[postgis-devel] Calling Index Genii

[Paul Ramsey]

You edit the postgis/gserialized.h file and define or undef GSERIALIZED_ON

BTW, I have a theory now which I just need to test... the data are 3D!
And in fact the new GiST index will build an index WITH DIMENSIONALITY
DETERMINED BY THE DATA. Not by the opclass. So the tree built with the
new index is going to be more expensive to search in 2D than an actual
2D tree would have been. I just need to change my input data to 2D and
see if the performances fall into line to confirm my guess.

P.

On Thu, Dec 30, 2010 at 12:50 AM, Andrea Peri <aperi2007 at gmail.com> wrote:
>
>>On my lap top the loading and index building take about the same
>>amount of time, but the query runs in about 1ms for the old index and
>>about 5ms for the new one. My assumption (thus unconfirmed) is that
>
>>the problem is not in the consistent checks (doing things like
>>reducing the size of the slice detoasted to the minimum necessary for
>>2d queries only improved the times by about 10%) but rather in the
>
>>tree itself: that the new index is just building a crappier tree, so
>>the query has to traverse more of it to get the same answer.
>
> There even an increase of memory resource needed ?
>
> To test this version there is a new key setting to apply in the .configure,
>
> or need to change manually the definitions ?
>
> --
> -----------------
> Andrea Peri
> . . . . . . . . .
> qwerty àèìòù
> -----------------
>
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