2
나는 매우 이상한 MySQL의 행동을 발견 : 나는 두 번 특정 쿼리를 실행할 때이 두 번째 다른이 쿼리의 설명 :정확하게 똑같은 mysql 질의는 2 가지 'explain'결과를 준다 : 왜?
query = SELECT `twstats_twwordstrend`.`id`, `twstats_twwordstrend`.`created`, `twstats_twwordstrend`.`freq`, `twstats_twwordstrend`.`word_id` FROM `twstats_twwordstrend` INNER JOIN `twstats_twwords` ON (`twstats_twwordstrend`.`word_id` = `twstats_twwords`.`id`) WHERE (`twstats_twwords`.`name` = '@ladygaga' AND `twstats_twwordstrend`.`created` > '2011-01-28 01:30:19');
1st query execution and then run explain :
mysql> EXPLAIN SELECT `twstats_twwordstrend`.`id`, `twstats_twwordstrend`.`created`, `twstats_twwordstrend`.`freq`, `twstats_twwordstrend`.`word_id` FROM `twstats_twwordstrend` INNER JOIN `twstats_twwords` ON (`twstats_twwordstrend`.`word_id` = `twstats_twwords`.`id`) WHERE (`twstats_twwords`.`name` = '@ladygaga' AND `twstats_twwordstrend`.`created` > '2011-01-28 01:30:19');
+----+-------------+----------------------+--------+-------------------------------+---------+---------+-------------------------------------------+---------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+----------------------+--------+-------------------------------+---------+---------+-------------------------------------------+---------+-------------+
| 1 | SIMPLE | twstats_twwordstrend | ALL | twstats_twwordstrend_4b95d890 | NULL | NULL | NULL | 4877401 | Using where |
| 1 | SIMPLE | twstats_twwords | eq_ref | PRIMARY | PRIMARY | 4 | statweestics.twstats_twwordstrend.word_id | 1 | Using where |
+----+-------------+----------------------+--------+-------------------------------+---------+---------+-------------------------------------------+---------+-------------+
2 rows in set (0.00 sec)
2nd query execution and then run explain :
mysql> EXPLAIN SELECT `twstats_twwordstrend`.`id`, `twstats_twwordstrend`.`created`, `twstats_twwordstrend`.`freq`, `twstats_twwordstrend`.`word_id` FROM `twstats_twwordstrend` INNER JOIN `twstats_twwords` ON (`twstats_twwordstrend`.`word_id` = `twstats_twwords`.`id`) WHERE (`twstats_twwords`.`name` = '@ladygaga' AND `twstats_twwordstrend`.`created` > '2011-01-28 01:30:19');
+----+-------------+----------------------+------+-------------------------------+-------------------------------+---------+---------------------------------+--------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+----------------------+------+-------------------------------+-------------------------------+---------+---------------------------------+--------+-------------+
| 1 | SIMPLE | twstats_twwords | ALL | PRIMARY | NULL | NULL | NULL | 222994 | Using where |
| 1 | SIMPLE | twstats_twwordstrend | ref | twstats_twwordstrend_4b95d890 | twstats_twwordstrend_4b95d890 | 4 | statweestics.twstats_twwords.id | 15 | Using where |
+----+-------------+----------------------+------+-------------------------------+-------------------------------+---------+---------------------------------+--------+-------------+
2 rows in set (0.00 sec)
mysql> describe twstats_twwords;
+---------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| created | datetime | NO | | NULL | |
| name | varchar(140) | NO | | NULL | |
+---------+--------------+------+-----+---------+----------------+
3 rows in set (0.00 sec)
mysql> describe twstats_twwordstrend;
+---------+----------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+----------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| created | datetime | NO | | NULL | |
| freq | double | NO | | NULL | |
| word_id | int(11) | NO | MUL | NULL | |
+---------+----------+------+-----+---------+----------------+
4 rows in set (0.00 sec)
것은이 가능할 수있는 방법은?
후 결과 표 twstats_twwords'를 작성, – Timur
는 TABLE'twstats_twwords'을 만드십시오 ( 'id'의 INT (11) NOT NULL AUTO_INCREMENT, 'created' 날짜 NOT NULL, 'name'의 VARCHAR (140) NOT NULL, PRIMARY KEY ('id'), UNIQUE KEY'name' ('name') <-이 게시물이 내 게시물 뒤에 추가되었습니다 ( ) ENGINE = InnoDB AUTO_INCREMENT = 225038 DEFAULT CHARSET = utf8 – Eric