mysql的慢查詢優化

Question

我有一個購物車，不斷地記錄像這樣的查詢速度慢...

# Query_time: 4 Lock_time: 0 Rows_sent: 50 Rows_examined: 454403 
    SELECT SQL_CALC_FOUND_ROWS products.*, 
          descr1.product       AS product, 
          Min(prices.price)      AS price, 
          GROUP_CONCAT(IF(products_categories.link_type = 'M', 
          Concat(products_categories.category_id, 
          'M'), products_categories.category_id)) AS 
          category_ids, 
          cscart_seo_names.name     AS seo_name 
FROM cscart_products AS products 
     LEFT JOIN cscart_product_descriptions AS descr1 
     ON descr1.product_id = products.product_id 
      AND descr1.lang_code = 'EN' 
     LEFT JOIN cscart_product_prices AS prices 
     ON prices.product_id = products.product_id 
      AND prices.lower_limit = 1 
     INNER JOIN cscart_products_categories AS products_categories 
     ON products_categories.product_id = products.product_id 
     INNER JOIN cscart_categories 
     ON cscart_categories.category_id = products_categories.category_id 
      AND (cscart_categories.usergroup_ids = '' 
        OR Find_in_set(0, cscart_categories.usergroup_ids) 
        OR Find_in_set(1, cscart_categories.usergroup_ids)) 
      AND cscart_categories.status IN ('A', 'H') 
     LEFT JOIN cscart_seo_names 
     ON cscart_seo_names.object_id = products.product_id 
      AND cscart_seo_names.TYPE = 'p' 
      AND cscart_seo_names.dispatch = '' 
      AND cscart_seo_names.lang_code = 'EN' 
WHERE 1 
     AND products.company_id = 0 
     AND (products.usergroup_ids = '' 
       OR Find_in_set(0, products.usergroup_ids) 
       OR Find_in_set(1, products.usergroup_ids)) 
     AND products.status IN ('A') 
     AND prices.usergroup_id IN (0, 0, 1) 
GROUP BY products.product_id 
ORDER BY descr1.product ASC 
LIMIT 1300, 50; 

我似乎無法得到從車公司就如何加快該查詢的任何幫助。也許我需要添加更多索引？我不確定，並希望得到一些幫助，指出我正確解決這個問題的方向。

感謝，

克里斯·愛德華茲

Answer 1

我看到了很多與此查詢可能會造成速度緩慢的問題...

首先，在任何地方使用的是「FIND_IN_SET」，嘗試用IN代替。通過在條件去掉「OR」，索引可以使用：

cscart_categories.usergroup_ids = '' 
OR FIND_IN_SET(0, cscart_categories.usergroup_ids) 
OR FIND_IN_SET(1, cscart_categories.usergroup_ids) 

變爲：

cscart_categories.usergroup_ids IN ('', '0', '1') 

除此之外，確保每一個正在被使用的柱聯接，GROUP BY子句，where子句或排序進行索引。

另一個建議是刪除'GROUP_CONCAT'並在另一個查詢中單獨選擇該信息。