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Mysql query optimization


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One of our customers says that his wesbsite based on prestashop is very slow,

 

Investigating the issue i found  that query below is which it takes more than 2 seconds and it os the slowest one  :

 

SELECT p.id_product, p.ean13, p.reference, p.id_category_default, p.on_sale, p.quantity, p.minimal_quantity, p.price, p.wholesale_price, p.quantity_discount, p.show_price, p.condition, product_shop.on_sale, product_shop.id_category_default, product_shop.minimal_quantity, product_shop.price, product_shop.wholesale_price, product_shop.show_price, product_shop.condition, product_shop.indexed, stock.out_of_stock, IFNULL(stock.quantity, 0) as quantity, MAX(product_attribute_shop.id_product_attribute) id_product_attribute, product_attribute_shop.minimal_quantity AS product_attribute_minimal_quantity, pl.`available_later`, pl.`link_rewrite`, pl.`name`, MAX(image_shop.`id_image`) id_image, DATEDIFF(product_shop.`date_add`, DATE_SUB(NOW(),INTERVAL 20 DAY)) > 0 AS new, product_shop.price AS orderprice FROM  `ps_product` p  INNER JOIN ps_product_shop product_shop ON (product_shop.id_product = p.id_product AND product_shop.id_shop = 1) LEFT JOIN `ps_product_attribute` pa ON (p.`id_product` = pa.`id_product`) LEFT JOIN ps_product_attribute_shop product_attribute_shop ON (product_attribute_shop.id_product_attribute = pa.id_product_attribute AND product_attribute_shop.id_shop = 1 AND product_attribute_shop.`default_on` = 1)  LEFT JOIN ps_stock_available stock ON (stock.id_product = p.id_product AND stock.id_product_attribute = IFNULL(`product_attribute_shop`.id_product_attribute, 0) AND stock.id_shop = 1  AND stock.id_shop_group = 0  ) LEFT JOIN `ps_product_lang` pl ON (p.`id_product` = pl.`id_product` AND pl.`id_lang` = 2 AND pl.id_shop = 1 ) LEFT JOIN `ps_image` i ON (i.`id_product` = p.`id_product`) LEFT JOIN ps_image_shop image_shop ON (image_shop.id_image = i.id_image AND image_shop.id_shop = 1 AND image_shop.cover=1) WHERE product_shop.`id_shop` = 1  AND product_shop.`active` = 1 AND product_shop.`visibility` IN ("both", "catalog") AND p.`id_product` IN ( SELECT cp.`id_product` FROM `ps_category_product` cp WHERE cp.id_category IN (274, 275, 276, 318, 277, 278, 300, 301, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 292, 295, 209)) GROUP BY product_shop.id_product ORDER BY p.`date_add` DESC Limit 0, 6;

 

I rewitre it by removing the IN ( SELECT ......)  put at the end.

 

( SELECT cp.`id_product` FROM `ps_category_product` cp WHERE cp.id_category IN (274, 275, 276, 318, 277, 278, 300, 301, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 292, 295, 209)

 

and replace it whith a join between ps_category_product and ps_product tables as follows :

 

SELECT p.id_product, p.ean13, p.reference, p.id_category_default, p.on_sale, p.quantity, p.minimal_quantity, p.price, p.wholesale_price, p.quantity_discount, p.show_price, p.condition, product_shop.on_sale, product_shop.id_category_default, product_shop.minimal_quantity, product_shop.price, product_shop.wholesale_price, product_shop.show_price, product_shop.condition, product_shop.indexed, stock.out_of_stock, IFNULL(stock.quantity, 0) as quantity, MAX(product_attribute_shop.id_product_attribute) id_product_attribute, product_attribute_shop.minimal_quantity AS product_attribute_minimal_quantity, pl.`available_later`, pl.`link_rewrite`, pl.`name`, MAX(image_shop.`id_image`) id_image, DATEDIFF(product_shop.`date_add`, DATE_SUB(NOW(),INTERVAL 20 DAY)) > 0 AS new, product_shop.price AS orderprice FROM  `ps_product` p  INNER JOIN ps_product_shop product_shop ON (product_shop.id_product = p.id_product AND product_shop.id_shop = 1) LEFT JOIN `ps_product_attribute` pa ON (p.`id_product` = pa.`id_product`) LEFT JOIN ps_product_attribute_shop product_attribute_shop ON (product_attribute_shop.id_product_attribute = pa.id_product_attribute AND product_attribute_shop.id_shop = 1 AND product_attribute_shop.`default_on` = 1)  LEFT JOIN ps_stock_available stock ON (stock.id_product = p.id_product AND stock.id_product_attribute = IFNULL(`product_attribute_shop`.id_product_attribute, 0) AND stock.id_shop = 1  AND stock.id_shop_group = 0  ) LEFT JOIN `ps_product_lang` pl ON (p.`id_product` = pl.`id_product` AND pl.`id_lang` = 2 AND pl.id_shop = 1 ) LEFT JOIN `ps_image` i ON (i.`id_product` = p.`id_product`) LEFT JOIN ps_image_shop image_shop ON (image_shop.id_image = i.id_image AND image_shop.id_shop = 1 AND image_shop.cover=1) join `ps_category_product` cp on p.`id_product`=cp.`id_product` WHERE product_shop.`id_shop` = 1  AND product_shop.`active` = 1 AND product_shop.`visibility` IN ("both", "catalog") and  cp.id_category IN (274, 275, 276, 318, 277, 278, 300, 301, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 292, 295, 209) GROUP BY product_shop.id_product ORDER BY p.`date_add` DESC Limit 0, 6;

 

 

This version is exeuted in 0.01 sec.

 

Is it possibile to rewrite the query in the future version as porposed  ?

 

Thanks.

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No Idea about the module where the query  resides.

The problem arises when we migrated mysql from 5.5 to 5.6 versions.

The same quwry run very fast on 5.5 version ( 0.03 sec) , but on 5.6 it takes 4 seconds and sometimes 8 seconds.

Mysql changed  how to choice of the executio plan of the same query.

 

I solved the issue by adding a new index on ps_product_shop table on id_product field.

 

Now the table structure is :

 

CREATE TABLE `ps_product_shop` (
  `id_product` int(10) unsigned NOT NULL,
  `id_shop` int(10) unsigned NOT NULL,
  `id_category_default` int(10) unsigned DEFAULT NULL,
  `id_tax_rules_group` int(11) unsigned NOT NULL,
  `on_sale` tinyint(1) unsigned NOT NULL DEFAULT '0',
  `online_only` tinyint(1) unsigned NOT NULL DEFAULT '0',
  `ecotax` decimal(17,6) NOT NULL DEFAULT '0.000000',
  `minimal_quantity` int(10) unsigned NOT NULL DEFAULT '1',
  `price` decimal(20,6) NOT NULL DEFAULT '0.000000',
  `wholesale_price` decimal(20,6) NOT NULL DEFAULT '0.000000',
  `unity` varchar(255) DEFAULT NULL,
  `unit_price_ratio` decimal(20,6) NOT NULL DEFAULT '0.000000',
  `additional_shipping_cost` decimal(20,2) NOT NULL DEFAULT '0.00',
  `customizable` tinyint(2) NOT NULL DEFAULT '0',
  `uploadable_files` tinyint(4) NOT NULL DEFAULT '0',
  `text_fields` tinyint(4) NOT NULL DEFAULT '0',
  `active` tinyint(1) unsigned NOT NULL DEFAULT '0',
  `redirect_type` enum('','404','301','302') NOT NULL DEFAULT '',
  `id_product_redirected` int(10) unsigned NOT NULL DEFAULT '0',
  `available_for_order` tinyint(1) NOT NULL DEFAULT '1',
  `available_date` date NOT NULL DEFAULT '0000-00-00',
  `condition` enum('new','used','refurbished') NOT NULL DEFAULT 'new',
  `show_price` tinyint(1) NOT NULL DEFAULT '1',
  `indexed` tinyint(1) NOT NULL DEFAULT '0',
  `visibility` enum('both','catalog','search','none') NOT NULL DEFAULT 'both',
  `cache_default_attribute` int(10) unsigned DEFAULT NULL,
  `advanced_stock_management` tinyint(1) NOT NULL DEFAULT '0',
  `date_add` datetime NOT NULL,
  `date_upd` datetime NOT NULL,
  `pack_stock_type` int(11) unsigned DEFAULT '3',
  `mpr_pp_import_line` int(11) DEFAULT NULL,
  PRIMARY KEY (`id_product`,`id_shop`),
  KEY `id_category_default` (`id_category_default`),
  KEY `date_add` (`date_add`,`active`,`visibility`),
  KEY `indexed` (`indexed`,`active`,`id_product`),
  KEY `idx1` (`id_product`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

 

The added index is idx1. It seems to be a "duplicate" of the PRIMARY KEY as this one has the most left field on id_product. 

But it works. And now. alos on 5.6 version, the query is very fast.

 

STofa

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