質問編集履歴
2
追加情報
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###追加情報
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###追加情報1
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) ENGINE=InnoDB AUTO_INCREMENT=45097 DEFAULT CHARSET=utf8mb4 |
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###追加情報2
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**offsetの数が大きくなるほど遅くなります**
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offsetの数が49700の場合は6秒もかかってしまいました
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```MySQL
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mysql> select * from `repositories` where `stars_per_day` is not null and `repositories`.`checked_at` > '2016-12-13 11:59:34.000000' order by `stars_per_day` desc limit 10 offset 49700;
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10 rows in set (6.50 sec)
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```
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offsetの数が0の場合は爆速です
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```ここに言語を入力
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mysql> select * from `repositories` where `stars_per_day` is not null and `repositories`.`checked_at` > '2016-12-13 11:59:34.000000' order by `stars_per_day` desc limit 10 offset 0;
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10 rows in set (0.01 sec)
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```
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**Extraは変わりありませんでした**
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force indexを付け加えた場合
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```ここに言語を入力
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mysql> explain select * from `repositories` force index (idx_1) where `stars_per_day` is not null and `repositories`.`checked_at` > '2016-12-13 11:59:34.000000' order by `stars_per_day` desc limit 10 offset 49700;
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+----+-------------+--------------+------------+-------+---------------+-------+---------+------+-------+----------+-----------------------+
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| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+----+-------------+--------------+------------+-------+---------------+-------+---------+------+-------+----------+-----------------------+
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| 1 | SIMPLE | repositories | NULL | range | idx_1 | idx_1 | 5 | NULL | 19628 | 33.33 | Using index condition |
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+----+-------------+--------------+------------+-------+---------------+-------+---------+------+-------+----------+-----------------------+
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1 row in set, 1 warning (0.00 sec)
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```
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force indexを付け加えない場合
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```ここに言語を入力
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mysql> explain select * from `repositories` where `stars_per_day` is not null and `repositories`.`checked_at` > '2016-12-13 11:59:34.000000' order by `stars_per_day` desc limit 10 offset 49700;
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+----+-------------+--------------+------------+-------+---------------+-------+---------+------+-------+----------+-----------------------+
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| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+----+-------------+--------------+------------+-------+---------------+-------+---------+------+-------+----------+-----------------------+
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| 1 | SIMPLE | repositories | NULL | range | idx_1,idx_2 | idx_1 | 5 | NULL | 19628 | 50.00 | Using index condition |
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+----+-------------+--------------+------------+-------+---------------+-------+---------+------+-------+----------+-----------------------+
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1 row in set, 1 warning (0.00 sec)
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```
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1
情報追加
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test
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```
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###追加情報
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データーベース情報は以下のようになりました。何故かMySQLクライアントからだと高速に発行できます
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```Mysql
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mysql> EXPLAIN select count(*) as aggregate from `repositories` where `stars_per_day` is not null and `repositories`.`checked_at` > '2016-12-13 07:48:38.000000';
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+----+-------------+--------------+------------+-------+--------------------------+---------------+---------+------+-------+----------+-----------------------------------------------+
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| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+----+-------------+--------------+------------+-------+--------------------------+---------------+---------+------+-------+----------+-----------------------------------------------+
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| 1 | SIMPLE | repositories | NULL | range | stars_per_day,checked_at | stars_per_day | 5 | NULL | 16287 | 50.00 | Using index condition; Using where; Using MRR |
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+----+-------------+--------------+------------+-------+--------------------------+---------------+---------+------+-------+----------+-----------------------------------------------+
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1 row in set, 1 warning (0.00 sec)
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mysql> EXPLAIN select * from `repositories` where `stars_per_day` is not null and `repositories`.`checked_at` > '2016-12-13 07:48:38.000000' order by `stars_per_day` desc limit 10 offset 0;
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+----+-------------+--------------+------------+-------+--------------------------+---------------+---------+------+-------+----------+------------------------------------+
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| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+----+-------------+--------------+------------+-------+--------------------------+---------------+---------+------+-------+----------+------------------------------------+
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| 1 | SIMPLE | repositories | NULL | range | stars_per_day,checked_at | stars_per_day | 5 | NULL | 16287 | 50.00 | Using index condition; Using where |
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+----+-------------+--------------+------------+-------+--------------------------+---------------+---------+------+-------+----------+------------------------------------+
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1 row in set, 1 warning (0.01 sec)
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mysql> show create table repositories;
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| repositories | CREATE TABLE `repositories` (
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`id` int(11) NOT NULL AUTO_INCREMENT,
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`repository_id` int(11) NOT NULL,
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`full_name` varchar(255) DEFAULT NULL,
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`name` varchar(255) DEFAULT NULL,
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`master_branch` varchar(255) DEFAULT NULL,
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`readme` longtext,
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`stargazers_count` int(11) DEFAULT NULL,
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`language_id` int(11) DEFAULT NULL,
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`description` longtext,
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`description_ja` longtext,
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`homepage` longtext,
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`created_at` datetime DEFAULT NULL,
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`updated_at` datetime DEFAULT NULL,
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`pushed_at` datetime DEFAULT NULL,
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`stars_per_day` float DEFAULT NULL,
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`similar_repositories` longtext,
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`checked_at` datetime DEFAULT NULL,
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`avatar_url` longtext,
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PRIMARY KEY (`id`),
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UNIQUE KEY `repositories_repository_id` (`repository_id`),
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KEY `stars_per_day` (`stars_per_day`),
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KEY `checked_at` (`checked_at`),
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FULLTEXT KEY `repositories` (`full_name`,`name`,`description`)
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) ENGINE=InnoDB AUTO_INCREMENT=45097 DEFAULT CHARSET=utf8mb4 |
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```
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