After updating the database (MySQL 5.7) on the sites working on Magento 1.9, there were queries that were very slow. All slow requests began:
SELECT `e`.*, `core_url_rewrite`.`request_path`, IF(at_is_active.value_id > 0, at_is_active.value, at_is_active_default.value) AS `is_active` FROM `catalog_category_entity` AS `e`
The full text of the request will be below.
The problem arose because MySQL stopped using indexes.
Continue reading Magento + MySQL 5.7 = Slow Queries