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From: Gavin Andresen <gavinandresen@gmail.com>
To: "Jorge Timón" <jtimon@jtimon.cc>
Cc: Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Consensus fork activation thresholds: Block.nTime vs median time vs block.nHeight
Date: Thu, 30 Jul 2015 14:16:22 -0400	[thread overview]
Message-ID: <CABsx9T0c10SDHCBy5=iPKVvsNPmKr2ejUxLp0rJPZmPRPQpfig@mail.gmail.com> (raw)
In-Reply-To: <CABm2gDoxr4yY6XPZOEG0CF_iPO+b1H3_yFoKnYa68Y4b=Tcwrw@mail.gmail.com>

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I still think using the version and timestamp fields in the block header
are simplest and best.

Advantages:
  Available to SPV nodes with no change to the network protocol
  Available after headers downloaded, before full block data is available
  Once well past a fork, allows all block validation except validation
against the UTXO to happen in parallel, out-of-order, independent of any
other block.

Disadvantages:
  Not monotonically increasing


I think discussion about transactions in the memory pool are just a
distraction: no matter what criteria is used (timestamp, height, median
time), a blockchain re-organization could mean the validity of transactions
you've accepted into the memory pool (if you're accepting transactions that
switch from valid to invalid at the consensus change -- Core tries hard not
to do that via IsStandard policy) must be re-evaluated.

I don't strongly care if median time or block timestamp is used, I think
either will work. I don't like height, there are too many cases where the
time is known but the block height isn't (see, for example, the
max-outputs-in-a-transaction sanity check computation at line 190 of
bitcoin-tx.cpp -- bitcoin-tx.cpp has no idea what the current block height
is).


-- 
--
Gavin Andresen

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  reply	other threads:[~2015-07-30 18:16 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-29 20:27 [bitcoin-dev] Consensus fork activation thresholds: Block.nTime vs median time vs block.nHeight Jorge Timón
2015-07-30 18:16 ` Gavin Andresen [this message]
2015-08-04 20:02   ` Jorge Timón
2015-08-04 21:29     ` Peter Todd
2015-08-05 19:29       ` Jorge Timón

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