How does Git know which Index blob to add to a tree?

Posted by drozzy on Stack Overflow See other posts from Stack Overflow or by drozzy
Published on 2010-04-27T14:23:44Z Indexed on 2010/04/27 16:13 UTC
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git

In Pro Git Ch9 the author says:

Git normally creates a tree by taking the state of your staging area or index and writing a tree object from it.

My question is how does git know which of two consequitive index entries to create the Tree object from?

For example:

$ echo 'First change' > one.txt
$ git add one.txt 
$ find .git/objects -type f
.git/objects/1f/755a7fffe4   //first index entry

$ echo 'Second change' > one.txt
$ git add one.txt
$ find .git/objects -type f
.git/objects/2d/234asdf2   //second index entry

$ git commit -a -m "Initial commit"
$ git cat-file master^{tree}
100644 blob 2d234asdf2 one.txt  //How did it know not to take 1f755??

Does it just look at the blob timestamps? Also - what happens to the first blob created - no one is referencing it. Does it just get destroyed or forgotten?

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Developer IT

How does Git know which Index blob to add to a tree? - Developer IT

How does Git know which Index blob to add to a tree?

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