1
У меня есть таблица отношений, как показано ниже:SQL - запрос работает очень медленно
бегаю следующий запрос из PHP и побежал в двух больших проблем.
1) Максимальный предел памяти превысил
2) Максимальное время выполнения превысило
SELECT DISTINCT venues.name, locations.location, events.event, types.type, foods.food, beverages.beverage, event_options.event_option, styles.style, space_requirements.space_requirement, features.feature
FROM (SELECT * FROM venues v LIMIT $offset,$limit) venues
INNER JOIN locations ON venues.location_id = locations.location_id
LEFT JOIN venue_events ON venues.venue_id = venue_events.venue_id
LEFT JOIN events ON events.event_id = venue_events.event_id
LEFT JOIN venue_types ON venues.venue_id = venue_types.venue_id
LEFT JOIN types ON types.type_id = venue_types.type_id
LEFT JOIN venue_foods ON venues.venue_id = venue_foods.venue_id
LEFT JOIN foods ON foods.food_id = venue_foods.food_id
LEFT JOIN venue_beverages ON venues.venue_id = venue_beverages.venue_id
LEFT JOIN beverages ON beverages.beverage_id = venue_beverages.beverage_id
LEFT JOIN venue_event_options ON venues.venue_id = venue_event_options.venue_id
LEFT JOIN event_options ON event_options.event_option_id = venue_event_options.event_option_id
LEFT JOIN venue_styles ON venues.venue_id = venue_styles.venue_id
LEFT JOIN styles ON styles.style_id = venue_styles.style_id
LEFT JOIN venue_space_requirements ON venues.venue_id = venue_space_requirements.venue_id
LEFT JOIN space_requirements ON space_requirements.space_requirement_id = venue_space_requirements.space_requirement_id
LEFT JOIN venue_features ON venues.venue_id = venue_features.venue_id
LEFT JOIN features ON features.feature_id = venue_features.feature_id
Я использую этот запрос, чтобы получить все аксессуары, связанные с каждым местом. Мне нужно реализовать разбиение на страницы в бэкэнд, поэтому я использую LIMIT $ offset, $ limit в Sub Query. Я не мог найти никакой другой идеи (запроса), чтобы получить тот же результат, который я сейчас получаю. В настоящее время я использую
ini_set('memory_limit', '-1');
ini_set('max_execution_time', 60);
PHP функции, чтобы игнорировать эти проблемы, но я думаю, что это не лучшая практика. Также я думаю о том условии, когда мне, возможно, придется достать все принадлежности 50+ мест, для которых max_execution_time = 60 может быть недостаточно.
Как я могу избавиться от этой проблемы? Пожалуйста, помогите мне.
Обновленный
Числа строк извлекаемый (события * тип * еда * напитки * event_options * стили * space_requirements * особенность) каждое место есть. Но количество полезных для меня строк - это не умножение, а сумма.
И вот результат я нашел после того, как работает мой запрос с ключевым словом EXPLAIN
Array
(
[0] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] =>
[type] => ALL
[possible_keys] =>
[key] =>
[key_len] =>
[ref] =>
[rows] => 11
[Extra] => Using temporary
)
[1] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => venue_events
[type] => ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 4
[ref] => venues.venue_id
[rows] => 3
[Extra] => Using index
)
[2] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => events
[type] => eq_ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 1
[ref] => serofero_mvb.venue_events.event_id
[rows] => 1
[Extra] =>
)
[3] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => venue_types
[type] => ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 4
[ref] => venues.venue_id
[rows] => 7
[Extra] => Using index
)
[4] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => types
[type] => eq_ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 1
[ref] => serofero_mvb.venue_types.type_id
[rows] => 1
[Extra] =>
)
[5] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => venue_foods
[type] => ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 4
[ref] => venues.venue_id
[rows] => 3
[Extra] => Using index
)
[6] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => foods
[type] => eq_ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 1
[ref] => serofero_mvb.venue_foods.food_id
[rows] => 1
[Extra] => Using index
)
[7] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => venue_beverages
[type] => ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 4
[ref] => venues.venue_id
[rows] => 3
[Extra] => Using index
)
[8] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => beverages
[type] => eq_ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 1
[ref] => serofero_mvb.venue_beverages.beverage_id
[rows] => 1
[Extra] =>
)
[9] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => venue_event_options
[type] => ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 4
[ref] => venues.venue_id
[rows] => 2
[Extra] => Using index
)
[10] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => event_options
[type] => eq_ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 1
[ref] => serofero_mvb.venue_event_options.event_option_id
[rows] => 1
[Extra] =>
)
[11] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => venue_styles
[type] => ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 4
[ref] => venues.venue_id
[rows] => 1
[Extra] => Using index
)
[12] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => styles
[type] => eq_ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 1
[ref] => serofero_mvb.venue_styles.style_id
[rows] => 1
[Extra] =>
)
[13] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => venue_space_requirements
[type] => ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 4
[ref] => venues.venue_id
[rows] => 3
[Extra] => Using index
)
[14] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => space_requirements
[type] => eq_ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 1
[ref] => serofero_mvb.venue_space_requirements.space_requirement_id
[rows] => 1
[Extra] =>
)
[15] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => locations
[type] => eq_ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 1
[ref] => venues.location_id
[rows] => 1
[Extra] =>
)
[16] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => venue_features
[type] => ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 4
[ref] => venues.venue_id
[rows] => 7
[Extra] => Using index
)
[17] => Array
(
[id] => 1
[select_type] => PRIMARY
[table] => features
[type] => eq_ref
[possible_keys] => PRIMARY
[key] => PRIMARY
[key_len] => 1
[ref] => serofero_mvb.venue_features.feature_id
[rows] => 1
[Extra] =>
)
[18] => Array
(
[id] => 2
[select_type] => DERIVED
[table] => venues
[type] => ALL
[possible_keys] =>
[key] =>
[key_len] =>
[ref] =>
[rows] => 11
[Extra] =>
)
)
Thankyou
Возможно, вам не хватает индексов. Запустите запрос непосредственно с ключевым словом 'EXPLAIN'. Приведите результат здесь. – datasage
Я никогда не использовал индексы, поэтому я не знал о его силе. И спасибо за представление ключевого слова 'EXPLAIN', я буду использовать Google. Большое спасибо. – Lekhnath
Каждый раз, когда вы соединяете два столбца вместе, каждый столбец должен иметь одинаковый тип данных сопоставления, и оба столбца должны быть проиндексированы. Это позволит mysql сортировать и сопоставлять строки намного быстрее. – datasage