On 28.02.2012 00:20, Paul Burba wrote: > On Thu, Feb 16, 2012 at 12:31 PM, Branko Čibej <br...@apache.org> wrote: >> On 16.02.2012 16:46, C. Michael Pilato wrote: >>> On 02/16/2012 05:50 AM, Branko Čibej wrote: >>>> On 15.02.2012 21:18, Greg Stein wrote: >>>>> And thinking on that: how does the client do inheritance in a >>>>> mixed-revision working copy? D@10 inherits props from P, but the >>>>> client has P@5. If there are changes in P@7, then the inherited >>>>> properties a likely wrong for D@10. >>>> Reading this thread really makes me wonder a bit... How can anyone even >>>> contemplate implementing inheritable properties on the client side? A >>>> server-side implementation of (strictly versioned!) inheritable props >>>> would not require any new logic on the client, and it's the only way to >>>> make such a thing work without expecting weird behaviour with different >>>> client versions. I'd have thought that the mergeinfo saga would have >>>> been enough of a reality check. >>>> >>>> Regarding upwards searches and "bounded reads" ... anyone who believes >>>> reading a datastore is cheap should try to write a fast, data-intensive >>>> GAE application. :) >>>> >>>> IOW, I completely agree with Bill Tutt's assesment and Greg's arguments. >>>> Please try to understand the issues before assuming things. >>> Perhaps if those boasting of said understanding would invest the energy to >>> take this conversation a bit farther than merely "that won't work", and >>> maybe explore the "but this might..." space a little more deeply and >>> publicly, the ambient level of understanding all 'round would increase, and >>> gosh, we might even see some real progress on this feature. >> Hasn't it all been spelled out yet? We know that (a) lookups are >> expensive, (b) tree walks are expensive, (c) RPCs are expensive. >> Therefore, any design should try to minimize all three. I already posted >> a suggestion about how to speed up lookups by reducing the number of >> tree walks; and if we follow that design and the hint about ACL >> inheritance in NTFS (namely, populate the subutree with explicit values >> or at least single-indirection pointers to explicit values instead of >> calculating the inheritance tree at every lookup), we'll also reduce the >> number of datastore accesses (~~ RPCs ~~ I/O operations), thus reducing >> the cost of /every/ FS implementation. > Hi Brane, > > So it's safe to say that barring a redesign of the backends you > believe that inheritable properties are a non-starter?
I merely agree that true inheritance, as opposed to faked-on-write inheritance, is going to be a problem any way you look at it. And it's not a complete redesign of the backends, "just" the representation of directories, that would improve not only inherited properties but solve quite a few performance (and size) issues, IMO. > This wouldn't > be something I could tempt you to assist with is it? I'm afraid temptation isn't the issue ... lack of time is. Besides, my boss reads this list and it'd look funny if I produced more code here than at $JOB. :-P -- Brane
