Quick command to count commits

Quick command to count commits

[Henk]

Hi,

For GitExtensions (windows git ui) I need a command to count all commits. I
now use this command:
git.cmd rev-list --all --abbrev-commit | wc -l

This works perfect but its very slow in big repositories. Is there a faster
way to count the commits?

Henk
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Re: Quick command to count commits

[Shawn O. Pearce]

Henk <henk_westhuis@hotmail.com> wrote:
> For GitExtensions (windows git ui) I need a command to count all commits. I
> now use this command:
> git.cmd rev-list --all --abbrev-commit | wc -l
> 
> This works perfect but its very slow in big repositories. Is there a faster
> way to count the commits?

No.  But drop the --abbrev-commit flag, abbreviating the object ids
would take longer than just dumping the full 40 bytes to stdout.
It requires a scan of parts of the object database for every commit
to determine what is a unique abbreviation.

This isn't a very common operation.  Its expensive to do, as you
can see.  What's the reason for supplying it, and needing it so
quickly?  Nobody really cares how many commits are in their history,
unless they are trying to produce stats to describe how big their
repository is.  In which case the size of the .git/objects/pack
*.pack and *.idx files is much more relevant, especially the .idx
files as it gives a really quick estimate on the number of total
objects in the repository.

-- 
Shawn.

Re: Quick command to count commits

[Linus Torvalds]

On Tue, 6 Jan 2009, Henk wrote:
>
> For GitExtensions (windows git ui) I need a command to count all commits. I
> now use this command:
> git.cmd rev-list --all --abbrev-commit | wc -l
> 
> This works perfect but its very slow in big repositories. Is there a faster
> way to count the commits?

Nope. Possibly drop the --abbrev-commit part, but it's not going to hurt 
_that_ much, and maybe avoiding piping the data can be a win in some 
cases.

Basically, to get commit counts, you need to traverse the whole history, 
or at least cache it. So the only way to speed things up is

 - make sure your repository is well-packed. That will speed things up by 
   an absolutely huge amount, if they weren't well-packed before. Just a 
   single large pack-file, not lots of small packs, and not lots of loose 
   objects.

 - you can certainly cache it. Just index by the sha1sum of all the heads, 
   and you have a great cache. Just keep a single entry. So _if_ the 
   repository seldom changes, and you do this a lot, you'll at least only 
   pay the price once.

IOW, do something like this:

	#!/bin/sh
	revs=$(git rev-parse --all)
	index=$(echo "$revs" | sha1sum | cut -d' ' -f1)
	cached=$(cat .git/commit_nr_cache)
	cached_index=$(echo "$cached" | cut -d' ' -f1)
	if [ "$index" == "$cached_index" ]; then
		echo "$cached" | cut -d' ' -f2
		exit
	fi
	nr=$(git rev-list $revs | wc -l)
	echo "$index $nr" > .git/commit_nr_cache
	echo $nr

and you now have a stupid single-entry cache.

Totally untested. You'll need to do _some_ work yourself ;)

		Linus

Re: Quick command to count commits

[Ted Pavlic]

I doubt it's going to be much faster, but it's easier to type

	git shortlog -s|numsum

I *think* that should give you the same number, and it forces git to do 
more of the counting (rather than wc).

Strangely, on one repo that I test that on, I get slightly different 
numbers from that command and yours. I'm not quite sure why (I guess 
shortlog doesn't count all commits?).

--Ted

On 1/6/09 1:51 PM, Henk wrote:
>
> Hi,
>
> For GitExtensions (windows git ui) I need a command to count all commits. I
> now use this command:
> git.cmd rev-list --all --abbrev-commit | wc -l
>
> This works perfect but its very slow in big repositories. Is there a faster
> way to count the commits?
>
> Henk

-- 
Ted Pavlic <ted@tedpavlic.com>