Re: [PATCHv4 08/12] Teach the notes lookup code to parse notes trees with various fanout schemes

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Hi,

On Fri, 28 Aug 2009, Johan Herland wrote:

> On Thursday 27 August 2009, Junio C Hamano wrote:
> > "Shawn O. Pearce" <spearce@xxxxxxxxxxx> writes:
> > > Yea, it was me.  I still think it might be a useful idea, since it 
> > > allows you better density of loading notes when parsing the recent 
> > > commits.  In theory the last 256 commits can easly be in each of the 
> > > 2/ fanout buckets, making 2/38 pointless for reducing the search 
> > > space.  Commit date on the other hand can probably force all of them 
> > > into the same bucket, making it easy to have the last 256 commits in 
> > > cache, from a single bucket.
> > >
> > > But I thought you shot it down, by saying that we also wanted to 
> > > support notes on blobs.  I happen to see no value in a note on a 
> > > blob, a blob alone doesn't make much sense without at least an 
> > > annotated tag or commit to provide it some named context, and the 
> > > latter two have dates.
> >
> > Yeah, and in this thread everybody seems to be talking about commits 
> > so I think it is fine to limit notes only to commits.
> 
> Agreed. I'm starting to come around to the idea of storing them in 
> subtrees based on commit dates. For one, you don't have multiple notes 
> for one commit in the same notes tree. Also, the common-case access 
> pattern seems tempting.
> 
> Dscho: Were there other problems with the date-based approach other than 
> not supporting notes on trees and blobs?

It emphasized an implementation detail too much for my liking.

And I would rather have some flexibility in the code as to _when_ it fans 
out and when not.

So I can easily imagine a full repository which has only, say, 5 notes.  
Why not have a single tree for all of those?

And I can easily imagine a repository that has a daily note generated by 
an automatic build, and no other notes.  The date-based fan-out just 
wastes our time here, and even hurts performance.

Ciao,
Dscho

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