php - mySQL 查询似乎使服务器崩溃

Question

我有一个 mySQL 查询来处理 WordPress 中相当复杂的搜索，因为我一直在努力让 wp_query 做我需要它做的一切。

但是，有时查询需要很长时间才能运行(有时超过 10 秒!)，有时它似乎只是使服务器(media temple Grid)崩溃，返回一个内部服务器错误或一个建立数据库连接时出错。

我不确定查询中是否存在导致其崩溃的一般语法错误，但本质上生成查询的 PHP 如下所示:

<?php

// declare wordpress database global
global $wpdb;

// order by option
$order = $_SESSION['search']['sort-by'];

// users lat, long and distance preferences
$lat = $_SESSION['search']['lat'];
$long = $_SESSION['search']['long'];
$radius = $_SESSION['search']['distance'];

// user search start/end date
$startDate = date('Ymd', strtotime($_SESSION['search']['from']));
$endDate = date('Ymd', strtotime($_SESSION['search']['to']));

// get the main category search ID
$maincat = get_term_by( 'slug', $_SESSION['search']['cat'], 'main-cat');
$maincat = $maincat->term_taxonomy_id;

// grab keywords, replace special chars and spaces
$keywords = $_SESSION['search']['keyword'];
$keywords = preg_replace('/[^A-Za-z0-9 ,]/u','', strip_tags($keywords));
$keywords = str_replace(' ', '', $keywords);

// put keywords into array
$subcatItems = explode(',', $keywords);
$keywords = $subcatItems;

// for each keywords get the sub category id's
$subcats = array();
$count = count($subcatItems) - 2;
for ($i = 0; $i <= $count; $i++) {
    $subcatItems[$i] = get_term_by( 'slug', $subcatItems[$i], 'sub-cat');
    if ($subcatItems[$i] != '') : 
        $subcatItems[$i] = $subcatItems[$i]->term_taxonomy_id;
        array_push($subcats, $subcatItems[$i]);
    endif;
}
if( $subcats != '' ) :
    $subcats = implode(',', $subcats);
endif;



// select
$query = 'SELECT SQL_CALC_FOUND_ROWS wp_posts.*, ';


// geo locate
$query .= '( 3959 * acos(
     cos( radians('.$lat.') ) 
     * cos( radians( lat ) ) 
     * cos( radians( lng ) - radians('.$long.') ) 
     + sin( radians('.$lat.') ) 
     * sin( radians( lat ) ) 
     ) ) 
 AS distance , lat AS  latitude , lng AS longitude ';


 // from
 $query .= 'FROM wp_posts ';


 // inner joins
 $query .= 'INNER JOIN wp_term_relationships ON (wp_posts.ID = wp_term_relationships.object_id) ';
 if ( $keywords != '' ) :
    $query .= 'INNER JOIN wp_term_relationships AS tt1 ON (wp_posts.ID = tt1.object_id) ';
 endif;
 $query .= 'INNER JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id) ';
 $query .= 'INNER JOIN wp_postmeta AS mt1 ON (wp_posts.ID = mt1.post_id) ';

 // if ordered by price, join post meta again
 if( $order == 'mt2.meta_value+0' ) :
     $query .= 'INNER JOIN wp_postmeta AS mt2 ON (wp_posts.ID = mt2.post_id) ';
 endif;

 // if there are keywords 
 if ( $keywords != '' ) :
    $query .= 'INNER JOIN wp_postmeta AS mt3 ON (wp_posts.ID = mt3.post_id) ';
 endif;

 // join table to geo locate
 $query .= 'INNER JOIN lat_lng_post ON wp_posts.ID = lat_lng_post.post_id ';


 // basic filter
 $query .= 'WHERE 1=1 ';
 $query .= 'AND wp_posts.post_type = "event" '; 
 $query .= 'AND wp_posts.post_status = "publish" ';


 // geo filter
 $query .= 'AND lat_lng_post.lat = lat ';
 $query .= 'AND lat_lng_post.lng = lng ';


 // date filter
 $query .= 'AND ( '; 
 $query .= '(wp_postmeta.meta_key LIKE "date_%_start-date" AND CAST(wp_postmeta.meta_value AS SIGNED) <= "'.$endDate.'") ';
 $query .= 'AND (mt1.meta_key LIKE "date_%_end-date" AND CAST(mt1.meta_value AS SIGNED) >= "'.$startDate.'") ';
 $query .= 'AND substr(wp_postmeta.meta_key, 1, 6) = substr(mt1.meta_key, 1, 6)  ';
 $query .= ') ';


 // taxonomies filter
 $query .= 'AND ( wp_term_relationships.term_taxonomy_id IN ('.$maincat.') ) ';

 // if keywords
 if ( $_SESSION['search']['keyword'] != '' ) :
    $query .= 'AND ( ';

    // for each keyword, and a statement to check post title
    $keywordCount = 0;
    foreach ( $keywords as $keyword ) :
        if( $keyword != '' ) :
            if( $keywordCount == 0 ) :
                $query .= '(wp_posts.post_title LIKE "%'.$keyword.'%") ';
            else :
                $query .= 'OR (wp_posts.post_title LIKE "%'.$keyword.'%") ';
            endif;
        endif;
        $keywordCount++;
    endforeach;

    // for each keyword, and a statement to check description
    foreach ( $keywords as $keyword ) :
        if( $keyword != '' ) :
            $query .= 'OR (mt3.meta_key = "description" AND mt3.meta_value LIKE "%'.$keyword.'%") ';
        endif;
    endforeach;

    // for each keyword, and a statement to check sub category taxonomy
    if( $subcats != '' ) :
        $query .= 'OR ( tt1.term_taxonomy_id IN ('.$subcats.') )';
    endif;

    $query .= ') ';
 endif;     


 // if ordered by adult
 if( $order == 'mt2.meta_value+0' ) :
     $query .= 'AND mt2.meta_key = "adult" ';
 endif;

 // grouping and sorting
 $query .= 'GROUP BY wp_posts.ID ';
 $query .= 'HAVING distance <= '.$radius.' ';
 $query .= 'ORDER BY '.$order.' ASC ';
 $query .= 'LIMIT 0, 10';

 $events = $wpdb->get_results( $query, 'OBJECT' ); 

?>

如果有人有任何想法，请告诉我!如果您需要更多信息，我很乐意提供 :)

编辑

当搜索中有关键字时，查询似乎更加困难。我不确定是否有更好的方法来编写逻辑:

if ( $_SESSION['search']['keyword'] != '' ) :
    $query .= 'AND ( ';

    // for each keyword, and a statement to check post title
    $keywordCount = 0;
    foreach ( $keywords as $keyword ) :
        if( $keyword != '' ) :
            if( $keywordCount == 0 ) :
                $query .= '(wp_posts.post_title LIKE "%'.$keyword.'%") ';
            else :
                $query .= 'OR (wp_posts.post_title LIKE "%'.$keyword.'%") ';
            endif;
        endif;
        $keywordCount++;
    endforeach;

    // for each keyword, and a statement to check description
    foreach ( $keywords as $keyword ) :
        if( $keyword != '' ) :
            $query .= 'OR (mt3.meta_key = "description" AND mt3.meta_value LIKE "%'.$keyword.'%") ';
        endif;
    endforeach;

    // for each keyword, and a statement to check sub category taxonomy
    if( $subcats != '' ) :
        $query .= 'OR ( tt1.term_taxonomy_id IN ('.$subcats.') )';
    endif;

    $query .= ') ';
 endif;

编辑 2

我刚才的另一个想法是，将查询拆分成单独的查询会不会更快？所以先完成地理查询，获取那些帖子 ID 并进行日期查询，然后再进行关键字查询？我对 mySQL 很陌生，所以不太确定如何优化它:/

Answer 1

尝试将最终条件添加到连接(多个连接条件)。

如果您在连接时使用多个条件而不是获得一个巨大的集合，然后将条件放在末尾，您的集合会更小，响应时间可能会更好。

例如，你有一个最终条件:

AND wp_posts.post_type = "event"

你可以把它放在第一个连接中

INNER JOIN wp_term_relationships ON (wp_posts.ID = wp_term_relationships.object_id) AND wp_posts.post_type = "event"
INNER JOIN...

等等。