On Thu, Jan 31, 2013 at 6:06 PM, Duy Nguyen <pclo...@gmail.com> wrote:
> On Wed, Jan 30, 2013 at 09:16:29PM +0700, Duy Nguyen wrote:
>> Perhaps we could store abbrev sha-1 instead of full sha-1. Nice
>> space/time trade-off.
> Following the on-disk format experiment yesterday, I changed the
> format to:
> - a list a _short_ SHA-1 of cached commits
> The length of SHA-1 is chosen to be able to unambiguously identify any
> cached commits. Full SHA-1 check is done after to catch false
> positives. For linux-2.6, SHA-1 length is 6 bytes, git and many
> moderate-sized projects are 4 bytes.
And if we are going to create index v3, the same trick could be used
for the sha-1 table in the index. We use the short sha-1 table for
binary search and put the rest of sha-1 in a following table (just
like file offset table). The advantage is a denser search space, about
1/4-1/3 the size of full sha-1 table.
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