Prestashop search slow after migrating from MySQL to MariaDB - mysql

Question

After migrating Prestashop instance from MySQL to MariaDB filtered search queries are gotten slow. Here's an example of a such slow query.
SELECT
fl.name feature_name,
fp.id_feature,
fv.id_feature_value,
fvl.value,
COUNT(DISTINCT p.id_product) nbr,
lifl.url_name name_url_name,
lifl.meta_title name_meta_title,
lifvl.url_name value_url_name,
lifvl.meta_title value_meta_title,
psi.price_min,
psi.price_max,
m.name
FROM
ps_feature_product fp
INNER JOIN
ps_product p
ON
(p.id_product = fp.id_product)
LEFT JOIN
ps_feature_lang fl
ON
(
fl.id_feature = fp.id_feature AND fl.id_lang = 2
)
INNER JOIN
ps_feature_value fv
ON
(
fv.id_feature_value = fp.id_feature_value AND(
fv.custom IS NULL OR fv.custom = 0
)
)
LEFT JOIN
ps_feature_value_lang fvl
ON
(
fvl.id_feature_value = fp.id_feature_value AND fvl.id_lang = 2
)
LEFT JOIN
ps_layered_indexable_feature_lang_value lifl
ON
(
lifl.id_feature = fp.id_feature AND lifl.id_lang = 2
)
LEFT JOIN
ps_layered_indexable_feature_value_lang_value lifvl
ON
(
lifvl.id_feature_value = fp.id_feature_value AND lifvl.id_lang = 2
)
INNER JOIN
ps_product_shop product_shop
ON
(
product_shop.id_product = p.id_product AND product_shop.id_shop = 1
)
INNER JOIN
`ps_layered_price_index` psi
ON
(
psi.id_product = p.id_product AND psi.id_currency = 2 AND psi.id_shop = 1
)
LEFT JOIN
`ps_manufacturer` m
ON
(
m.id_manufacturer = p.id_manufacturer
)
WHERE
product_shop.`active` = 1 AND product_shop.`visibility` IN("both", "catalog") AND fp.id_feature = 9 AND p.id_product IN(
SELECT
id_product
FROM
ps_category_product cp
INNER JOIN
ps_category c
ON
(
c.id_category = cp.id_category AND c.id_category = 13 AND c.active = 1
)
) AND p.id_product IN(
SELECT
id_product
FROM
ps_feature_product fp
WHERE
fp.`id_feature_value` = 39
) AND p.id_product IN(
SELECT
id_product
FROM
ps_feature_product fp
WHERE
fp.`id_feature_value` = 18
) AND p.id_product IN(
SELECT
id_product
FROM
ps_feature_product fp
WHERE
fp.`id_feature_value` = 13
) AND p.id_product IN(
SELECT
id_product
FROM
ps_feature_product fp
WHERE
fp.`id_feature_value` = 44
) AND p.id_product IN(
SELECT
id_product
FROM
ps_feature_product fp
WHERE
fp.`id_feature_value` = 3186
)
GROUP BY
fv.id_feature_value
ORDER BY
fv.position
What is interesting is that it gets a lot faster (4s vs 0.4s) if one of the multiple (nearly identical) subqueries in the WHERE clause is removed.
... AND
/*
-- removing any of the six product filters makes
-- the query a lot faster
p.id_product IN(
SELECT
id_product
FROM
ps_feature_product fp
WHERE
fp.`id_feature_value` = 18
)
*/
AND ...
Here's the EXPLAIN output for this query (without the modifications).
Is there's something obvious that needs to be changed somehow? All tables are already OPTIMIZEd with no improvement.

Answer 1

You have several of these:
AND p.id_product IN (
SELECT id_product
FROM ps_feature_product fp
WHERE fp.`id_feature_value` = 39 )
which could be turned into this
AND EXISTS ( SELECT * FROM ps_feature_product
WHERE id_product = p.id_product
AND id_feature_value = 39 )
IN ( SELECT ... ) is poorly optimized.
Be sure to have INDEX(id_product, id_feature_value).
The reason for the difference in performance between MySQL and MariaDB is that several optimization improvements diverged in about 5.6. They involve stuff relating to what you are doing.
Things like
LEFT JOIN ps_layered_indexable_feature_value_lang_value lifvl
ON ( lifvl.id_feature_value = fp.id_feature_value
AND lifvl.id_lang = 2
need a composite INDEX(id_feature_value, id_lang) (in either order). But I can guess from the EXPLAIN that you have such.
Please provide SHOW CREATE TABLE for each table, there may be more advice.
I can't address your specific question because I don't know which line of the EXPLAIN corresponds to the removed clause.