我将通过使用数据库索引并最小化实际距离计算的数量来修改gabrielk和链接的博客文章的答案。
如果您知道用户的坐标，并且知道最大距离（例如10公里），则可以绘制一个边界框，该框为20公里乘20公里，当前位置在中间。获取这些边界坐标，仅查询这些经度和纬度之间的存储。请勿在数据库查询中使用三角函数，因为这将阻止使用索引。（因此，如果商店位于边界框的东北角，则您可能离您12公里，但是我们下一步将其丢弃。）
仅计算要退回的几家商店的距离（根据鸟类的飞行情况或实际驾驶方向，如果您愿意）。如果您拥有大量商店，这将大大缩短处理时间。
对于相关的查找（“给最近的十家商店”），您可以执行类似的查找，但是要进行初始距离猜测（因此，您以10公里乘10公里的区域开始，如果没有足够的商店，则将其扩展为20公里乘20公里，依此类推）。对于这个初始距离，您可以一次计算出整个区域内的商店数量并使用它。或记录所需的查询数量并随时间调整。
我在Mike的相关问题处添加了完整的代码示例，这是一个扩展，可为您提供最接近的X位置（快速且未经测试）：
class Monkeyman_Geo_ClosestX extends Monkeyman_Geo
{
public static $closestXStartDistanceKm = 10;
public static $closestXMaxDistanceKm = 1000; // Don't search beyond this
public function addAdminPages()
{
parent::addAdminPages();
add_management_page( 'Location closest test', 'Location closest test', 'edit_posts', __FILE__ . 'closesttest', array(&$this, 'doClosestTestPage'));
}
public function doClosestTestPage()
{
if (!array_key_exists('search', $_REQUEST)) {
$default_lat = ini_get('date.default_latitude');
$default_lon = ini_get('date.default_longitude');
echo <<<EOF
<form action="" method="post">
<p>Number of posts: <input size="5" name="post_count" value="10"/></p>
<p>Center latitude: <input size="10" name="center_lat" value="{$default_lat}"/>
<br/>Center longitude: <input size="10" name="center_lon" value="{$default_lon}"/></p>
<p><input type="submit" name="search" value="Search!"/></p>
</form>
EOF;
return;
}
$post_count = intval($_REQUEST['post_count']);
$center_lon = floatval($_REQUEST['center_lon']);
$center_lat = floatval($_REQUEST['center_lat']);
var_dump(self::getClosestXPosts($center_lon, $center_lat, $post_count));
}
/**
* Get the closest X posts to a given location
*
* This might return more than X results, and never more than
* self::$closestXMaxDistanceKm away (to prevent endless searching)
* The results are sorted by distance
*
* The algorithm starts with all locations no further than
* self::$closestXStartDistanceKm, and then grows this area
* (by doubling the distance) until enough matches are found.
*
* The number of expensive calculations should be minimized.
*/
public static function getClosestXPosts($center_lon, $center_lat, $post_count)
{
$search_distance = self::$closestXStartDistanceKm;
$close_posts = array();
while (count($close_posts) < $post_count && $search_distance < self::$closestXMaxDistanceKm) {
list($north_lat, $east_lon, $south_lat, $west_lon) = self::getBoundingBox($center_lat, $center_lon, $search_distance);
$geo_posts = self::getPostsInBoundingBox($north_lat, $east_lon, $south_lat, $west_lon);
foreach ($geo_posts as $geo_post) {
if (array_key_exists($geo_post->post_id, $close_posts)) {
continue;
}
$post_lat = floatval($geo_post->lat);
$post_lon = floatval($geo_post->lon);
$post_distance = self::calculateDistanceKm($center_lat, $center_lon, $post_lat, $post_lon);
if ($post_distance < $search_distance) {
// Only include those that are in the the circle radius, not bounding box, otherwise we might miss some closer in the next step
$close_posts[$geo_post->post_id] = $post_distance;
}
}
$search_distance *= 2;
}
asort($close_posts);
return $close_posts;
}
}
$monkeyman_Geo_ClosestX_instace = new Monkeyman_Geo_ClosestX();