Path: csiph.com!usenet.pasdenom.info!gegeweb.org!usenet-fr.net!nerim.net!novso.com!newsfeed.xs4all.nl!newsfeed5.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.102 X-Spam-Level: * X-Spam-Evidence: '*H*': 0.80; '*S*': 0.00; 'pursuing': 0.07; 'file,': 0.15; 'binary.': 0.16; 'dave.': 0.16; 'inverse': 0.16; 'mmap': 0.16; 'query,': 0.16; 'simplest': 0.16; 'time"': 0.16; 'wrote:': 0.17; '>>>': 0.18; 'windows': 0.19; 'issue.': 0.20; 'to:name :python-list@python.org': 0.20; "i'd": 0.22; 'paul': 0.24; 'tried': 0.25; 'header:In-Reply-To:1': 0.25; 'header:User- Agent:1': 0.26; '---': 0.26; 'charset:iso-8859-15': 0.26; 'am,': 0.27; 'post': 0.28; 'record': 0.28; '>>>>': 0.29; 'writes:': 0.29; 'file': 0.32; 'to:addr:python-list': 0.33; 'thanks': 0.34; 'really': 0.36; 'but': 0.36; 'subject: (': 0.36; 'possible': 0.37; 'data': 0.37; 'subject:: ': 0.38; 'performance': 0.39; 'to:addr:python.org': 0.39; 'received:192': 0.39; 'little': 0.39; 'received:192.168': 0.40; 'subject:-': 0.40; 'think': 0.40; 'map': 0.61; 'first': 0.61; "you'll": 0.62; 'more': 0.63; 'tricks': 0.65; 'forward': 0.66; 'wish': 0.70; 'now...': 0.84; 'subject:Fast': 0.84; 'subject:read': 0.84; 'subject:write': 0.84; 'findings': 0.91; 'try.': 0.91; 'angel': 0.93 X-SENDER-IP: [213.112.50.224] X-LISTENER: [smtp.bredband.net] X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Ar8jAEs+jVDVcDLgPGdsb2JhbAANN4pSuCUBAQEBOIJSAQEBAQM4QBELGAkWDwkDAgECATEGAQ0GDQYCAQGwMJJqi3WGXQOSQpZkgVok X-IronPort-AV: E=Sophos;i="4.80,667,1344204000"; d="scan'208";a="141139691" Date: Sun, 28 Oct 2012 15:20:45 +0100 From: Virgil Stokes User-Agent: Mozilla/5.0 (Windows NT 6.0; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: "python-list@python.org" Subject: Re: Fast forward-backward (write-read) References: <5086AA35.4000509@it.uu.se> <5086C156.40707@tim.thechases.com> <5086D13F.80006@it.uu.se> <5086DA4D.4060204@tim.thechases.com> <7xr4ooah0t.fsf@ruckus.brouhaha.com> <50879555.7000200@it.uu.se> <508D1469.5060109@davea.name> In-Reply-To: <508D1469.5060109@davea.name> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 20 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1351434054 news.xs4all.nl 6961 [2001:888:2000:d::a6]:48387 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:32313 On 28-Oct-2012 12:18, Dave Angel wrote: > On 10/24/2012 03:14 AM, Virgil Stokes wrote: >> On 24-Oct-2012 01:46, Paul Rubin wrote: >>> Virgil Stokes writes: >>>> Yes, I do wish to inverse the order, but the "forward in time" file >>>> will be in binary. >>> I really think it will be simplest to just write the file in forward >>> order, then use mmap to read it one record at a time. It might be >>> possible to squeeze out a little more performance with reordering tricks >>> but that's the first thing to try. >> Thanks Paul, >> I am working on this approach now... > If you're using mmap to map the whole file, you'll need 64bit Windows to > start with. I'd be interested to know if Windows will allow you to mmap > 100gb at one stroke. Have you tried it, or are you starting by figuring > how to access the data from the mmap? Thanks very much for pursuing my query, Dave. I have not tried it yet --- temporarily side-tracked; but, I will post my findings on this issue.