Yes, spatial indexes are very fast:
Query would be something like:
SET @center = GeomFromText('POINT(37.372241 -122.021671)');
SET @radius = 0.005;
SET @bbox = GeomFromText(CONCAT('POLYGON((',
X(@center) - @radius, ' ', Y(@center) - @radius, ',',
X(@center) + @radius, ' ', Y(@center) - @radius, ',',
X(@center) + @radius, ' ', Y(@center) + @radius, ',',
X(@center) - @radius, ' ', Y(@center) + @radius, ',',
X(@center) - @radius, ' ', Y(@center) - @radius, '))')
);
select id, astext(coordinates), Distance(@center,line_segment) as dist
FROM places where MBRContains(@bbox, line_segment) order by dist limit 10;
Regards,
Gavin Towey
-----Original Message-----
From: René Fournier [mailto:m...@renefournier.com]
Sent: Wednesday, December 16, 2009 4:32 PM
To: mysql
Subject: Spatial extensions
I have table with 2 million rows of geographic points (latitude, longitude).
Given a location -- say, 52º, -113.9º -- what's the fastest way to query the 10
closest points (records) from that table? Currently, I'm using a simple
two-column index to speed up queries:
CREATE TABLE `places` (
`id` mediumint(8) unsigned NOT NULL AUTO_INCREMENT,
`latitude` decimal(10,8) NOT NULL,
`longitude` decimal(12,8) NOT NULL
PRIMARY KEY (`id`),
KEY `latlng` (`latitude`,`longitude`)
) ENGINE=MyISAM AUTO_INCREMENT=50 DEFAULT CHARSET=latin1
COLLATE=latin1_general_ci;
My current query is fairly quick:
SELECT SQL_NO_CACHE * FROM places WHERE latitude BETWEEN 51.98228037384 AND
52.033153677 AND longitude BETWEEN -113.94770681881 AND -113.86685484296;
But I wonder a couple things:
1. Would MySQL's [seemingly anemic] spatial extensions would speed things up if
I added a column of type POINT (and a corresponding spatial INDEX)?
CREATE TABLE `places` (
`id` mediumint(8) unsigned NOT NULL AUTO_INCREMENT,
`latitude` decimal(10,8) NOT NULL,
`longitude` decimal(12,8) NOT NULL,
`coordinates` point NOT NULL,
PRIMARY KEY (`id`),
KEY `latlng` (`latitude`,`longitude`),
KEY `coord` (`coordinates`(25))
) ENGINE=MyISAM AUTO_INCREMENT=50 DEFAULT CHARSET=latin1
COLLATE=latin1_general_ci;
2. How would I write the query?
...Rene
--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql?unsub=gto...@ffn.com
This message contains confidential information and is intended only for the
individual named. If you are not the named addressee, you are notified that
reviewing, disseminating, disclosing, copying or distributing this e-mail is
strictly prohibited. Please notify the sender immediately by e-mail if you
have received this e-mail by mistake and delete this e-mail from your system.
E-mail transmission cannot be guaranteed to be secure or error-free as
information could be intercepted, corrupted, lost, destroyed, arrive late or
incomplete, or contain viruses. The sender therefore does not accept liability
for any loss or damage caused by viruses or errors or omissions in the contents
of this message, which arise as a result of e-mail transmission. [FriendFinder
Networks, Inc., 220 Humbolt court, Sunnyvale, CA 94089, USA, FriendFinder.com
--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
