hulp nodig bij het optimaliseren van wordpress meta

Ik kwam dit probleem tegen en realiseerde me dat het probleem lag bij alle INNER JOINS die door WordPress werden gegenereerd. Ik kreeg de onbewerkte vraag van WordPress:

SELECT   wp_posts.* FROM wp_posts  
INNER JOIN wp_term_relationships ON (wp_posts.ID = wp_term_relationships.object_id) 
INNER JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id)
INNER JOIN wp_postmeta AS mt1 ON (wp_posts.ID = mt1.post_id)
INNER JOIN wp_postmeta AS mt2 ON (wp_posts.ID = mt2.post_id)
INNER JOIN wp_postmeta AS mt3 ON (wp_posts.ID = mt3.post_id)
INNER JOIN wp_postmeta AS mt4 ON (wp_posts.ID = mt4.post_id)
INNER JOIN wp_postmeta AS mt5 ON (wp_posts.ID = mt5.post_id) WHERE 1=1  AND ( wp_term_relationships.term_taxonomy_id IN (7,11,12,13,14,15) AND wp_posts.ID NOT IN (
                    SELECT object_id
                    FROM wp_term_relationships
                    WHERE term_taxonomy_id IN (10)
                ) ) AND wp_posts.post_type IN ('post', 'page', 'attachment', 'product', 'store_page') AND (wp_posts.post_status = 'publish') AND ( (wp_postmeta.meta_key = 'product_type' AND CAST(wp_postmeta.meta_value AS CHAR) = 'type_pre_ground')
OR  (mt1.meta_key = 'product_type2' AND CAST(mt1.meta_value AS CHAR) = 'type_pre_ground')
OR  (mt2.meta_key = 'product_type3' AND CAST(mt2.meta_value AS CHAR) = 'type_pre_ground')
OR  (mt3.meta_key = 'product_type4' AND CAST(mt3.meta_value AS CHAR) = 'type_pre_ground')
OR  (mt4.meta_key = 'product_type5' AND CAST(mt4.meta_value AS CHAR) = 'type_pre_ground')
OR  (mt5.meta_key = 'product_type6' AND CAST(mt5.meta_value AS CHAR) = 'type_pre_ground') ) GROUP BY wp_posts.ID ORDER BY wp_posts.post_date DESC

Dit is nooit voltooid en legde de CPU vast met een zeer hoge belasting. Ik heb de laatste twee INNER JOIN's (en bijbehorende WHERE-clausules) verwijderd en kreeg binnen 2 seconden resultaten:

SELECT   wp_posts.* FROM wp_posts  
INNER JOIN wp_term_relationships ON (wp_posts.ID = wp_term_relationships.object_id) 
INNER JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id)
INNER JOIN wp_postmeta AS mt1 ON (wp_posts.ID = mt1.post_id)
INNER JOIN wp_postmeta AS mt2 ON (wp_posts.ID = mt2.post_id)
INNER JOIN wp_postmeta AS mt3 ON (wp_posts.ID = mt3.post_id) WHERE 1=1  AND ( wp_term_relationships.term_taxonomy_id IN (7,11,12,13,14,15) AND wp_posts.ID NOT IN (
                    SELECT object_id
                    FROM wp_term_relationships
                    WHERE term_taxonomy_id IN (10)
                ) ) AND wp_posts.post_type IN ('post', 'page', 'attachment', 'product', 'store_page') AND (wp_posts.post_status = 'publish') AND ( (wp_postmeta.meta_key = 'product_type' AND CAST(wp_postmeta.meta_value AS CHAR) = 'type_pre_ground')
OR  (mt1.meta_key = 'product_type2' AND CAST(mt1.meta_value AS CHAR) = 'type_pre_ground')
OR  (mt2.meta_key = 'product_type3' AND CAST(mt2.meta_value AS CHAR) = 'type_pre_ground')
OR  (mt3.meta_key = 'product_type4' AND CAST(mt3.meta_value AS CHAR) = 'type_pre_ground') ) GROUP BY wp_posts.ID ORDER BY wp_posts.post_date DESC

Dus ik realiseerde me dat het verwijderen van de INNER JOINS de sleutel was om de query te versnellen. Ik herschreef de vraag met slechts één wp_postmeta INNER JOIN en kreeg resultaten in fracties van een seconde:

SELECT   wp_posts.* FROM wp_posts  
INNER JOIN wp_term_relationships ON (wp_posts.ID = wp_term_relationships.object_id) 
INNER JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id) WHERE 1=1  AND ( wp_term_relationships.term_taxonomy_id IN (7,11,12,13,14,15) AND wp_posts.ID NOT IN (
                    SELECT object_id
                    FROM wp_term_relationships
                    WHERE term_taxonomy_id IN (10)
                ) ) 
AND wp_posts.post_type IN ('post', 'page', 'attachment', 'product', 'store_page') 
AND (wp_posts.post_status = 'publish') 
AND ( (wp_postmeta.meta_key = 'product_type' AND CAST(wp_postmeta.meta_value AS CHAR) = 'type_pre_ground')
OR  (wp_postmeta.meta_key = 'product_type2' AND CAST(wp_postmeta.meta_value AS CHAR) = 'type_pre_ground')
OR  (wp_postmeta.meta_key = 'product_type3' AND CAST(wp_postmeta.meta_value AS CHAR) = 'type_pre_ground')
OR  (wp_postmeta.meta_key = 'product_type4' AND CAST(wp_postmeta.meta_value AS CHAR) = 'type_pre_ground')
OR  (wp_postmeta.meta_key = 'product_type5' AND CAST(wp_postmeta.meta_value AS CHAR) = 'type_pre_ground')
OR  (wp_postmeta.meta_key = 'product_type6' AND CAST(wp_postmeta.meta_value AS CHAR) = 'type_pre_ground') ) 
GROUP BY wp_posts.ID ORDER BY wp_posts.post_date DESC

Met deze oplossing heb ik een WordPress-filter gemaakt om de postmeta-query naar het snellere formaat te converteren:

function custom_get_meta_sql( $meta_sql )
{
    global $wpdb;

    $posts_table = $wpdb->prefix . 'posts';
    $postmeta_table = $wpdb->prefix . 'postmeta';

    //use single INNER JOIN
    $meta_sql['join'] = " INNER JOIN {$postmeta_table} AS pmta ON ({$posts_table}.ID = pmta.post_id) ";

    //replace the mtNN aliases with wp_postmeta
    $where_clause = $meta_sql['where'];
    $where_clause = str_replace("{$postmeta_table}.", 'pmta.', $where_clause);
    $where_clause = preg_replace('/mt\d+\.meta_/i', 'pmta.meta_', $where_clause);

    $meta_sql['where'] = $where_clause;
    return $meta_sql;
}

add_filter( 'get_meta_sql', 'custom_get_meta_sql' );

Dit filter zou zich in het bestand Functions.php van uw WordPress-thema moeten bevinden.

hulp nodig bij het optimaliseren van wordpress meta_query