Packfiles and compression in Git - Step-by-Step Execution

Process Flow - Packfiles and compression

Start: Git objects created

↓

Objects stored loose

↓

Run git gc or pack-objects

↓

Objects compressed into packfile

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Packfile stored in .git/objects/pack

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Git uses packfile for faster access

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New objects added later -> loose or packed

Git collects loose objects and compresses them into packfiles to save space and speed up operations.

Execution Sample

Git

git gc
# or
git repack -a -d
# pack loose objects into compressed packfile

This command compresses loose git objects into a packfile to optimize storage.

Process Table

Step	Action	Objects State	Result
1	Create commits, blobs, trees	Loose objects created	Objects stored individually
2	Run git gc	Loose objects present	Git starts packing process
3	Pack objects	Objects compressed	Packfile created in .git/objects/pack
4	Delete loose objects	Loose objects removed	Only packfile remains
5	Git uses packfile	Packfile used for object retrieval	Faster access and less disk space
6	New objects created	New loose objects	Will be packed later

💡 Packing completes, loose objects compressed and removed, packfile used for efficiency

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	After Step 6
Loose Objects	0	Many	Being packed	0	Some new ones
Packfile	None	None	Created	Exists	Exists
Disk Space Used	Low	High (loose objects)	Lower (compressed)	Lowest	Slightly higher

Key Moments - 3 Insights

Why do loose objects exist before packing?

Loose objects are created individually when you commit or add files; packing happens later during git gc or repack (see execution_table step 1 and 2).

What happens to loose objects after packing?

They are deleted to save space because their data is now inside the packfile (see execution_table step 4).

Why does Git still create loose objects after packing?

New changes create new loose objects; packing is a periodic cleanup, not continuous (see execution_table step 6).

Visual Quiz - 3 Questions

Look at the execution table, at which step are loose objects deleted?

A Step 4

B Step 3

C Step 5

D Step 6

💡 Hint

Check the 'Objects State' column for when loose objects become zero.

According to the variable tracker, what happens to disk space after packing?

A Disk space increases

B Disk space decreases

C Disk space stays the same

D Disk space is zero

💡 Hint

Look at 'Disk Space Used' values from 'After Step 2' to 'After Step 4'.

If you create new commits after packing, what happens to objects?

A They are immediately packed

B They overwrite the packfile

C They remain loose until next packing

D They are deleted

💡 Hint

See execution_table step 6 and variable tracker for loose objects after new commits.

Concept Snapshot

Git stores objects as loose files initially.
Running 'git gc' or 'git repack' compresses these into packfiles.
Packfiles save disk space and speed up Git operations.
Loose objects are deleted after packing.
New objects are loose until next packing.

Full Transcript

Git creates objects like commits and files as loose files first. When you run 'git gc' or 'git repack', Git compresses these loose objects into a packfile stored in the .git/objects/pack directory. This packfile uses less disk space and makes Git faster. After packing, the loose objects are deleted because their data is now inside the packfile. However, new commits or changes create new loose objects again, which will be packed later during the next cleanup. This process helps Git manage storage efficiently while keeping performance high.