From: "Jorge Timón" <jtimon@jtimon•cc>
To: Peter Todd <pete@petertodd•org>
Cc: Bitcoin Dev <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Making UTXO Set Growth Irrelevant With Low-Latency Delayed TXO Commitments
Date: Thu, 19 May 2016 11:31:26 +0200 [thread overview]
Message-ID: <CABm2gDqcURsug5C21A7dmAMCgU7easbCs=u5sFZy_G4MfyY8mw@mail.gmail.com> (raw)
In-Reply-To: <CABm2gDp9N3ZEZcmF28ESv3V7v_HqU5e5KHY69cSxcVm0t7BeDQ@mail.gmail.com>
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On May 19, 2016 01:53, "Peter Todd" <pete@petertodd•org> wrote:
tip of the tree.
> >
> > How expensive it is to update a leaf from this tree from unspent to
spent?
>
> log2(n) operations.
Updating a leaf is just as expensive as adding a new one?
That's not what I expected.
Or is adding a new one O (1) ?
Anyway, thanks, I'll read this in more detail.
> > Wouldn't it be better to have both an append-only TXO and an append-only
> > STXO (with all spent outputs, not only the latest ones like in your
"STXO")?
>
> Nope. The reason why this doesn't work is apparent when you ask how will
the
> STXO be indexed?
Just the same way the TXO is (you just stop updating the txo leafs from
unspent to spent.
> If it's indexed by outpoint - that is H(txid:n) - to update the STXO you
need
> he entire thing, as the position of any new STXO that you need to add to
the
> STXO tree is random.
>
> OTOH, if you index the STXO by txout creation order, with the first txout
ever
> created having position #0, the second #1, etc. the data you may need to
update
> the STXO later has predictable locality... but now you have something
that's
> basically identical to my proposed insertion-ordered TXO commitment
anyway.
Yeah, that's what I want. Like your append only TXO but for STXO (that way
we avoid ever updating leafs in the TXO, and I suspect there are other
advantages for fraud proofs).
> Incidentally, it's interesting how if a merbinner tree is insertion-order
> indexed you end up with a datastructure that's almost identical to a MMR.
No complain with MMR. My point is having 2 of them separated: one for the
TXO (entries unmutable) and one for the STXO (again, entries unmutable).
Maybe it doesn't make sense, but I would like to understand why.
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next prev parent reply other threads:[~2016-05-19 9:31 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-17 13:23 Peter Todd
2016-05-17 14:03 ` Jameson Lopp
2016-05-17 14:25 ` Eric Lombrozo
2016-05-17 18:01 ` Chris Priest
[not found] ` <CABm2gDoj=6CimHm2C0H_qa=o5SRqWr0ZTGamf-qT-kUjt5WXTA@mail.gmail.com>
[not found] ` <CABm2gDqMQanaY0Eo4QAnx2MrKCSP+v31R6J80jSVx+jOwsVsVw@mail.gmail.com>
2016-05-18 11:14 ` Jorge Timón
2016-05-18 23:53 ` Peter Todd
[not found] ` <CABm2gDrXjg_nSKr-ju0jdXxmMc4N=LQFRwaVU3ix1p-T8CVKdQ@mail.gmail.com>
[not found] ` <CABm2gDrmRf9wjddiMb-TTDE0xkBJ6yMz-bW_aTpDuBvNqrnHzQ@mail.gmail.com>
[not found] ` <CABm2gDqfZh0zOqJN5itVk8eP0nshBsydzT6uryrBdRTcYqyhyA@mail.gmail.com>
[not found] ` <CABm2gDr4ZKvGt3qRPpV+iPgGbpQ5cO66M_bPn2HJPn-eYcQMOg@mail.gmail.com>
[not found] ` <CABm2gDrijEMZW1dMjGTfG-32VGvLZvX-ujP1n5mxBeVLQSsL1Q@mail.gmail.com>
[not found] ` <CABm2gDp9N3ZEZcmF28ESv3V7v_HqU5e5KHY69cSxcVm0t7BeDQ@mail.gmail.com>
2016-05-19 9:31 ` Jorge Timón [this message]
2016-05-19 22:23 ` Nick ODell
2016-05-20 8:45 ` Peter Todd
2016-05-20 9:46 ` Johnson Lau
2016-05-22 8:55 ` Peter Todd
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