Re: Calculating tree nodes
- From
- David Tweed <david.tweed@gmail.com>
- Date
- Sep 4, 2007, 04:19 UTC
- Message-ID
- <e1dab3980709032119r381f7a91ia84ba09039c21be1@mail.gmail.com>
- In-Reply-To
- <9e4733910709032026s7f94eed9h25d5165840cc38d2@mail.gmail.com>
On 9/4/07, Jon Smirl <jonsmirl@gmail.com> wrote:
> Git has picked up the hierarchical storage scheme since it was built > on a hierarchical file system.
FWIW my memory is that initial git used path-to-blob lists (as you're describing but without delta-ing) and tree nodes were added after a couple of weeks, the motivation _at the time_ being they were a natural way to dramatically reduce the size of repos.
One of the nice things about tree nodes is that for doing a diff between versions you can, to overwhelming probability, decide equality/inequality of two arbitrarily deep and complicated subtrees by comparing 40 characters, regardless of how remote and convoluted their common ancestry. With delta chains don't you end up having to trace back to a common "entry" in the history? (Of course, I don't know how packs affect this - presumably there's some delta chasing to get to the bare objects as well.)
-- cheers, dave tweed__________________________ david.tweed@gmail.com Rm 124, School of Systems Engineering, University of Reading. "we had no idea that when we added templates we were adding a Turing- complete compile-time language." -- C++ standardisation committee