From: Tomi Ollila Date: Mon, 2 Jun 2014 14:17:33 +0000 (+0300) Subject: Re: Deduplication ? X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=0598cba3b9cc98a5dd25a95b1988846a6622548b;p=notmuch-archives.git Re: Deduplication ? --- diff --git a/bd/4f05e435130a53c4ff6bb4bf59008f52f6fc0f b/bd/4f05e435130a53c4ff6bb4bf59008f52f6fc0f new file mode 100644 index 000000000..d1c2471a3 --- /dev/null +++ b/bd/4f05e435130a53c4ff6bb4bf59008f52f6fc0f @@ -0,0 +1,122 @@ +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 55757431FAF + for ; Mon, 2 Jun 2014 07:17:47 -0700 (PDT) +X-Virus-Scanned: Debian amavisd-new at olra.theworths.org +X-Spam-Flag: NO +X-Spam-Score: 0 +X-Spam-Level: +X-Spam-Status: No, score=0 tagged_above=-999 required=5 tests=[none] + 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 a6qh5T1ss-aH for ; + Mon, 2 Jun 2014 07:17:38 -0700 (PDT) +Received: from guru.guru-group.fi (guru.guru-group.fi [46.183.73.34]) + by olra.theworths.org (Postfix) with ESMTP id 6B477431FAE + for ; Mon, 2 Jun 2014 07:17:38 -0700 (PDT) +Received: from guru.guru-group.fi (localhost [IPv6:::1]) + by guru.guru-group.fi (Postfix) with ESMTP id D19C710005E; + Mon, 2 Jun 2014 17:17:33 +0300 (EEST) +From: Tomi Ollila +To: Mark Walters , + Vladimir Marek , notmuch@notmuchmail.org +Subject: Re: Deduplication ? +In-Reply-To: <87d2ers9mi.fsf@qmul.ac.uk> +References: <20140602123212.GA12639@virt.cz.oracle.com> + <87d2ers9mi.fsf@qmul.ac.uk> +User-Agent: Notmuch/0.18+28~gcecaba1 (http://notmuchmail.org) Emacs/24.3.1 + (x86_64-unknown-linux-gnu) +X-Face: HhBM'cA~ +MIME-Version: 1.0 +Content-Type: text/plain +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 14:17:47 -0000 + +On Mon, Jun 02 2014, Mark Walters wrote: + +> 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 + +What if there are 3 duplicates (or 4... ;) + +> +> (but please test it carefully first!) + +One should also have some message content heuristics to determine that the +content is indeed duplicate and not something totally different (not that +we can see the different content anyway... but...) + +> +> I would think something like this is better than trying to parse the +> message-ids yourself. + + +> +> Best wishes +> +> Mark +> + +Tomi + + +> +>> +>> -- +>> Vlad