| From: | Martin Langhoff <martin(at)catalyst(dot)net(dot)nz> |
|---|---|
| To: | "Jim C(dot) Nasby" <jim(at)nasby(dot)net> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Aidan Van Dyk <aidan(at)highrise(dot)ca>, "Florian G(dot) Pflug" <fgp(at)phlo(dot)org>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Hacking on PostgreSQL via GIT |
| Date: | 2007-04-18 22:07:08 |
| Message-ID: | 4626968C.30208@catalyst.net.nz |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Jim C. Nasby wrote:
> Then how do you tell what version a file is if it's outside of a
> checkout?
It's trivial for git to answer that - the file will either be pristine,
and then we can just scan for the matching SHA1, or modified, and we can
scan (taking a weee bit more time) which are the "closest matches" in
your history, in what branches and commits.
The actual scripting for this isn't written just yet -- Linus posted a
proof-of-concept shell implementation along the lines of
git rev-list --no-merges --full-history v0.5..v0.7 --
src/widget/widget.c > rev-list
best_commit=none
best=1000000
while read commit
do
git cat-file blob "$commit:src/widget/widget.c" > tmpfile
lines=$(diff reference-file tmpfile | wc -l)
if [ "$lines" -lt "$best" ]
then
echo Best so far: $commit $lines
best=$lines
fi
done < rev-list
and it's fast. One of the good properties of this is that you can ask
for a range of your history (v0.5 to v0.7 in the example) and an exact
path (src/widget/widget.c) but you can also say --all (meaning "in all
branches") and a handwavy "over there", like src. And git will take an
extra second or two on a large repo, but tell you about all the good
candidates across the branches.
Metadata is metadata, and we can fish it out of the SCM easily - and
data is data, and it's silly to pollute it with metadata that is mostly
incidental.
If I find time today I'll post to the git list a cleaned up version of
Linus' shell script as
git-findclosestmatch <head or range or --all> path/to/scan/ \
randomfile.c
cheers,
m
--
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Martin @ Catalyst .Net .NZ Ltd, PO Box 11-053, Manners St, Wellington
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Make things as simple as possible, but no simpler - Einstein
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