CODEWITHSUNDEEP
git
Ashish
Ashish

Reputation: 14707

Where does git store blob object?

I understand that git compress the file and then calculate the SHA1 and store that in .git/objects/ and we can see the content using git cat-file -p 'sha1' but I am interested to know where does git store the compressed blob objects.

as mentioned in the following post

http://gitready.com/beginner/2009/02/17/how-git-stores-your-data.html

Update I can only see SHA1 in .git/objects which I think are reference to the actual blob rather than blob

Upvotes: 2

Views: 1332

Answers (1)

bames53
bames53

Reputation: 88155

I understand that git compress the file and then calculate the SHA1

Git computes the SHA1 hash of the uncompressed file, Then it compresses the data and stores it in .git/objects, using the SHA1 as the filename.

Example:

1. create a test repository

$ mkdir tmp
$ cd tmp
$ git init .
Initialized empty Git repository in /tmp/.git/

2. add a test file

$ echo 'hello, world' > hello.txt
$ git add hello.txt
$ git commit -m "Initial commit"
[master (root-commit) 951d5cc] Initial commit
 1 file changed, 1 insertion(+)
 create mode 100644 hello.txt

3. display the test file's content in the .git/objects directory

$ git hash-object hello.txt
4b5fa63702dd96796042e92787f464e28f09f17d
$ cat .git/objects/4b/5fa63702dd96796042e92787f464e28f09f17d
xKOR04fQ(I??
$ python -c "import zlib,sys;print repr(zlib.decompress(sys.stdin.read()))" < .git/objects/4b/5fa63702dd96796042e92787f464e28f09f17d
'blob 13\x00hello, world\n'

The script in the last line is from this answer.

As you can see, the file content in .git/objects is not viewable directly, cat displays it only as xKOR04fQ(I??. The file is also not stored in a standard container for compressed data, but using zlib you can decrompress the raw data. The stored file also contains git metadata about the content: the type of git object and the length of the content. But the data is clearly stored right there in .git/objects:

blob 13\x00hello, world\n

Upvotes: 8

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