Re: [RFC] Cache negative delta pairs

On Thu, 29 Jun 2006, Nicolas Pitre wrote:

And this can be pushed even further by just including the sha1 of the 
victim object inside the list of objects therefore computing a hash of 
all objects (the victim and the window) for which no delta results. The 
cache is therefore a list of hash values corresponding to bad 
victim+window combinations.

So given my GIT repository such a cache would be 7610 * 40 = 304400 
bytes if we stick to the full 40 bytes of sha1 to hash bad combinations.

Correction: the 40 bytes figure is for _ascii_ representation of sha1 
values.  The cache doesn't need ascii and therefore this number can be 
reduced by half.


Nicolas