From: Mark Walters Date: Mon, 2 Jun 2014 13:51:01 +0000 (+0100) Subject: Re: Deduplication ? X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=cf8b1c6d009e7f274e84411867ccd5990f0c2bf6;p=notmuch-archives.git Re: Deduplication ? --- diff --git a/6f/6a01c2b5c69ff607c31f47913d0c8ee0bfd2db b/6f/6a01c2b5c69ff607c31f47913d0c8ee0bfd2db new file mode 100644 index 000000000..af7e5912c --- /dev/null +++ b/6f/6a01c2b5c69ff607c31f47913d0c8ee0bfd2db @@ -0,0 +1,130 @@ +Return-Path: +X-Original-To: notmuch@notmuchmail.org +Delivered-To: notmuch@notmuchmail.org +Received: from localhost (localhost [127.0.0.1]) + by olra.theworths.org (Postfix) with ESMTP id 1804F431FBC + for ; Mon, 2 Jun 2014 06:51:13 -0700 (PDT) +X-Virus-Scanned: Debian amavisd-new at olra.theworths.org +X-Spam-Flag: NO +X-Spam-Score: 0.502 +X-Spam-Level: +X-Spam-Status: No, score=0.502 tagged_above=-999 required=5 + tests=[DKIM_ADSP_CUSTOM_MED=0.001, FREEMAIL_FROM=0.001, + NML_ADSP_CUSTOM_MED=1.2, RCVD_IN_DNSWL_LOW=-0.7] autolearn=disabled +Received: from olra.theworths.org ([127.0.0.1]) + by localhost (olra.theworths.org [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id z42UBbi1kTKh for ; + Mon, 2 Jun 2014 06:51:05 -0700 (PDT) +Received: from mail2.qmul.ac.uk (mail2.qmul.ac.uk [138.37.6.6]) + (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) + (No client certificate requested) + by olra.theworths.org (Postfix) with ESMTPS id A5A72431FAE + for ; Mon, 2 Jun 2014 06:51:05 -0700 (PDT) +Received: from smtp.qmul.ac.uk ([138.37.6.40]) + by mail2.qmul.ac.uk with esmtp (Exim 4.71) + (envelope-from ) + id 1WrSdj-0003eJ-4U; Mon, 02 Jun 2014 14:51:03 +0100 +Received: from 5751dfa2.skybroadband.com ([87.81.223.162] helo=localhost) + by smtp.qmul.ac.uk with esmtpsa (TLSv1:AES128-SHA:128) (Exim 4.71) + (envelope-from ) + id 1WrSdi-0005uz-Rf; Mon, 02 Jun 2014 14:51:03 +0100 +From: Mark Walters +To: Vladimir Marek , notmuch@notmuchmail.org +Subject: Re: Deduplication ? +In-Reply-To: <20140602123212.GA12639@virt.cz.oracle.com> +References: <20140602123212.GA12639@virt.cz.oracle.com> +User-Agent: Notmuch/0.15.2+615~g78e3a93 (http://notmuchmail.org) Emacs/23.4.1 + (i486-pc-linux-gnu) +Date: Mon, 02 Jun 2014 14:51:01 +0100 +Message-ID: <87d2ers9mi.fsf@qmul.ac.uk> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Sender-Host-Address: 87.81.223.162 +X-QM-Geographic: According to ripencc, + this message was delivered by a machine in Britain (UK) (GB). +X-QM-SPAM-Info: Sender has good ham record. :) +X-QM-Body-MD5: dd1566ba4e20a2890032dba656f3d5dc (of first 20000 bytes) +X-SpamAssassin-Score: -0.1 +X-SpamAssassin-SpamBar: / +X-SpamAssassin-Report: The QM spam filters have analysed this message to + determine if it is + spam. We require at least 5.0 points to mark a message as spam. + This message scored -0.1 points. + Summary of the scoring: + * 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail + provider * (markwalters1009[at]gmail.com) + * -0.1 AWL AWL: From: address is in the auto white-list +X-QM-Scan-Virus: ClamAV says the message is clean +X-BeenThere: notmuch@notmuchmail.org +X-Mailman-Version: 2.1.13 +Precedence: list +List-Id: "Use and development of the notmuch mail system." + +List-Unsubscribe: , + +List-Archive: +List-Post: +List-Help: +List-Subscribe: , + +X-List-Received-Date: Mon, 02 Jun 2014 13:51:13 -0000 + + +Vladimir Marek writes: + +> Hi, +> +> I want to import bigger chunk of archived messages into my notmuch +> database. It's about 100k messages. The problem is, that I most probably +> have quite a lot of those messages in the DB. Basically I would like to +> add only those I don't have already. +> +> There are two possibilities +> +> a) I will add all the 100k messages and then remove the duplicities. +> +> b) I will write a script which will parse the message ID's of the +> to-be-added messages and try to match them to the notmuch DB. Adding +> only files I can't find already. +> +> Ad b) might be better option, but I started to play with the idea of +> deduplication. I'm thinking about listing all the message IDs stored in +> DB, listing all files belonging to the IDs and deleting all but one. +> Also I'm thinking about implementing some simple algorithm telling me +> whether the messages are really very similar. Just to be sure I don't +> delete something I don't want to. +> +> Was anyone playing with the idea? + +I am not sure what your use case is but notmuch automatically +deduplicates: that is if the message-id is one it has already seen no +further indexing takes place. The only thing that happens is the new +filename gets added to the list of filenames for the message. + +Thus importing should be almost as fast as if the message were not +there, and the database should be almost identical to what you would get +if you only imported the genuine new messages. + +If you want to save disk space then you could delete the duplicates +after with something like + +notmuch search --output=files --format=text0 --duplicate=2 '*' piped to +xargs -0 + +(but please test it carefully first!) + +I would think something like this is better than trying to parse the +message-ids yourself. + +Best wishes + +Mark + + +> +> -- +> Vlad +> _______________________________________________ +> notmuch mailing list +> notmuch@notmuchmail.org +> http://notmuchmail.org/mailman/listinfo/notmuch