[Lustre-devel] Doubly indexed tree / changelogs

Peter Braam Peter.Braam at Sun.COM
Tue Sep 23 19:50:51 PDT 2008

The idea is ok, but scale may turn out to be different than expected.

There could be a huge amount of filesets containing the word "Bin Laden",
say 100,000 of them.

Would two directories work?


On 9/23/08 3:38 PM, "Nikita Danilov" <Nikita.Danilov at Sun.COM> wrote:

> Peter Braam writes:
>> Hi Nikita, Nathan -
>> After some pondering I have come to two conclusions.
>> To encode filesets, we need a tree that makes two iterations fast:
>> 1. list all filesets that contain a certain object
>> 2. list all objects in a certain fileset
>> Is there a doubly indexed tree for this?
> I don't know of a data-structure that provides ready solution for this.
> As Alex pointed out k-d-trees do not fit there (they effectively use a
> key composed of the alternating sequences of bits of the original keys),
> and `geographical trees' that data bases use to store 2-d data use very
> special notion of proximity.
> But, thinking about a fileset as a generalized directory, isn't this the
> same problem as `list all files in directory' and `find all parent
> directories of a file'? It probably makes sense to use the same
> mechanism to deal with directories and filesets.
> Our current solution is to use EA to keep track of all parent
> directories, do you see any problems with applying it to filesets?
>> Peter
> Nikita.

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