Re: two questions about the format of loose object

Junio C Hamano wrote:

Liu Yubao [off-list ref] writes:


A hint for understanding why loose objects are compressed is that
packfiles were invented much later in the history of git.

These are both good questions, and it might have made a difference if they
were posed in early April 2005.

At this point, the plain and clear answer to both of these "Why not"
questions is "because that is the way it is and it is costly to change
them now in thousands of repositories people use every day."

In other words, it is not interesting anymore to raise these questions
now, especially as a suggestion to change the system, unless they are
accompanied by arguments that convinces everybody that the cost of such a
change outweighs the benefits, and a clear transition plans how to upgrade
everybody's existing repositories without any pain.

Thanks for your explanation, but I doubt if it's too costly to change the
format of loose object, after all this doesn't change the format of pack
file and affect git-pull/fetch of old git client. 

I ask the "why not" questions because I doubt if I miss some technical points
that the change isn't worth at all in fact.

If no severe technical problem will occur, I think it's worth breaking
*forward* compatibility for better performance and I'm willing to implement
it.

Some cons and pros.

cons:

* old git client can't read loose objects in new format
  (People degrade git rarely and old git can read pack files
   generated by new git, so it's not a big problem)

pros:

* avoid compressing and uncompressing loose objects that are likely
  frequently used when you are coding/merging
* share loose objects among multipe git processes
* the new code path is simpler although we will have more code paths for
  compatibility


Best regards,

Liu Yubao