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|
.Dd June 9, 2021
.Dt SPARSE-CHECKOUT 7
.Os "Causal Agency"
.
.Sh NAME
.Nm Sparse Checkout
.Nd a cool git feature
.
.Sh DESCRIPTION
I was going to write a post about
.Xr git-subtree 1
(and I still plan to!)
but while talking about it
with a friend
I came across another command:
.Xr git-sparse-checkout 1 .
I got pretty excited because
I already had a use case for it.
.
.Pp
.Xr git-sparse-checkout 1
does pretty much what it sounds like.
It lets you only have
a subset of files in the repository actually
.Dq checked out .
This is really useful
for huge respositories
where you are only interested in
some part of it.
Any operation touching the working tree
is much faster because
it can skip all the files you don't care about.
.
.Pp
My use case is with the
.Fx
.Xr ports 7
tree,
which recently moved to git
and contains almost 14 thousand files.
Working with the whole repository
was super painful.
.Xr git-status 1 ,
which I run as a habit
when my shell is idle,
would take dozens of seconds
to check the whole working tree
and report back.
(I didn't get any real time measurements
before enabling
.Xr git-sparse-checkout 1 ,
and I'm not about to disable it now,
since it'd have to check out
all those files again.)
I'm only actually working on
a small handful of ports,
so all that work is wasted.
Time to turn on sparse checkout:
.Bd -literal -offset indent
git sparse-checkout init --cone
.Ed
.
.Pp
The
.Fl \-cone
option here
(which I keep reading as
.Dq clone
because it's git)
restricts the kinds of patterns
you can use to select files to check out,
but makes the calculation more efficient.
Basically it means you can only select
paths along with everything below them,
which I think is pretty much
always what you want anyway.
Enabling sparse checkout
can take quite a while
because it has to do a lot of un-checking-out.
I should mention
that you can pass
.Fl \-sparse
to
.Xr git-clone 1
to avoid ever checking out
the whole tree.
.
.Pp
The default selection when you run
.Cm init
is to check out all the files
at the root of the repository,
but none of the subdirectories.
For
.Xr ports 7 ,
I also want to check out
the shared scripts and Makefiles:
.Bd -literal -offset indent
git sparse-checkout add Keywords Mk Templates Tools
.Ed
.
.Pp
And then I can selectively check out
just the ports I'm working on:
.Bd -literal -offset indent
git sparse-checkout add irc/catgirl irc/pounce
.Ed
.
.Pp
After enabling sparse checkout,
.Xr git-status 1
takes what I'd call
a normal amount of time.
I also did this on
a couple-weeks-out-of-date copy of the
.Xr ports 7
tree,
and when I ran
.Xr git-pull 1
it was also really quick,
because it didn't have to bother
updating all those files
I'm not interested in.
It still downloads all the git objects,
of course,
and you can just add any new paths you need
to the sparse checkout list.
My disk usage also went down
by about a gigabyte.
.
.Pp
I'm super pleased to discover this part of git,
because it makes working with huge
and/or monorepo-style repositories
so much more feasible!
You can see how I came across it,
since
.Xr git-subtree 1
is also a useful tool for monorepos.
Stay tuned for that post,
I guess :)
.
.Sh AUTHORS
.An june Aq Mt june@causal.agency
|