum so
>that
>the fee stays low. Consequently, lots of unspent outputs just don't get
>used, and are left lying around until some point in the future.
>
>What if we started designing wallets to consolidate unspent outputs?
>When
>selecting unspent outputs for a transaction, rather than choosing just
>the
>minimum number from a particular address, why not select them ALL? Take
>all
>of the UTXOs from a particular address or wallet, send however much
>needs
>to be spent to the payee, and send the rest back to the same address or
>a
>change address as a single output? Through this method, we should wind
>up
>shrinking the UTXO database over time rather than growing it with each
>transaction. Obviously, as Bitcoin gains wider adoption, the UTXO
>database
>will grow, simply because there are 7 billion people in the world, and
>eventually a good percentage of them will have one or more wallets with
>spendable bitcoin. But this idea could limit the growth at least.
>
>The vast majority of users are running one of a handful of different
>wallet
>apps: Core, Electrum; Armory; Mycelium; Breadwallet; Coinbase; Circle;
>Blockchain.info; and maybe a few others. The developers of all these
>wallets have a vested interest in the continued usefulness of Bitcoin,
>and
>so should not be opposed to changing their UTXO selection algorithms to
>one
>that reduces the UTXO database instead of growing it.
>
>>From the miners perspective, even though these types of transactions
>would
>be larger, the fee could stay low. Miners actually benefit from them in
>that it reduces the amount of storage they need to dedicate to holding
>the
>UTXO. So miners are incentivized to mine these types of transactions
>with a
>higher priority despite a low fee.
>
>Relays could also get in on the action and enforce this type of
>behavior by
>refusing to relay or deprioritizing the relay of transactions that
>don't
>use all of the available UTXOs from the addresses used as inputs.
>Relays
>are not only the ones who benefit the most from a reduction of the UTXO
>database, they're also in the best position to promote good behavior.
>
>--
>*James G. Phillips IV*
><https://plus.google.com/u/0/113107039501292625391/posts>
>
>*"Don't bunt. Aim out of the ball park. Aim for the company of
>immortals."
>-- David Ogilvy*
>
>*This message was created with 100% recycled electrons. Please think
>twice
>before printing.*
>
>
>!DSPAM:554e4e5450787476022393!
>
>
>------------------------------------------------------------------------
>
>------------------------------------------------------------------------------
>One dashboard for servers and applications across
>Physical-Virtual-Cloud
>Widest out-of-the-box monitoring support with 50+ applications
>Performance metrics, stats and reports that give you Actionable
>Insights
>Deep dive visibility with transaction tracing using APM Insight.
>http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
>
>!DSPAM:554e4e5450787476022393!
>
>
>------------------------------------------------------------------------
>
>_______________________________________________
>Bitcoin-development mailing list
>Bitcoin-development@lists•sourceforge.net
>https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>
>
>!DSPAM:554e4e5450787476022393!
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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[-- Attachment #2: Digital signature --]
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^ permalink raw reply [flat|nested] 32+ messages in thread* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-10 13:35 ` Bob McElrath
@ 2015-05-10 14:33 ` Jeff Garzik
2015-05-10 14:42 ` Bob McElrath
0 siblings, 1 reply; 32+ messages in thread
From: Jeff Garzik @ 2015-05-10 14:33 UTC (permalink / raw)
To: Bob McElrath, Jim Phillips; +Cc: Bitcoin Dev
[-- Attachment #1: Type: text/plain, Size: 12181 bytes --]
This has been frequently explored on IRC.
My general conclusion is "dollar bills" - pick highly common denominations
of bitcoins. Aggregate to obtain these denominations, but do not aggregate
further.
This permits merge avoidance (privacy++), easy coinjoin where many hide in
the noise (privacy++), wallet dust de-fragmentation, while avoiding the
over-aggregation problem where you have consolidated down to one output.
Thus a wallet would have several consolidation targets.
Another strategy is simply doubling outputs. Say you pay 0.1 BTC to
Starbucks. Add another 0.1 BTC output to yourself, and a final change
output. Who can say which output goes to Starbucks?
There are many iterations and trade-offs between fragmentation and privacy.
On Sun, May 10, 2015 at 9:35 AM, Bob McElrath <bob_bitcoin@mcelrath•org>
wrote:
> This is my biggest headache with practical bitcoin usage. I'd love to hear
> it if
> anyone has any clever solutions to the wallet/utxo locked problem. Spending
> unconfirmed outputs really requires a different security model on the part
> of
> the receiver than #confirmations, but isn't inherently bad if the receiver
> has a
> better security model and knows how to compute the probability that an
> unconfirmed-spend will get confirmed. Of course the bigger problem is
> wallet
> software that refuses to spend unconfirmed outputs.
>
> I've thought a bit about a fork/merge design: if the change were computed
> by the
> network instead of the submitter, two transactions having the same change
> address and a common input could be straightforwardly merged or split (in a
> reorg), where with bitcoin currently it would be considered a
> double-spend. Of
> course that has big privacy implications since it directly exposes the
> change
> address, and is a hard fork, but is much closer to what people expect of a
> debit-based "account" in traditional banking.
>
> The fact of the matter is that having numerous sequential debits on an
> account
> is an extremely common use case, and bitcoin is obtuse in this respect.
>
> On May 9, 2015 1:09:32 PM EDT, Jim Phillips <jim@ergophobia•org> wrote:
> >Forgive me if this idea has been suggested before, but I made this
> >suggestion on reddit and I got some feedback recommending I also bring
> >it
> >to this list -- so here goes.
> >
> >I wonder if there isn't perhaps a simpler way of dealing with UTXO
> >growth.
> >What if, rather than deal with the issue at the protocol level, we deal
> >with it at the source of the problem -- the wallets. Right now, the
> >typical
> >wallet selects only the minimum number of unspent outputs when building
> >a
> >transaction. The goal is to keep the transaction size to a minimum so
> >that
> >the fee stays low. Consequently, lots of unspent outputs just don't get
> >used, and are left lying around until some point in the future.
> >
> >What if we started designing wallets to consolidate unspent outputs?
> >When
> >selecting unspent outputs for a transaction, rather than choosing just
> >the
> >minimum number from a particular address, why not select them ALL? Take
> >all
> >of the UTXOs from a particular address or wallet, send however much
> >needs
> >to be spent to the payee, and send the rest back to the same address or
> >a
> >change address as a single output? Through this method, we should wind
> >up
> >shrinking the UTXO database over time rather than growing it with each
> >transaction. Obviously, as Bitcoin gains wider adoption, the UTXO
> >database
> >will grow, simply because there are 7 billion people in the world, and
> >eventually a good percentage of them will have one or more wallets with
> >spendable bitcoin. But this idea could limit the growth at least.
> >
> >The vast majority of users are running one of a handful of different
> >wallet
> >apps: Core, Electrum; Armory; Mycelium; Breadwallet; Coinbase; Circle;
> >Blockchain.info; and maybe a few others. The developers of all these
> >wallets have a vested interest in the continued usefulness of Bitcoin,
> >and
> >so should not be opposed to changing their UTXO selection algorithms to
> >one
> >that reduces the UTXO database instead of growing it.
> >
> >>From the miners perspective, even though these types of transactions
> >would
> >be larger, the fee could stay low. Miners actually benefit from them in
> >that it reduces the amount of storage they need to dedicate to holding
> >the
> >UTXO. So miners are incentivized to mine these types of transactions
> >with a
> >higher priority despite a low fee.
> >
> >Relays could also get in on the action and enforce this type of
> >behavior by
> >refusing to relay or deprioritizing the relay of transactions that
> >don't
> >use all of the available UTXOs from the addresses used as inputs.
> >Relays
> >are not only the ones who benefit the most from a reduction of the UTXO
> >database, they're also in the best position to promote good behavior.
> >
> >--
> >*James G. Phillips IV*
> ><https://plus.google.com/u/0/113107039501292625391/posts>
> >
> >*"Don't bunt. Aim out of the ball park. Aim for the company of
> >immortals."
> >-- David Ogilvy*
> >
> >*This message was created with 100% recycled electrons. Please think
> >twice
> >before printing.*
> >
> >
> >!DSPAM:554e4e5450787476022393!
> >
> >
> >------------------------------------------------------------------------
> >
>
> >------------------------------------------------------------------------------
> >One dashboard for servers and applications across
> >Physical-Virtual-Cloud
> >Widest out-of-the-box monitoring support with 50+ applications
> >Performance metrics, stats and reports that give you Actionable
> >Insights
> >Deep dive visibility with transaction tracing using APM Insight.
> >http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
> >
> >!DSPAM:554e4e5450787476022393!
> >
> >
> >------------------------------------------------------------------------
> >
> >_______________________________________________
> >Bitcoin-development mailing list
> >Bitcoin-development@lists•sourceforge.net
> >https://lists.sourceforge.net/lists/listinfo/bitcoin-development
> >
> >
> >!DSPAM:554e4e5450787476022393!
>
> --
> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>
> This is my biggest headache with practical bitcoin usage. I'd love to hear
> it if anyone has any clever solutions to the wallet/utxo locked problem.
> Spending unconfirmed outputs really requires a different security model on
> the part of the receiver than #confirmations, but isn't inherently bad if
> the receiver has a better security model and knows how to compute the
> probability that an unconfirmed-spend will get confirmed. Of course the
> bigger problem is wallet software that refuses to spend unconfirmed outputs.
>
> I've thought a bit about a fork/merge design: if the change were computed
> by the network instead of the submitter, two transactions having the same
> change address could be straightforwardly merged or split (in a reorg). Of
> course that has big privacy implications and is pretty far from bitcoin's
> design, but is much closer to what people expect of a debit-based "account"
> in traditional banking.
>
> The fact of the matter is that having numerous sequential debits on an
> account is an extremely common use case, and bitcoin is obtuse in this
> respect.
>
> On May 9, 2015 1:09:32 PM EDT, Jim Phillips <jim@ergophobia•org> wrote:
>>
>> Forgive me if this idea has been suggested before, but I made this
>> suggestion on reddit and I got some feedback recommending I also bring it
>> to this list -- so here goes.
>>
>> I wonder if there isn't perhaps a simpler way of dealing with UTXO
>> growth. What if, rather than deal with the issue at the protocol level, we
>> deal with it at the source of the problem -- the wallets. Right now, the
>> typical wallet selects only the minimum number of unspent outputs when
>> building a transaction. The goal is to keep the transaction size to a
>> minimum so that the fee stays low. Consequently, lots of unspent outputs
>> just don't get used, and are left lying around until some point in the
>> future.
>>
>> What if we started designing wallets to consolidate unspent outputs? When
>> selecting unspent outputs for a transaction, rather than choosing just the
>> minimum number from a particular address, why not select them ALL? Take all
>> of the UTXOs from a particular address or wallet, send however much needs
>> to be spent to the payee, and send the rest back to the same address or a
>> change address as a single output? Through this method, we should wind up
>> shrinking the UTXO database over time rather than growing it with each
>> transaction. Obviously, as Bitcoin gains wider adoption, the UTXO database
>> will grow, simply because there are 7 billion people in the world, and
>> eventually a good percentage of them will have one or more wallets with
>> spendable bitcoin. But this idea could limit the growth at least.
>>
>> The vast majority of users are running one of a handful of different
>> wallet apps: Core, Electrum; Armory; Mycelium; Breadwallet; Coinbase;
>> Circle; Blockchain.info; and maybe a few others. The developers of all
>> these wallets have a vested interest in the continued usefulness of
>> Bitcoin, and so should not be opposed to changing their UTXO selection
>> algorithms to one that reduces the UTXO database instead of growing it.
>>
>> From the miners perspective, even though these types of transactions
>> would be larger, the fee could stay low. Miners actually benefit from them
>> in that it reduces the amount of storage they need to dedicate to holding
>> the UTXO. So miners are incentivized to mine these types of transactions
>> with a higher priority despite a low fee.
>>
>> Relays could also get in on the action and enforce this type of behavior
>> by refusing to relay or deprioritizing the relay of transactions that don't
>> use all of the available UTXOs from the addresses used as inputs. Relays
>> are not only the ones who benefit the most from a reduction of the UTXO
>> database, they're also in the best position to promote good behavior.
>>
>> --
>> *James G. Phillips IV*
>> <https://plus.google.com/u/0/113107039501292625391/posts>
>>
>> *"Don't bunt. Aim out of the ball park. Aim for the company of
>> immortals." -- David Ogilvy*
>>
>> *This message was created with 100% recycled electrons. Please think
>> twice before printing.*
>> !DSPAM:554e4e5450787476022393!
>>
>> ------------------------------
>>
>> One dashboard for servers and applications across Physical-Virtual-Cloud
>> Widest out-of-the-box monitoring support with 50+ applications
>> Performance metrics, stats and reports that give you Actionable Insights
>> Deep dive visibility with transaction tracing using APM Insight.
>> http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
>>
>> !DSPAM:554e4e5450787476022393!
>>
>> ------------------------------
>>
>> Bitcoin-development mailing list
>> Bitcoin-development@lists•sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>>
>>
>> !DSPAM:554e4e5450787476022393!
>>
>>
> --
> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>
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>
>
> ------------------------------------------------------------------------------
> One dashboard for servers and applications across Physical-Virtual-Cloud
> Widest out-of-the-box monitoring support with 50+ applications
> Performance metrics, stats and reports that give you Actionable Insights
> Deep dive visibility with transaction tracing using APM Insight.
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> _______________________________________________
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--
Jeff Garzik
Bitcoin core developer and open source evangelist
BitPay, Inc. https://bitpay.com/
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-10 14:33 ` Jeff Garzik
@ 2015-05-10 14:42 ` Bob McElrath
0 siblings, 0 replies; 32+ messages in thread
From: Bob McElrath @ 2015-05-10 14:42 UTC (permalink / raw)
To: Bitcoin Dev
That's a lot of work, a lot of extra utxo's, and a lot of blockchain spam, just
so I can do a convoluted form of arithmetic on my balance.
If a tx contained an explicit miner fee and a change address, but did not
compute the change, letting the network compute it (and therefore merge
transactions spending the same utxo), could one add some form of ring signature
a la Dash to alleviate the worsened privacy implications?
Jeff Garzik [jgarzik@bitpay•com] wrote:
> This has been frequently explored on IRC.
>
> My general conclusion is "dollar bills" - pick highly common denominations of
> bitcoins. Aggregate to obtain these denominations, but do not aggregate
> further.
>
> This permits merge avoidance (privacy++), easy coinjoin where many hide in the
> noise (privacy++), wallet dust de-fragmentation, while avoiding the
> over-aggregation problem where you have consolidated down to one output.
>
> Thus a wallet would have several consolidation targets.
>
> Another strategy is simply doubling outputs. Say you pay 0.1 BTC to
> Starbucks. Add another 0.1 BTC output to yourself, and a final change output.
> Who can say which output goes to Starbucks?
>
> There are many iterations and trade-offs between fragmentation and privacy.
--
Cheers, Bob McElrath
"The individual has always had to struggle to keep from being overwhelmed by
the tribe. If you try it, you will be lonely often, and sometimes frightened.
But no price is too high to pay for the privilege of owning yourself."
-- Friedrich Nietzsche
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-09 17:09 Jim Phillips
` (4 preceding siblings ...)
2015-05-10 13:35 ` Bob McElrath
@ 2015-05-12 19:50 ` Danny Thorpe
2015-05-25 18:44 ` Mike Hearn
6 siblings, 0 replies; 32+ messages in thread
From: Danny Thorpe @ 2015-05-12 19:50 UTC (permalink / raw)
To: Jim Phillips; +Cc: Bitcoin Dev
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Having thousands of utxos floating around for a single address is clearly a
bad thing - it creates a lot of memory load on bitcoin nodes.
However, having only one utxo for an address is also a bad thing, for
concurrent operations.
Having "several" utxos available to spend is good for parallelism, so that
2 or more tasks which are spending from the same address don't have to line
up single file waiting for one of the tasks to publish a tx first so that
the next task can spend the (unconfirmed) change output of the first.
Requiring/Forcing/Having a single output carry the entire balance of an
address does not work at scale. (Yes, this presumes that the tasks are
coordinated so that they don't attempt to spend the same outputs. Internal
coordination is solvable.)
In multiple replies, you push for having "all" utxos of an address spent in
one transaction. Why all? If the objective is to reduce the size of the
utxo pool, it would be sufficient simply to recommend that wallets and
other spenders consume more utxos than they create, on average.
I'm ok with "consume more utxos than you generate" as a good citizen / best
practices recommendation, but a requirement that all prior outputs must be
spent in one transaction seems excessive and impractical.
-Danny
On Sat, May 9, 2015 at 10:09 AM, Jim Phillips <jim@ergophobia•org> wrote:
> Forgive me if this idea has been suggested before, but I made this
> suggestion on reddit and I got some feedback recommending I also bring it
> to this list -- so here goes.
>
> I wonder if there isn't perhaps a simpler way of dealing with UTXO growth.
> What if, rather than deal with the issue at the protocol level, we deal
> with it at the source of the problem -- the wallets. Right now, the typical
> wallet selects only the minimum number of unspent outputs when building a
> transaction. The goal is to keep the transaction size to a minimum so that
> the fee stays low. Consequently, lots of unspent outputs just don't get
> used, and are left lying around until some point in the future.
>
> What if we started designing wallets to consolidate unspent outputs? When
> selecting unspent outputs for a transaction, rather than choosing just the
> minimum number from a particular address, why not select them ALL? Take all
> of the UTXOs from a particular address or wallet, send however much needs
> to be spent to the payee, and send the rest back to the same address or a
> change address as a single output? Through this method, we should wind up
> shrinking the UTXO database over time rather than growing it with each
> transaction. Obviously, as Bitcoin gains wider adoption, the UTXO database
> will grow, simply because there are 7 billion people in the world, and
> eventually a good percentage of them will have one or more wallets with
> spendable bitcoin. But this idea could limit the growth at least.
>
> The vast majority of users are running one of a handful of different
> wallet apps: Core, Electrum; Armory; Mycelium; Breadwallet; Coinbase;
> Circle; Blockchain.info; and maybe a few others. The developers of all
> these wallets have a vested interest in the continued usefulness of
> Bitcoin, and so should not be opposed to changing their UTXO selection
> algorithms to one that reduces the UTXO database instead of growing it.
>
> From the miners perspective, even though these types of transactions would
> be larger, the fee could stay low. Miners actually benefit from them in
> that it reduces the amount of storage they need to dedicate to holding the
> UTXO. So miners are incentivized to mine these types of transactions with a
> higher priority despite a low fee.
>
> Relays could also get in on the action and enforce this type of behavior
> by refusing to relay or deprioritizing the relay of transactions that don't
> use all of the available UTXOs from the addresses used as inputs. Relays
> are not only the ones who benefit the most from a reduction of the UTXO
> database, they're also in the best position to promote good behavior.
>
> --
> *James G. Phillips IV*
> <https://plus.google.com/u/0/113107039501292625391/posts>
>
> *"Don't bunt. Aim out of the ball park. Aim for the company of immortals."
> -- David Ogilvy*
>
> *This message was created with 100% recycled electrons. Please think
> twice before printing.*
>
>
> ------------------------------------------------------------------------------
> One dashboard for servers and applications across Physical-Virtual-Cloud
> Widest out-of-the-box monitoring support with 50+ applications
> Performance metrics, stats and reports that give you Actionable Insights
> Deep dive visibility with transaction tracing using APM Insight.
> http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
> _______________________________________________
> Bitcoin-development mailing list
> Bitcoin-development@lists•sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>
>
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^ permalink raw reply [flat|nested] 32+ messages in thread* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-09 17:09 Jim Phillips
` (5 preceding siblings ...)
2015-05-12 19:50 ` Danny Thorpe
@ 2015-05-25 18:44 ` Mike Hearn
2015-05-25 21:26 ` Peter Todd
6 siblings, 1 reply; 32+ messages in thread
From: Mike Hearn @ 2015-05-25 18:44 UTC (permalink / raw)
To: Jim Phillips; +Cc: Bitcoin Dev
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Wallets are incentivised to do a better job with defragmentation already,
as if you have lots of tiny UTXOs then your fees end up being huge when
trying to make a payment.
The reason they largely don't is just one of manpower. Nobody is working on
it.
As a wallet developer myself, one way I'd like to see this issue be fixed
by making free transactions more reliable. Then wallets can submit free
transactions to the network to consolidate UTXOs together, e.g. at night
when the user is sleeping. They would then fit into whatever space is
available in the block during periods of low demand, like on Sunday.
If we don't do this then wallets won't automatically defragment, as we'd be
unable to explain to the user why their money is slowly leaking out of
their wallet without them doing anything. Trying to explain the existing
transaction fees is hard enough already ("I thought bitcoin doesn't have
banks" etc).
There is another way: as the fee is based on a rounded 1kb calculation, if
you go into the next fee band adding some more outputs and making a bigger
change output becomes "free" for another output or two. But wallets don't
exploit this today.
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^ permalink raw reply [flat|nested] 32+ messages in thread* Re: [Bitcoin-development] A suggestion for reducing the size of the UTXO database
2015-05-25 18:44 ` Mike Hearn
@ 2015-05-25 21:26 ` Peter Todd
2015-05-25 22:03 ` Mike Hearn
0 siblings, 1 reply; 32+ messages in thread
From: Peter Todd @ 2015-05-25 21:26 UTC (permalink / raw)
To: Mike Hearn; +Cc: Bitcoin Dev
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On Mon, May 25, 2015 at 08:44:18PM +0200, Mike Hearn wrote:
> Wallets are incentivised to do a better job with defragmentation already,
> as if you have lots of tiny UTXOs then your fees end up being huge when
> trying to make a payment.
>
> The reason they largely don't is just one of manpower. Nobody is working on
> it.
>
> As a wallet developer myself, one way I'd like to see this issue be fixed
> by making free transactions more reliable. Then wallets can submit free
> transactions to the network to consolidate UTXOs together, e.g. at night
> when the user is sleeping. They would then fit into whatever space is
> available in the block during periods of low demand, like on Sunday.
This can cause problems as until those transactions confirm, even more
of the user's outputs are unavailable for spending, causing confusion as
to why they can't send their full balance. It's also inefficient, as in
the case where the user does try to send a small payment that could be
satisfied by one or more of these small UTXO's, the wallet has to use a
larger UTXO.
With replace-by-fee however this problem goes away, as you can simply
double-spend the pending defragmentation transactions instead if they
are still unconfirmed when you need to use them.
--
'peter'[:-1]@petertodd.org
00000000000000000aa9033c06c10d6131eafa3754c3157d74c2267c1dd2ca35
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^ permalink raw reply [flat|nested] 32+ messages in thread