"--tree-filter"和"--tree-filter"之间有什么区别?和"--index-filter"在"git filter-branch"中? [英] What is the difference between "--tree-filter" and "--index-filter" in the "git filter-branch"?

问题描述

我从这个地方学习树"和索引":通过示例学习Git内部原理

I learn "tree" and "index" from the this aritcle: Learning Git Internals by Example

但是当涉及到"git filter-branch"命令时，我不知道"--tree-filter"和"--index-filter"之间有什么区别.

but when it come to "git filter-branch" command, I don't know what is the difference between "--tree-filter" and "--index-filter".

推荐答案

简短的版本是--tree-filter将每个提交检出到一个临时目录中，运行您的filter命令，并根据现在的内容构建一个新的提交.临时目录；而--index-filter将每个提交复制到索引中，运行您的filter命令，并根据索引中的内容构建一个新的提交.

The short version is that --tree-filter checks out each commit into a temporary directory, runs your filter command, and builds a new commit from whatever is now in the temporary directory; while --index-filter copies each commit into the index, runs your filter command, and builds a new commit from whatever is now in the index.

将提交复制到索引要比检出提交快 ¹ .从索引构建提交比从目录构建提交要快.结果，使用索引过滤器比使用树过滤器快得多.不过，编写脚本并不容易.

Copying a commit to the index is much¹ faster than checking out the commit. Building a commit from the index is faster than building a commit from a directory. As a result, using the index filter is much faster than using the tree filter. It's not as easy to script for, though.

¹ 确切的速度差异取决于您的临时目录:内存中的文件系统比on-SSD上的文件系统快，后者比on-spining-media上的速度快，因此您可以获得更多如果您使用旋转媒体，则可以将树过滤器指向内存中的文件系统.但是即使那样，索引过滤器仍然更快.

¹The exact speed difference depends on your temporary directory: an in-memory file system is faster than an on-SSD file system which is faster than on-spinning-media, so you gain more if you're using spinning media than if you can point the tree filter to an in-memory file system. But even then the index filter is still faster.

在实际的磁盘上，我看到大约100倍(因此，需要2分钟的索引过滤器转换为需要3个小时以上的树形过滤器).

On actual disks, I've seen about a factor of 100 or so (hence an index filter that takes 2 minutes translates to a tree filter that takes 3+ hours).

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