Re: What's cooking in git.git (Jul 2009, #01; Mon, 06)

Junio C Hamano [off-list ref] wrote:

"Shawn O. Pearce" [off-list ref] writes:

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* jh/notes (Sat May 16 13:44:17 2009 +0200) 5 commits

I was thinking about this the other day.  We could use a hash of
the commit timestamp as the top level directory.  E.g. if we take
the commit time of the commit and convert it to a date string,
we could make the note path e.g.:

  YYYY/MM/COMMITSHA1

Is the idea to make the tree object we need to scan for that particular
SHA-1 hash smaller?

No, the idea was to avoid needing to create a massive hash of all
commit notes just to answer `git log -10` on the current branch.
I remember that was a concern last time we were talking about this.
By putting the notes under a timestamped path we can scan only a
small percentage of the notes before we have sufficient data to
output the first few commits.

If so, I am not sure how it would help over another approach of say taking
the first four hexdigits from the SHA-1 to use as the initial fan-out
YYYY, then two hexdigits for the secondary fan-out MM.

See above, the idea is to avoid scanning all notes at once on
startup.  SHA-1 is bad at this as a fanout because it is too good
at uniform distribution of the names.
 

But probably I am missing something.

Besides, trees and blobs cannot be annotated with that approach.

True.  But I didn't realize that was a goal.  :-|

-- 
Shawn.