I just did a quick look at the documentation on the mysql spatial
extension and it seems like over kill for what you are looking for. An
easy way to approximate the search for all points a given distance from
another is to simply use a bounding box. An index on the X and Y
coordinates of the point then will make the search fast. something like
this...
SELECT *
FROM points
WHERE x >= minx AND x <= maxx AND y >= miny AND y <= maxy
If your data is evenly distributed in the space about 21% of the
returned points will be outside the distance you want. You can then use
a script to scan the result to find and reject the points you don't
want. I do this for a mapping project I have on a web site. I don't
have a lot of data so I can't say how well the performance is. Even if
you have a huge data set, as long as your result sets weren't too big,
this should be pretty fast.
If the points you are dealing with are latitude longitude coordinates, I
have the formula you need to calculate the distance written in PHP if
you want it.
Rob Wultsch wrote:
I have been storing points in mysql without use of the spatial
extension. I do not forsee the need to ever store more than points,
and am wondering if the spatial extensions would offer any significant
advantages. I have looked a bit for tutorials, etc... and have not
found much.
One feature that I would like is to be able to find all points withen
X distance from of point Y, without doing a table scan. Would the
spatial index (Rtree) be able to achieve this?
Are there any good tutorials (or heaven forbid, books) that anyone can suggest?
Should I go hang out with the cool kids that are using postGIS ;)
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