From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 11C46A5E for ; Mon, 3 Apr 2017 03:13:54 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-io0-f176.google.com (mail-io0-f176.google.com [209.85.223.176]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 7EB13FC for ; Mon, 3 Apr 2017 03:13:53 +0000 (UTC) Received: by mail-io0-f176.google.com with SMTP id z13so67633903iof.2 for ; Sun, 02 Apr 2017 20:13:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bittorrent-com.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=BbB0u5+o5Jd0h/fnHzpLUzlDLXGVpNpxvWbrfRxAB9w=; b=ZfcNHRLmuOYOx4iA8vXz+2IEDzrkLsZdz9xYeUDimI3WGftW7rgDuFNZn6v340VIZX a7C5RWHdo/tQSmBOHI00C71466HCgFLuq197pf33iA56IR3cM9soRksjQPI6Dt5EB3S1 k8RL3Bbb3Ai+Jr3qQE8+8Pau9c+JeNaZNuuIPmR4eYqw/QsGZwhc45MloyWRX5wKAXoR tWxsu+IoRKgpL8p7J3ha2gYELeOzmw/jJo7Uq3LPzpLQzJySwAZjZyEZ/OuEiutz1qMi gK5SRHj6ZprZ4h1W5LNmTJYdq8+cIuYUC9GLvgUGOjBowEamvSTgZNTOMNoC53+7IA34 bltw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=BbB0u5+o5Jd0h/fnHzpLUzlDLXGVpNpxvWbrfRxAB9w=; b=gv0mL2RliT6Re8EonBLPl6SYF6bmPeta8pCJ1dH2fygHC/vB6lf+zac5FIgCKn5yb5 N9rV+yYk9qJdajs/85TXzE2b6998B5cXt9eUQCmLuvpLHFcsH6LeP+exiwGFvXsnlCaZ ax19NLwml8dDMtMZOkDQg3/hQTEjCFqHo/2OfYZXn+3+2TgHq026z5hXTYW9a934ASTz vxwfcyHiQrb8qt9cqWbM2WHPEJ2Oq58Oy7i6N6RrowrFs55hZaCayeS2nAg8dnTkKui0 MAMVLC5uRiKHLve/OJFUAQSTo7aI0kC9CFsUaSJFKGzs6oBSIwHUit7tGfM5+R2m2Hif K32A== X-Gm-Message-State: AFeK/H2FWRrU9NHQL5eiPmDQUIZSCGu2vXz8ija01OU4qM530ATP2oL4WH4XWZ5pJwmVZxf/sEJFaop17MM66hjx X-Received: by 10.107.11.215 with SMTP id 84mr13876817iol.41.1491189232842; Sun, 02 Apr 2017 20:13:52 -0700 (PDT) MIME-Version: 1.0 Received: by 10.36.184.70 with HTTP; Sun, 2 Apr 2017 20:13:52 -0700 (PDT) In-Reply-To: References: <8f4fSx74VGLlhmwWm7Gwzl5qNMd6okkHcBlCT55CRkYxa_lrEHL-C0hARMXcTaf4CNVIh8no1CHJF-_bmZJRJDsx1H10PCrI45X0D7QdukE=@protonmail.com> From: Bram Cohen Date: Sun, 2 Apr 2017 20:13:52 -0700 Message-ID: To: praxeology_guy , Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary=001a113f8a74845f85054c3a8c3d X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, HTML_MESSAGE, RCVD_IN_DNSWL_NONE, RCVD_IN_SORBS_SPAM autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Subject: Re: [bitcoin-dev] Guessing the spentness status of the pruned relatives X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 03 Apr 2017 03:13:54 -0000 --001a113f8a74845f85054c3a8c3d Content-Type: text/plain; charset=UTF-8 On Sun, Apr 2, 2017 at 1:43 PM, praxeology_guy via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > TL;DR: using spentness bits scales linearly... vs swapping digest leafs > with empties can scale with logorithmically increasing storage > requirements. So if you are using a 32 byte hash and spentness bits, you > are pretty much limited to only being able to prune 8 to 12 layers. This > corresponds to an MMR proof length of 512 to 768 bytes. > Yes the point of the txo bitfield is that the constant factors are so good that it's entirely under control. Making the memory commitments smaller requires that the proofs be kept up to date and increases CPU requirements and proof size. It would be entirely reasonable to make an MMRs of the bitfield or the insertion index data structure but they aren't needed immediately if ever. For the insertion ordering structure it's reasonable to require full nodes to cache the top bunch of layers to make the proofs smaller, but a very expedient approximation of that is to make them simply remember a root per block for all the insertions contained therein, and have full nodes remember all of those. --001a113f8a74845f85054c3a8c3d Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On S= un, Apr 2, 2017 at 1:43 PM, praxeology_guy via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
TL;DR: using spentness bits scales linearly..= . vs swapping digest leafs with empties can scale with logorithmically incr= easing storage requirements.=C2=A0 So if you are using a 32 byte hash and s= pentness bits, you are pretty much limited to only being able to prune 8 to= 12 layers.=C2=A0 This corresponds to an MMR proof length of 512 to 768 byt= es.

Yes the point of the txo bitf= ield is that the constant factors are so good that it's entirely under = control. Making the memory commitments smaller requires that the proofs be = kept up to date and increases CPU requirements and proof size. It would be = entirely reasonable to make an MMRs of the bitfield or the insertion index = data structure but they aren't needed immediately if ever. For the inse= rtion ordering structure it's reasonable to require full nodes to cache= the top bunch of layers to make the proofs smaller, but a very expedient a= pproximation of that is to make them simply remember a root per block for a= ll the insertions contained therein, and have full nodes remember all of th= ose.
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