Schwartzian transform

Dermot paikkos at
Wed Aug 13 13:45:24 BST 2014

On 13 August 2014 13:24, Abigail <abigail at> wrote:

> On Wed, Aug 13, 2014 at 09:45:59PM +1000, Damian Conway wrote:
> > Mark and Aaron are ntirely correct that the ST is not required for your
> example,
> > but if your actual application uses a significantly larger dataset than
> just
> > four hash entries, then the ST may still be array lookups
> > are around twice as fast as hash lookups. That might be a significant
> > performance enhancement if you have to do O(NlogN) key look-ups for
> > a sufficiently large value of N.
> >
> > As always, only benchmarking on real(istic) data can determine whether
> > you will actually benefit from using the ST or not.
> But if your dataset is that large that you will benefit from halving
> the lookup time, you can save twice the amount of time by not having
> a lookup time at all -- use the Guttman-Rossler Transform.
Does anyone want to venture a guess - highly un-scientific I know but I am,
after all, an instinctive guy - at what the sweet spot for N would be? The
entire data set is about 500,000 records but I doubt that my data structure
would stretch to more than 90 records as these are user created selection.
If N is < 90, I'll opt for ''for'.

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