[MERGE][0.15] Speed up 'bzr status' in xml trees

[John Arbash Meinel]

Aaron Bentley wrote:
> John Arbash Meinel wrote:
>>> You realize that the cached-basis code is designed to be robust, right?
>>>    You can put garbage there, or anything you like, and it won't fall over.
> 
>> Oh, I understand you can put garbage there. But when you are trying to
>> benchmark the performance of 'bzr status' for the last 8 revisions of
>> bzr, it is nice when you don't have to do a full add+commit just to
>> regenerate the basis-inventory-cache.
> 
> Pull will also do it.  Anything that does wt.set_last_revision().

Well, except I have no new revisions to pull. I'm just going to write a
plugin which triggers it.

> 
>> Anyway, format 5 would be great for compatibility, I'm not sure how we
>> would jump to format 7 when we actually need it. Since WT4 actually does
>> support things like nested trees, we probably should stick with format 7.
> 
> But WT4 doesn't store basis this way, and WT3 doesn't support nested trees.
> 
> Aaron

Yeah, I realized that after I sent it. :)

I think the other thing for 6 versus 5 was tree-root support. But IIRC
WT3 doesn't really support that either.

John
=:->