WordPress 在共享主机上优化 Proximity-based 存储位置搜索？

问题描述

我有一个项目，我需要为客户建立一个商店定位器。

我使用自定义的帖子类型 「restaurant-location」，并且我已经编写了代码，以使用 Google Geocoding API(保存 geocodes the US White House in JSON 和我已经将纬度和纬度存储在自定义字段中的链接) 对存储在 postmeta 中的地址进行地理编码。

我已经写了一个 get_posts_by_geo_distance()函数，它返回一个帖子列表，按照这些位置在地理上最接近的位置使用我在这篇文章幻灯片中找到的公式。你可能会这样调用我的函数 (我从一个固定的”source” lat /long 开始)：

include "wp-load.php";

$source_lat = 30.3935337;
$source_long = -86.4957833;

$results = get_posts_by_geo_distance(
    'restaurant-location',
    'geo_latitude',
    'geo_longitude',
    $source_lat,
    $source_long);

echo '<ul>';
foreach($results as $post) {
    $edit_url = get_edit_url($post->ID);
    echo "<li>{$post->distance}: <a href="{$edit_url}" target="_blank">{$post->location}</a></li>";
}
echo '</ul>';
return;

这里是 get_posts_by_geo_distance()本身的功能：

function get_posts_by_geo_distance($post_type,$lat_key,$lng_key,$source_lat,$source_lng) {
    global $wpdb;
    $sql =<<<SQL
SELECT
    rl.ID,
    rl.post_title AS location,
    ROUND(3956*2*ASIN(SQRT(POWER(SIN(({$source_lat}-abs(lat.lat))*pi()/180/2),2)+
    COS({$source_lat}*pi()/180)*COS(abs(lat.lat)*pi()/180)*
    POWER(SIN(({$source_lng}-lng.lng)*pi()/180/2),2))),3) AS distance
FROM
    wp_posts rl
    INNER JOIN (SELECT post_id,CAST(meta_value AS DECIMAL(11,7)) AS lat FROM wp_postmeta lat WHERE lat.meta_key='{$lat_key}') lat ON lat.post_id = rl.ID
    INNER JOIN (SELECT post_id,CAST(meta_value AS DECIMAL(11,7)) AS lng FROM wp_postmeta lng WHERE lng.meta_key='{$lng_key}') lng ON lng.post_id = rl.ID
WHERE
    rl.post_type='{$post_type}' AND rl.post_name<>'auto-draft'
ORDER BY
    distance
SQL;
    $sql = $wpdb->prepare($sql,$source_lat,$source_lat,$source_lng);
    return $wpdb->get_results($sql);
}

我担心的是，SQL 可以像你一样，就像 non-optimized 一样。由于源地理位置是可更改的，并且没有一组有限的源地理数据缓存，所以 MySQL 不能由任何可用的索引进行排序。目前，我很高兴能够优化它。

考虑到我已经做了这个问题是：你将如何优化这个 use-case？

如果一个更好的解决方案会让我抛出来，我保留我做的一切并不重要。除了需要像安装 Sphinx 服务器或需要自定义 MySQL 配置的任何东西之外，我可以考虑几乎任何解决方案。基本上，解决方案需要能够在任何简单的香草 WordPress 安装上工作。 (也就是说，如果有人想为其他可能能够获得更高级和后代的人列出替代解决方案，那将是巨大的。)

找到资源

FYI，我做了一些研究，而不是再次做研究，而不是你发布任何这些链接作为答案，我会继续包括他们。

• http://jebaird.com/blog/calculating-distance-miles-latitude-and-longitude

• http://wordpress.org/extend/plugins/geolocation/screenshots/

• http://code.google.com/apis/maps/articles/phpsqlsearch.html

• http://www.rooftopsolutions.nl/blog/229

• http://planet.mysql.com/entry/?id=18085

• http://blog.peoplesdns.com/archives/24

• http://www.petefreitag.com/item/622.cfm

• http://www.phpro.org/tutorials/Geo-Targetting-With-PHP-And-MySQL.html

• http://forum.geonames.org/gforum/posts/list/692.page

• http://forums.mysql.com/list.php?23

• http://www.scribd.com/doc/2569355/Geo-Distance-Search-with-MySQL

• http://developer.yahoo.com/maps/rest/V1/geocode.html

• http://geocoder.us/

关于狮身人面像搜索

• http://sphinxsearch.com/

• https://launchpad.net/wp-sphinx-plugin

• http://forums.site5.com/showthread.php?t=28981

• http://wordpress.org/extend/plugins/wordpress-sphinx-plugin/

• http://wordpress.org/extend/plugins/sphinx-search/

• http://www.mysqlperformanceblog.com/2008/02/15/mysql-performance-blog-now-uses-sphinx-for-site-search/

最佳解决方案

你需要什么精度？如果它是一个国家/全国范围的搜索，也许你可以做一个 lat-lon 来压缩查找，并预先计算距离从 zip 区域到餐厅的拉链区域。如果您需要准确的距离，那将不是一个好的选择。

你应该研究一个 Geohash 解决方案，在维基百科的文章中有一个链接到一个 PHP 库来编码解码长度到 geohashs 。

在这里，您有一个很好的文章，解释 Google App Engine 中的原因及其使用方法 (Python 代码，但易于遵循) 由于需要在 GAE 中使用 geohash，您可以找到一些很好的 python 库和示例。

正如这篇博客文章解释的那样，使用 geohash 的优点是可以在该字段的 MySQL 表上创建一个索引。

次佳解决方案

这可能对你来说太晚了，但是我也要用 a similar answer as I gave to this related question 来回复，所以未来的访问者可以参考这两个问题。

我不会将这些值存储在帖子元数据表中，或者至少不仅在这里。你想要一个表与 post_id，lat，lon 列，所以你可以放置一个索引的 lat, lon 和查询。这不应该是太难以保持最新的挂钩保存和更新。

查询数据库时，您可以在起始点周围定义一个边界框，因此您可以对该框的 North-South 和 East-West 边框之间的所有 lat, lon 对进行有效的查询。

得到这个减少的结果后，您可以进行更先进的 (圆形或实际的行车路线) 距离计算，以过滤出边界角落中的位置，并进一步远离您的需要。

在这里，您可以找到一个在管理区域工作的简单代码示例。您需要自己创建额外的数据库表。代码是从大多数到最不重要的。

<?php
/*
Plugin Name: Monkeyman geo test
Plugin URI: http://www.monkeyman.be
Description: Geolocation test
Version: 1.0
Author: Jan Fabry
*/

class Monkeyman_Geo
{
    public function __construct()
    {
        add_action('init', array(&$this, 'registerPostType'));
        add_action('save_post', array(&$this, 'saveLatLon'), 10, 2);

        add_action('admin_menu', array(&$this, 'addAdminPages'));
    }

    /**
     * On post save, save the metadata in our special table
     * (post_id INT, lat DECIMAL(10,5), lon DECIMAL (10,5))
     * Index on lat, lon
     */
    public function saveLatLon($post_id, $post)
    {
        if ($post->post_type != 'monkeyman_geo') {
            return;
        }
        $lat = floatval(get_post_meta($post_id, 'lat', true));
        $lon = floatval(get_post_meta($post_id, 'lon', true));

        global $wpdb;
        $result = $wpdb->replace(
            $wpdb->prefix . 'monkeyman_geo',
            array(
                'post_id' => $post_id,
                'lat' => $lat,
                'lon' => $lon,
            ),
            array('%s', '%F', '%F')
        );
    }

    public function addAdminPages()
    {
        add_management_page( 'Quick location generator', 'Quick generator', 'edit_posts', __FILE__  . 'generator', array($this, 'doGeneratorPage'));
        add_management_page( 'Location test', 'Location test', 'edit_posts', __FILE__ . 'test', array($this, 'doTestPage'));

    }

    /**
     * Simple test page with a location and a distance
     */
    public function doTestPage()
    {
        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>Center latitude: <input size="10" name="center_lat" value="{$default_lat}"/>
        <br/>Center longitude: <input size="10" name="center_lon" value="{$default_lon}"/>
        <br/>Max distance (km): <input size="5" name="max_distance" value="100"/></p>
    <p><input type="submit" name="search" value="Search!"/></p>
</form>
EOF;
            return;
        }
        $center_lon = floatval($_REQUEST['center_lon']);
        $center_lat = floatval($_REQUEST['center_lat']);
        $max_distance = floatval($_REQUEST['max_distance']);

        var_dump(self::getPostsUntilDistanceKm($center_lon, $center_lat, $max_distance));
    }

    /**
     * Get all posts that are closer than the given distance to the given location
     */
    public static function getPostsUntilDistanceKm($center_lon, $center_lat, $max_distance)
    {
        list($north_lat, $east_lon, $south_lat, $west_lon) = self::getBoundingBox($center_lat, $center_lon, $max_distance);

        $geo_posts = self::getPostsInBoundingBox($north_lat, $east_lon, $south_lat, $west_lon);

        $close_posts = array();
        foreach ($geo_posts as $geo_post) {
            $post_lat = floatval($geo_post->lat);
            $post_lon = floatval($geo_post->lon);
            $post_distance = self::calculateDistanceKm($center_lat, $center_lon, $post_lat, $post_lon);
            if ($post_distance < $max_distance) {
                $close_posts[$geo_post->post_id] = $post_distance;
            }
        }
        return $close_posts;
    }

    /**
     * Select all posts ids in a given bounding box
     */
    public static function getPostsInBoundingBox($north_lat, $east_lon, $south_lat, $west_lon)
    {
        global $wpdb;
        $sql = $wpdb->prepare('SELECT post_id, lat, lon FROM ' . $wpdb->prefix . 'monkeyman_geo WHERE lat < %F AND lat > %F AND lon < %F AND lon > %F', array($north_lat, $south_lat, $west_lon, $east_lon));
        return $wpdb->get_results($sql, OBJECT_K);
    }

    /* Geographical calculations: distance and bounding box */

    /**
     * Calculate the distance between two coordinates
     * http://stackoverflow.com/questions/365826/calculate-distance-between-2-gps-coordinates/1416950#1416950
     */
    public static function calculateDistanceKm($a_lat, $a_lon, $b_lat, $b_lon)
    {
        $d_lon = deg2rad($b_lon - $a_lon);
        $d_lat = deg2rad($b_lat - $a_lat);
        $a = pow(sin($d_lat/2.0), 2) + cos(deg2rad($a_lat)) * cos(deg2rad($b_lat)) * pow(sin($d_lon/2.0), 2);
        $c = 2 * atan2(sqrt($a), sqrt(1-$a));
        $d = 6367 * $c;

        return $d;
    }

    /**
     * Create a box around a given point that extends a certain distance in each direction
     * http://www.colorado.edu/geography/gcraft/warmup/aquifer/html/distance.html
     *
     * @todo: Mind the gap at 180 degrees!
     */
    public static function getBoundingBox($center_lat, $center_lon, $distance_km)
    {
        $one_lat_deg_in_km = 111.321543; // Fixed
        $one_lon_deg_in_km = cos(deg2rad($center_lat)) * 111.321543; // Depends on latitude

        $north_lat = $center_lat + ($distance_km / $one_lat_deg_in_km);
        $south_lat = $center_lat - ($distance_km / $one_lat_deg_in_km);

        $east_lon = $center_lon - ($distance_km / $one_lon_deg_in_km);
        $west_lon = $center_lon + ($distance_km / $one_lon_deg_in_km);

        return array($north_lat, $east_lon, $south_lat, $west_lon);
    }

    /* Below this it's not interesting anymore */

    /**
     * Generate some test data
     */
    public function doGeneratorPage()
    {
        if (!array_key_exists('generate', $_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}"/>
        <br/>Max distance (km): <input size="5" name="max_distance" value="100"/></p>
    <p><input type="submit" name="generate" value="Generate!"/></p>
</form>
EOF;
            return;
        }
        $post_count = intval($_REQUEST['post_count']);
        $center_lon = floatval($_REQUEST['center_lon']);
        $center_lat = floatval($_REQUEST['center_lat']);
        $max_distance = floatval($_REQUEST['max_distance']);

        list($north_lat, $east_lon, $south_lat, $west_lon) = self::getBoundingBox($center_lat, $center_lon, $max_distance);


        add_action('save_post', array(&$this, 'setPostLatLon'), 5);
        $precision = 100000;
        for ($p = 0; $p < $post_count; $p++) {
            self::$currentRandomLat = mt_rand($south_lat * $precision, $north_lat * $precision) / $precision;
            self::$currentRandomLon = mt_rand($west_lon * $precision, $east_lon * $precision) / $precision;

            $location = sprintf('(%F, %F)', self::$currentRandomLat, self::$currentRandomLon);

            $post_data = array(
                'post_status' => 'publish',
                'post_type' => 'monkeyman_geo',
                'post_content' => 'Point at ' . $location,
                'post_title' => 'Point at ' . $location,
            );

            var_dump(wp_insert_post($post_data));
        }
    }

    public static $currentRandomLat = null;
    public static $currentRandomLon = null;

    /**
     * Because I didn't know how to save meta data with wp_insert_post,
     * I do it here
     */
    public function setPostLatLon($post_id)
    {
        add_post_meta($post_id, 'lat', self::$currentRandomLat);
        add_post_meta($post_id, 'lon', self::$currentRandomLon);
    }

    /**
     * Register a simple post type for us
     */
    public function registerPostType()
    {
        register_post_type(
            'monkeyman_geo',
            array(
                'label' => 'Geo Location',
                'labels' => array(
                    'name' => 'Geo Locations',
                    'singular_name' => 'Geo Location',
                    'add_new' => 'Add new',
                    'add_new_item' => 'Add new location',
                    'edit_item' => 'Edit location',
                    'new_item' => 'New location',
                    'view_item' => 'View location',
                    'search_items' => 'Search locations',
                    'not_found' => 'No locations found',
                    'not_found_in_trash' => 'No locations found in trash',
                    'parent_item_colon' => null,
                ),
                'description' => 'Geographical locations',
                'public' => true,
                'exclude_from_search' => false,
                'publicly_queryable' => true,
                'show_ui' => true,
                'menu_position' => null,
                'menu_icon' => null,
                'capability_type' => 'post',
                'capabilities' => array(),
                'hierarchical' => false,
                'supports' => array(
                    'title',
                    'editor',
                    'custom-fields',
                ),
                'register_meta_box_cb' => null,
                'taxonomies' => array(),
                'permalink_epmask' => EP_PERMALINK,
                'rewrite' => array(
                    'slug' => 'locations',
                ),
                'query_var' => true,
                'can_export' => true,
                'show_in_nav_menus' => true,
            )
        );
    }
}

$monkeyman_Geo_instance = new Monkeyman_Geo();

参考文献

• Optimizing a Proximity-based Store Location Search on a Shared Web Host?

注：本文内容整合自 Google/Baidu/Bing 辅助翻译的英文资料结果。如果您对结果不满意，可以加入我们改善翻译效果：薇晓朵技术论坛。