我已经使用Subversion很多年了,在使用SourceSafe之后,我爱上了Subversion。结合TortoiseSVN,我真的无法想象它还能有什么更好的。

然而,越来越多的开发人员声称Subversion存在问题,我们应该转向新的分布式版本控制系统,比如Git。

Git如何改进Subversion?


当前回答

This is the wrong question to be asking. It's all too easy to focus on git's warts and formulate an argument about why subversion is ostensibly better, at least for some use cases. The fact that git was originally designed as a low-level version control construction set and has a baroque linux-developer-oriented interface makes it easier for the holy wars to gain traction and perceived legitimacy. Git proponents bang the drum with millions of workflow advantages, which svn guys proclaim unnecessary. Pretty soon the whole debate is framed as centralized vs distributed, which serves the interests of the enterprise svn tool community. These companies, which typically put out the most convincing articles about subversion's superiority in the enterprise, are dependent on the perceived insecurity of git and the enterprise-readiness of svn for the long-term success of their products.

但问题是:Subversion是架构的死胡同。

Whereas you can take git and build a centralized subversion replacement quite easily, despite being around for more than twice as long svn has never been able to get even basic merge-tracking working anywhere near as well as it does in git. One basic reason for this is the design decision to make branches the same as directories. I don't know why they went this way originally, it certainly makes partial checkouts very simple. Unfortunately it also makes it impossible to track history properly. Now obviously you are supposed to use subversion repository layout conventions to separate branches from regular directories, and svn uses some heuristics to make things work for the daily use cases. But all this is just papering over a very poor and limiting low-level design decision. Being able to a do a repository-wise diff (rather than directory-wise diff) is basic and critical functionality for a version control system, and greatly simplifies the internals, making it possible to build smarter and useful features on top of it. You can see in the amount of effort that has been put into extending subversion, and yet how far behind it is from the current crop of modern VCSes in terms of fundamental operations like merge resolution.

现在,对于那些仍然相信Subversion在可预见的未来足够优秀的人,我有一个发自内心的不可知论的建议:

Subversion永远不会赶上从RCS和CVS的错误中吸取教训的新型vcs;这在技术上是不可能的,除非他们从头开始重新配置存储库模型,但这样就不是真正的SVN了,不是吗?不管你认为自己有多不具备现代VCS的能力,你的无知也无法保护你远离Subversion的陷阱,其中许多情况在其他系统中是不可能或很容易解决的。

It is extremely rare that the technical inferiority of a solution is so clear-cut as it is with svn, certainly I would never state such an opinion about win-vs-linux or emacs-vs-vi, but in this case it is so clearcut, and source control is such a fundamental tool in the developer's arsenal, that I feel it must be stated unequivocally. Regardless of the requirement to use svn for organizational reasons, I implore all svn users not to let their logical mind construct a false belief that more modern VCSes are only useful for large open-source projects. Regardless of the nature of your development work, if you are a programmer, you will be a more effective programmer if you learn how to use better-designed VCSes, whether it be Git, Mercurial, Darcs, or many others.

其他回答

它是分布的。基准测试表明,它的速度要快得多(考虑到它的分布式性质,像diffs和log这样的操作都是本地的,所以在这种情况下,它当然要快得多),而且工作文件夹也更小(这仍然让我大吃一惊)。

当您使用subversion或任何其他客户端/服务器版本控制系统时,您实际上是通过签出版本在您的机器上创建工作副本。这代表了存储库外观的时间快照。通过更新更新工作副本,通过提交更新存储库。

使用分布式版本控制,您没有快照,而是拥有整个代码库。想要一个3个月大的版本吗?没问题,3个月前的版本还在你的电脑上。这不仅意味着速度更快,而且如果您与中央服务器断开连接,您仍然可以执行许多您习惯的操作。换句话说,您不仅拥有给定修订的快照,而且拥有整个代码库。

您可能认为Git会占用大量硬盘空间,但从我看到的几个基准测试来看,它实际上占用的空间更少。不要问我怎么做。我的意思是,它是由莱纳斯构建的,我猜他对文件系统略知一二。

其他的回答很好地解释了Git的核心特性(这些特性非常棒)。但是还有很多小方法可以让Git表现得更好,并帮助我的生活更加理智。以下是一些小细节:

Git has a 'clean' command. SVN desperately needs this command, considering how frequently it will dump extra files on your disk. Git has the 'bisect' command. It's nice. SVN creates .svn directories in every single folder (Git only creates one .git directory). Every script you write, and every grep you do, will need to be written to ignore these .svn directories. You also need an entire command ("svn export") just to get a sane copy of your files. In SVN, each file & folder can come from a different revision or branch. At first, it sounds nice to have this freedom. But what this actually means is that there is a million different ways for your local checkout to be completely screwed up. (for example, if "svn switch" fails halfway through, or if you enter a command wrong). And the worst part is: if you ever get into a situation where some of your files are coming from one place, and some of them from another, the "svn status" will tell you that everything is normal. You'll need to do "svn info" on each file/directory to discover how weird things are. If "git status" tells you that things are normal, then you can trust that things really are normal. You have to tell SVN whenever you move or delete something. Git will just figure it out. Ignore semantics are easier in Git. If you ignore a pattern (such as *.pyc), it will be ignored for all subdirectories. (But if you really want to ignore something for just one directory, you can). With SVN, it seems that there is no easy way to ignore a pattern across all subdirectories. Another item involving ignore files. Git makes it possible to have "private" ignore settings (using the file .git/info/exclude), which won't affect anyone else.

为什么我认为Subversion比Git好(至少对于我所从事的项目来说),主要是因为它的可用性和更简单的工作流程:

http://www.databasesandlife.com/why-subversion-is-better-than-git/

我认为Subversion很好。直到你开始合并…或者做任何复杂的事情。或者做任何Subversion认为复杂的事情(比如查询哪些分支弄乱了特定的文件,更改实际上来自哪里,检测复制和粘贴,等等)…

我不同意获胜的答案,我认为GIT的主要好处是离线工作——它当然有用,但它更像是我的用例的额外功能。SVK也可以离线工作,对我来说,把我的学习时间投入到哪一个是没有问题的)。

只是它非常强大、快速,而且——在习惯了这些概念之后——非常有用(是的,在这个意义上:用户友好)。

有关合并故事的更多细节,请参见: 使用git-svn(或类似)*只是*帮助svn合并?

我非常喜欢能够在Git中管理源代码的本地分支,而不会混淆中央存储库的水。在许多情况下,我将从Subversion服务器签出代码并运行本地Git存储库,只是为了能够做到这一点。初始化Git存储库不会因为到处都是烦人的.svn文件夹而污染文件系统,这一点也很棒。

至于Windows工具的支持,TortoiseGit处理基本的很好,但我仍然喜欢命令行,除非我想查看日志。我真的很喜欢Tortoise{Git|SVN}在读取提交日志时的帮助方式。