Difference between revisions of "Git"
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All the different objects in Git - individual files, entire directory trees, commits and other things - are stored in a repository-wide central store. Each object is identified by computing a SHA-1 hash, which is a function of only the object's contents. |
All the different objects in Git - individual files, entire directory trees, commits and other things - are stored in a repository-wide central store. Each object is identified by computing a SHA-1 hash, which is a function of only the object's contents. |
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| + | === But... doesn't that mean that when I change a single line in a file, a whole new copy is stored? === |
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| + | Yes. |
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| + | However, every once in a while, git compacts files that are similar together into Packfiles, by storing only their diffs. [TO BE EXPANDED?] |
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=== Garbage collection and <tt>git reflog</tt> === |
=== Garbage collection and <tt>git reflog</tt> === |
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Revision as of 20:46, 6 September 2012
WORK IN PROGRESS
This page aims to introduce the concepts behind Git in a "Haskell way".
The DAG
TODO
Branches and tags
TODO
Objects
Kinds of objects
TODO
The object store
All the different objects in Git - individual files, entire directory trees, commits and other things - are stored in a repository-wide central store. Each object is identified by computing a SHA-1 hash, which is a function of only the object's contents.
But... doesn't that mean that when I change a single line in a file, a whole new copy is stored?
Yes.
However, every once in a while, git compacts files that are similar together into Packfiles, by storing only their diffs. [TO BE EXPANDED?]
Garbage collection and git reflog
When objects are not reachable from any root (like a branch reference), they become dangling and are subject to garbage collection. However, garbage collection does not kick in immediately.
When making a mistake, it is often helpful to look at commit objects by date independent of whether they are reachable, in order to be able to restore them. You can use git reflog for that.