[OSM-dev] More about spatial indexes
andreaskalsch at gmx.de
Mon Sep 29 19:33:39 BST 2008
Marcus Wolschon schrieb:
> Andreas Kalsch schrieb:
>> ... are nearly 4 times faster than multi.colum indices for lat/lon
>> in MySQL. Extracting 1 column / 17.000 rows out of 1 million takes
>> .39 secs vs. 1.39 - I think all Postgres guys know a similar value.
>> I think this is a pretty impressing result.
> Does the spatial extension come pre-installed with mysql?
> = can I expect it to be present for a home-user with no
> knowledge of software that has a mysql running?
It is preinstalled even in MySQL 4. It implements the OpenGIS standard
for MyISAM tables without some rarely used features.
You have to use the special types "Point", "LinearString" ..., a spatial
index ( "alter table x add spatial index(column)" ) and some functions
to make operations upon the data - e.g. the prominent example whether
points are inside a bounding box. This is for what R-Trees are implemented.
To take a deeper look inside the online doc is a good idea. There are
some very useful tips about SQL optimization and: Learn to use the
console if you have not done yet. Most MySQL admin tools don't support
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