How Git stores objects - Visual Walkthrough

Process Flow - How Git stores objects

Create file or change

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Generate SHA-1 hash of content

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Compress content with zlib

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Store compressed object in .git/objects/xx/

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Index object by SHA-1 prefix

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Use object in commits, trees, blobs

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Retrieve by SHA-1 when needed

Git takes file content, creates a unique hash, compresses it, and stores it in a special folder indexed by that hash.

Execution Sample

Git

echo "Hello" > file.txt
sha1=$(git hash-object file.txt)
mkdir -p .git/objects/${sha1:0:2}
cp file.txt .git/objects/${sha1:0:2}/${sha1:2}

This simulates how Git hashes a file and stores it in the objects folder by splitting the SHA-1 hash.

Process Table

Step	Action	Input/State	Output/State Change
1	Create file	file.txt content: 'Hello'	File created with content 'Hello'
2	Generate SHA-1 hash	Content 'Hello'	SHA-1 hash: e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
3	Compress content	Content 'Hello'	Compressed data ready for storage
4	Create directory	.git/objects/e6	Directory created for first 2 chars of hash
5	Store object	Compressed data	Stored in .git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391
6	Index object	Stored object	Object indexed by SHA-1 for retrieval
7	Use object	Object indexed	Used in commits, trees, blobs
8	Retrieve object	SHA-1 hash	Original content retrieved by hash

💡 Process ends after object is stored and indexed for retrieval by SHA-1 hash

Status Tracker

Variable	Start	After Step 2	After Step 5	Final
file.txt content	none	'Hello'	'Hello'	'Hello'
SHA-1 hash	none	e69de29bb2d1d6434b8b29ae775ad8c2e48c5391	e69de29bb2d1d6434b8b29ae775ad8c2e48c5391	e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
Compressed data	none	none	compressed 'Hello'	compressed 'Hello'
Storage path	none	none	.git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391	.git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391

Key Moments - 3 Insights

Why does Git split the SHA-1 hash into two parts for storage?

Git uses the first two characters of the SHA-1 hash as a folder name to avoid too many files in one directory, making storage efficient and fast (see Step 4 and 5 in execution_table).

Is the stored object the original file content?

No, Git compresses the content before storing it to save space, so the stored object is compressed data (see Step 3 and 5 in execution_table).

How does Git find the object later?

Git uses the full SHA-1 hash to locate the object by combining the folder (first 2 chars) and file name (remaining chars) to retrieve and decompress it (see Step 8 in execution_table).

Visual Quiz - 3 Questions

Look at the execution table, what is the SHA-1 hash generated at Step 2?

A 9de29bb2d1d6434b8b29ae775ad8c2e48c5391e6

B e69de29bb2d1d6434b8b29ae775ad8c2e48c5391

C Hello

D compressed 'Hello'

💡 Hint

Check the 'Output/State Change' column at Step 2 in the execution_table.

At which step is the object compressed before storage?

A Step 2

B Step 5

C Step 3

D Step 7

💡 Hint

Look at the 'Action' column describing compression in the execution_table.

If the SHA-1 hash started with 'ab', where would Git store the object?

A .git/objects/ab/...

B .git/objects/e6/...

C .git/objects/ba/...

D .git/objects/aa/...

💡 Hint

Refer to Step 4 and 5 in execution_table about directory naming from SHA-1 prefix.

Concept Snapshot

Git stores objects by:
- Creating a SHA-1 hash of file content
- Compressing the content
- Splitting hash: first 2 chars as folder, rest as filename
- Saving compressed object in .git/objects/
- Using hash to retrieve content later

Full Transcript

Git stores data by first creating a unique SHA-1 hash from the file content. This hash acts like a fingerprint. Then Git compresses the content to save space. It splits the hash into two parts: the first two characters become a folder name inside .git/objects, and the remaining characters become the file name inside that folder. The compressed content is saved there. Later, Git uses the full hash to find and decompress the object when needed. This process helps Git store data efficiently and retrieve it quickly.