From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Turner Subject: Re: [PATCH v7 31/33] refs: add LMDB refs storage backend Date: Mon, 29 Feb 2016 20:35:38 -0500 Organization: Twitter Message-ID: <1456796138.18017.77.camel@twopensource.com> References: <1456793586-22082-1-git-send-email-dturner@twopensource.com> <1456793586-22082-32-git-send-email-dturner@twopensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Git Mailing List , Jeff King , Michael Haggerty , Junio C Hamano To: Duy Nguyen X-From: git-owner@vger.kernel.org Tue Mar 01 02:36:00 2016 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1aaZEF-0003KK-NN for gcvg-git-2@plane.gmane.org; Tue, 01 Mar 2016 02:36:00 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750922AbcCABfm (ORCPT ); Mon, 29 Feb 2016 20:35:42 -0500 Received: from mail-qg0-f42.google.com ([209.85.192.42]:33794 "EHLO mail-qg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750725AbcCABfk (ORCPT ); Mon, 29 Feb 2016 20:35:40 -0500 Received: by mail-qg0-f42.google.com with SMTP id b67so131286587qgb.1 for ; Mon, 29 Feb 2016 17:35:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=twopensource-com.20150623.gappssmtp.com; s=20150623; h=message-id:subject:from:to:cc:date:in-reply-to:references :organization:mime-version:content-transfer-encoding; bh=MsRP9AmUgsO6LO6ZzIhuul11FiLvd5Oob+dIVjLt/C0=; b=uESEX69ed4KGp4ZyAU/MMIDuTWOC6iInkQR9CG1aG8EI6v2UGmY9QRRkZuHM30ePqr gxdEW5RP06JzW5ZLbnXPQaKi/8E+F/w0I8P05Y15LYxB9vIgEb936bDeZaroZbAiYIWW 9FWbx0QGMwgDELWMCD0qSD2UIgYPhVPuUN5P3Jij3BYJgMXwOM+CR7yjh1GdKDgXnmes ZVyOHm7Jv47ILWnGrF4IEWGe2ezWIWXnJrEuRl69u3LCWoa8XLpsba7rBO5hCBgaA8jZ 1BAUF89Hbvi/2CIGO9YEBhGWn8WQb3jX+EbTE71nhqUlO4G0bSB72fWQytum86MtDZg9 P3vQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:organization:mime-version:content-transfer-encoding; bh=MsRP9AmUgsO6LO6ZzIhuul11FiLvd5Oob+dIVjLt/C0=; b=bGCOEr5S5BSaBQXHURCnA8vkBwOCtmvyI1QHDTy3pXIn+EQU1jkaVGVUdDMzJgItby IRm7ZhEkwSegHIR651ch2LmiV5TIbAmeHXcZCppJUJ9iFFuPS45WOih32h9so3KRd1c7 Tvtm4UyXyJUVp0dq7/4ZBsaW48L2YNToUDwLGwafgiTZjYIud4LYqJtc8RkvfgF/l35N Y50ftR0/dCeKR77y5qIoc2q9kbTaZcNwuOCR0QFaH/Ku5EunPrUaUAQbt3FKUr0CfNYs 8H7dtJmUE3Tye2CH+XOdaNaCLzCw79Rs/hloXEpVMLLIc9Wlp5Vkho4wsghaXdv5H2mJ 4KzA== X-Gm-Message-State: AD7BkJI0hE0QrIKMbTVtAORfGCMLcOy31QnXq/3OWJujLkz4htt46LplIgV1IPW+7gPPoA== X-Received: by 10.140.221.17 with SMTP id r17mr1502588qhb.61.1456796139962; Mon, 29 Feb 2016 17:35:39 -0800 (PST) Received: from ubuntu ([192.133.79.145]) by smtp.gmail.com with ESMTPSA id n48sm12098353qgd.38.2016.02.29.17.35.38 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 29 Feb 2016 17:35:38 -0800 (PST) In-Reply-To: X-Mailer: Evolution 3.16.5-1ubuntu3.1 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Tue, 2016-03-01 at 08:31 +0700, Duy Nguyen wrote: > On Tue, Mar 1, 2016 at 7:53 AM, David Turner < > dturner@twopensource.com> wrote: > > +Weaknesses: > > +----------- > > + > > +The reflog format is somewhat inefficient: a binary format could > > store > > +reflog date/time information in somewhat less space. > > This raises an interesting question. What if we want to change lmdb > format in future (e.g. to address this weakness)? Do we need some > sort > of versioning in lmdb database? I suppose you can always add "lmdb2" > backend that shares most of the code with current lmdb backend. Not > sure if that's what you had in mind though. The weakness of versioning inside the LMDB database is that in order to check the version, you need to already have LMDB. That's the argument for "lmdb2". I had sort of hoped that this version would be "good enough" that we could avoid modifying it. So maybe that means we ought to address the reflog format. But I'm not sure that it's that big a deal. What do you think?