Posted by Iván Sánchez Ortega on 01/05/07 03:19

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Jerry Stuckle wrote:

> Now use the spacial extensions in MySQL, but also filter on the
> longitude and latitude values you computed (in your WHERE clause), i.e.
>
> WHERE long >= elong AND long <= wlong AND lat >= nlat AND lat <= slat

No, you shouldn't do that. If you're using spatial extensions, then define a
bounding box (with GeomFromText('POLYGON blahblahblah') ), then use a
spatial MBR intersection function to filter the data.

The result will be the same (filtering the points by a rectangle centered on
a point). However, by *only* using spatial functions, the Q-trees
algorithms can kick in, and filter the data faster than using four
non-spatial comparisons. After all, that's why Q-trees and spatial stuff
was invented.

- --
- ----------------------------------
Iván Sánchez Ortega -ivansanchez-algarroba-escomposlinux-punto-org-

Well, if you're not running Windows, how the hell else are you supposed to
get memory leaks? They don't just grow on B-Trees, y'know!
-- Tackhead, on Slashdot.
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