GiH GiH - 1 month ago 7
Git Question

In git, what is the difference between merge --squash and rebase?

I'm new to git and I'm trying to understand the difference between a squash and a rebase. As I understand it you perform a squash when doing a rebase.

Answer

Both git merge --squash and git rebase --interactive can produce a "squashed" commit.
But they serve different purposes.

will produce a squashed commit on the destination branch, without marking any merge relationship.
This is useful if you want to throw away the source branch completely, going from (schema taken from SO question):

 git checkout stable

      X                   stable
     /                   
a---b---c---d---e---f---g tmp

to:

git merge --squash -m "squash tmp" tmp

      X-------------------G stable
     /                   
a---b---c---d---e---f---g tmp

and then deleting tmp branch.

replays some or all of your commits on a new base, allowing you to squash (or more recently "fix up", see this SO question), going directly to:

git checkout tmp
git rebase -i stable

      stable
      X-------------------G tmp
     /                     
a---b

If you choose to squash all commits of tmp (but, contrary to merge --squash, you can choose to replay some, and squashing others).

So the differences are:

  • merge does not touch your source branch (tmp here) and creates a single commit where you want.
  • rebase allows you to go on on the same source branch (still tmp) with:
    • a new base
    • a cleaner history
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