我使用此代碼上崗的WordPress:LEFT JOIN PHP的MySQL很慢
$select = SELECT COUNT(DISTINCT wpPost.ID)
FROM `wp_posts` wpPost
RIGHT JOIN `wp_woocommerce_order_itemmeta` wpOrderItem
ON wpOrderItem.`meta_value`='6246'
WHERE wpPost.`post_status`='wc-completed'
GROUP BY wpPost.`ID`
ORDER BY wpPost.`post_date` DESC
$wpdb->get_results("$select");
echo $wpdb->num_rows;
的SELECT COUNT但這個代碼是非常緩慢的,很長一段時間約40秒!
wp_woocommerce_order_itemmeta
有388116條記錄
我刪除不同,但不影響 – Mohammad
檢查索引,應用索引按條件,它將幫助 –
ID和meta_value索引 – Mohammad