From: A Large Angry SCM Date: Thu, 07 Sep 2006 17:22:54 GMT Subject: Re: A look at some alternative PACK file encodings Message-ID: <4500556E.7070803@gmail.com> In-Reply-To: <9e4733910609070557jd8cfc57nd4f7a8973b69f6ed@mail.gmail.com> Jon Smirl wrote: > On 7 Sep 2006 05:07:56 -0400, linux@horizon.com wrote: >> > Support for 'thin' packs would pretty much require mixing IDs and >> > (relative) offsets in the same pack file. >> >> An alternative would be to create a small "placeholder" object that >> just gives an ID, then refer to it by offset. >> >> That would avoid the need for an id/offset bit with every offset, >> and possibly save more space if the same object was referenced >> multiple times. >> >> And it just seems simpler. > > There are 2 million objects in the Mozilla pack. This table would take: > 2M * (20b (sha) + 10b(object index/overhead) = 60MB > This 60MB is pretty much incompressible and increases download time. > > Much better if storage of the sha1s can be totally eliminated and > replaced by something smaller. Alternatively this map could be > stripped for transmission and rebuilt locally. > You've lost me. What are you attempting to do again?