I really don't know if this would change something, but... Would the
performance be improved if you read/write a file which is stored on a RAM
filesystem? (like tmpfs, http://en.wikipedia.org/wiki/Tmpfs)
I imagine that anyway the data should be moved from the tmpfs to the RAM
where the program effectively operate, but you would have to r/w from ram
instead of disk.



2011/3/24 brunetto <brunetto.zi...@gmail.com>

> 2011/3/23 Francesc Alted <fal...@pytables.org>:
> > 2011/3/23 brunetto <brunetto.zi...@gmail.com>
> >>
> >> For now the leaves max size is 300 (that is: leaves are Arrays
> >> containing 300 or less integers), the number of nodes dipends on the
> >> dimension of the dataset. Now I'm using dataset between 1000 and 10^8
> >> elements. The tree is built splitting every node (=PyTables Group) in
> >> two children until the number of elements is <=300.
> >
> > I see.  May I ask why you use the 300 magic figure?  >From a PyTables
> > performance point of view, perhaps it might make more sense to have
> larger
> > Arrays and lesser nodes.
>
> Because my tree comes from a previus in-memory implementation... At
> that time I did some tests and I found that on average the max speed
> correspond to leaves of <= 300 elements.
>
> I think this is because of what I do when I open a leaf, i.e.
> calculate distances and sorting arrays. Bigger leaves lead to longer
> operation on them!
>
> Also I can't use the walkNode method because I have a selective
> travers that automatically exclude all the nodes (and their subnodes)
> that are more distant than a certain quantity (spatially distant...
> every node has spatial coordinates).
>
> brunetto
>
>
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