[Bitcoin-development] Chain pruning

2014-04-10 Thread Mike Hearn
Chain pruning is probably a separate thread, changing subject. Reason is that the actual blocks available are likely to change frequently (if you keep the last week of blocks I doubt anyone would specify blocks to keep in terms of time. More likely it'd be in terms of megabytes, as that's

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Wladimir
On Thu, Apr 10, 2014 at 1:37 PM, Mike Hearn m...@plan99.net wrote: Chain pruning is probably a separate thread, changing subject. Reason is that the actual blocks available are likely to change frequently (if you keep the last week of blocks I doubt anyone would specify blocks to keep in

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Gregory Maxwell
On Thu, Apr 10, 2014 at 4:57 AM, Wladimir laa...@gmail.com wrote: Just wondering: Would there be a use for a [static] node that, say, always serves only the first 10 blocks? Or, even, a static range like block 10 - 20? The last time we discussed this sipa collected data based on

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Wladimir
On Thu, Apr 10, 2014 at 2:10 PM, Gregory Maxwell gmaxw...@gmail.com wrote: But sure I could see a fixed range as also being a useful contribution though I'm struggling to figure out what set of constraints would leave a node without following the consensus? Obviously it has bandwidth if

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Brian Hoffman
This is probably just noise, but what if nodes could compress and store earlier transaction sets (archive sets) and serve them up conditionally. So if there were let's say 100 archive sets of (10,000 blocks) you might have 5 open at any time when you're an active archive node while the others sit

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Mike Hearn
Suggestions always welcome! The main problem with this is that the block chain is mostly random bytes (hashes, keys) so it doesn't compress that well. It compresses a bit, but not enough to change the fundamental physics. However, that does not mean the entire chain has to be stored on expensive

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Brian Hoffman
Looks like only about ~30% disk space savings so I see your point. Is there a critical reason why blocks couldn't be formed into superblocks that are chained together and nodes could serve a specific superblock, which could be pieced together from different nodes to get the full blockchain? This

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Ricardo Filipe
anyway, any kind of compression that comes to the blockchain is orthogonal to pruning. I agree that you will probably want some kind of replication on more recent nodes than on older ones. However, nodes with older blocks don't need to be static, get the block distribution algorithm to sort it

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Ricardo Filipe
that's what blockchain pruning is all about :) 2014-04-10 17:47 GMT+01:00 Brian Hoffman brianchoff...@gmail.com: Looks like only about ~30% disk space savings so I see your point. Is there a critical reason why blocks couldn't be formed into superblocks that are chained together and nodes

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Brian Hoffman
Okay...will let myself out now ;P On Thu, Apr 10, 2014 at 12:54 PM, Ricardo Filipe ricardojdfil...@gmail.comwrote: that's what blockchain pruning is all about :) 2014-04-10 17:47 GMT+01:00 Brian Hoffman brianchoff...@gmail.com: Looks like only about ~30% disk space savings so I see your

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Pieter Wuille
On Thu, Apr 10, 2014 at 6:47 PM, Brian Hoffman brianchoff...@gmail.com wrote: Looks like only about ~30% disk space savings so I see your point. Is there a critical reason why blocks couldn't be formed into superblocks that are chained together and nodes could serve a specific superblock, which

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Brian Hoffman
Ok I think I've got a good understanding of where we're at now. I can promise that the next person to waste your time in 30 days will not be me. I'm pleasantly surprised to see a community that doesn't kickban newcomers and takes the time to explain (re-explain) concepts. Hoping to add

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Paul Rabahy
You say UTXO commitments is a strict reduction in security. If UTXO commitments were rolled in as a soft fork, I do not see any new attacks that could happen to a person trusting the committed UTXO + any remaining blocks to catch up to the head. I would imagine the soft fork to proceed similar to

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Pieter Wuille
On Thu, Apr 10, 2014 at 8:19 PM, Paul Rabahy prab...@gmail.com wrote: Please let me know if I have missed something. A 51% attack can make you believe you were paid, while you weren't. Full node security right now validates everything - there is no way you can ever be made to believe something

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Mark Friedenbach
You took the quote out of context: a full node can copy the chain state from someone else, and check that its hash matches what the block chain commits to. It's important to note that this is a strict reduction in security: we're now trusting that the longest chain (with most proof of work)

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Tier Nolan
On Thu, Apr 10, 2014 at 7:32 PM, Pieter Wuille pieter.wui...@gmail.comwrote: If you trust hashrate for determining which UTXO set is valid, a 51% attack becomes worse in that you can be made to believe a version of history which is in fact invalid. If there are invalidation proofs, then this

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Pieter Wuille
On Thu, Apr 10, 2014 at 10:12 PM, Tier Nolan tier.no...@gmail.com wrote: On Thu, Apr 10, 2014 at 7:32 PM, Pieter Wuille pieter.wui...@gmail.com wrote: If you trust hashrate for determining which UTXO set is valid, a 51% attack becomes worse in that you can be made to believe a version of

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Jesus Cea
On 10/04/14 18:59, Pieter Wuille wrote: It's important to note that this is a strict reduction in security: we're now trusting that the longest chain (with most proof of work) commits to a valid UTXO set (at some point in the past). AFAIK, current bitcoin code code already set blockchain

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Mark Friedenbach
Checkpoints will go away, eventually. On 04/10/2014 02:34 PM, Jesus Cea wrote: On 10/04/14 18:59, Pieter Wuille wrote: It's important to note that this is a strict reduction in security: we're now trusting that the longest chain (with most proof of work) commits to a valid UTXO set (at some

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Jesus Cea
On 11/04/14 00:15, Mark Friedenbach wrote: Checkpoints will go away, eventually. Why?. The points in the forum thread seem pretty sensible. -- Jesús Cea Avión _/_/ _/_/_/_/_/_/ j...@jcea.es - http://www.jcea.es/ _/_/_/_/ _/_/_/_/ _/_/ Twitter:

Re: [Bitcoin-development] Chain pruning

2014-04-10 Thread Gregory Maxwell
On Thu, Apr 10, 2014 at 3:24 PM, Jesus Cea j...@jcea.es wrote: On 11/04/14 00:15, Mark Friedenbach wrote: Checkpoints will go away, eventually. Why?. The points in the forum thread seem pretty sensible. Because with headers first synchronization the major problems that they solve— e.g. block