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마리아답:내 쿼리에서 인덱스를 사용하지 않는 이유는 무엇입니까?

projobs 2022. 10. 21. 21:54
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마리아답:내 쿼리에서 인덱스를 사용하지 않는 이유는 무엇입니까?

이 쿼리가 인덱스를 사용하지 않는 이유를 파악하려고 합니다(그래서 매우 깁니다).

explain select count(*) as aggregate 
from `megabase_sms_data_1` 
left join `megabase_sms_thematic_repulse_1` 
    on `megabase_sms_data_1`.`contact_id` = `megabase_sms_thematic_repulse_1`.`megabase_data_id`
where not (megabase_sms_thematic_repulse_1.thematic_id <=> 6) 
    and `age` in ('2', '3', '4', '5', '6', '7', '8', '9', '10', '11', '12', '-1');


+------+-------------+---------------------------------+------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------+---------+-------------------------------------------+----------+-------------+
| id   | select_type | table                           | type | possible_keys                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | key                                                        | key_len | ref                                       | rows     | Extra       |
+------+-------------+---------------------------------+------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------+---------+-------------------------------------------+----------+-------------+
|    1 | SIMPLE      | megabase_sms_data_1             | ALL  | tmp_megabase_sms_data_1_age_index,tmp_megabase_sms_data_1_age_incomes_index,tmp_megabase_sms_data_1_age_housing_zipcode_sex_index,tmp_megabase_sms_data_1_age_zipcode_type_sex_index,tmp_megabase_sms_data_1_age_family_zipcode_sex_index,tmp_megabase_sms_data_1_age_couple_zipcode_sex_index,tmp_megabase_sms_data_1_age_department_sex_housing_index,tmp_megabase_sms_data_1_age_type_department_sex_index,tmp_megabase_sms_data_1_age_family_department_sex_index,tmp_megabase_sms_data_1_age_sex_couple_department_index | NULL                                                       | NULL    | NULL                                      | 20508191 | Using where |
|    1 | SIMPLE      | megabase_sms_thematic_repulse_1 | ref  | tmp_megabase_sms_thematic_repulse_1_megabase_data_id_index                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | tmp_megabase_sms_thematic_repulse_1_megabase_data_id_index | 8       | adsconsole.megabase_sms_data_1.contact_id |        1 | Using where |

contact_id 테이블에 인덱스를 추가하려고 했지만 사용되지 않습니다.내가 개념을 잘못 이해했나 봐.

이 두 개의 테이블이 있습니다.

 DESCRIBE megabase_sms_data_1;
+----------------+------------------+------+-----+---------+----------------+
| Field          | Type             | Null | Key | Default | Extra          |
+----------------+------------------+------+-----+---------+----------------+
| contact_id     | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| sms_md5        | varchar(255)     | NO   | MUL | NULL    |                |
| sms            | varchar(255)     | NO   | MUL | NULL    |                |
| age            | tinyint(4)       | NO   | MUL | NULL    |                |
| sex            | tinyint(4)       | NO   | MUL | NULL    |                |
| couple         | tinyint(4)       | NO   | MUL | NULL    |                |
| family         | tinyint(4)       | NO   | MUL | NULL    |                |
| type           | tinyint(4)       | NO   | MUL | NULL    |                |
| housing        | tinyint(4)       | NO   | MUL | NULL    |                |
| gather_date    | date             | NO   |     | NULL    |                |
| freshness_date | date             | NO   |     | NULL    |                |
| zipcode        | char(5)          | NO   | MUL | NULL    |                |
| department     | char(2)          | NO   | MUL | NULL    |                |
| address        | varchar(255)     | NO   |     | NULL    |                |
| city           | varchar(255)     | NO   |     | NULL    |                |
| latitude       | double           | NO   |     | NULL    |                |
| longitude      | double           | NO   |     | NULL    |                |
| incomes        | tinyint(4)       | NO   | MUL | NULL    |                |
| csp            | tinyint(4)       | NO   |     | NULL    |                |
| adr_iris       | varchar(255)     | NO   |     | NULL    |                |
| adr_inse       | varchar(255)     | NO   |     | NULL    |                |
+----------------+------------------+------+-----+---------+----------------+
21 rows in set (0.00 sec)


 SHOW INDEX FROM megabase_sms_data_1;
+---------------------+------------+----------------------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+                         ---------------+
| Table               | Non_unique | Key_name                                                 | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |                          Index_comment |
+---------------------+------------+----------------------------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+                         ---------------+
| megabase_sms_data_1 |          0 | PRIMARY                                                  |            1 | contact_id  | A         |    20508191 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          0 | tmp_megabase_sms_data_1_contact_id                       |            1 | contact_id  | A         |    20508191 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_sms_md5_index                    |            1 | sms_md5     | A         |    20508191 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_index                        |            1 | age         | A         |          13 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_sex_index                        |            1 | sex         | A         |           3 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_couple_index                     |            1 | couple      | A         |           2 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_family_index                     |            1 | family      | A         |           2 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_type_index                       |            1 | type        | A         |           2 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_housing_index                    |            1 | housing     | A         |           2 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_index                 |            1 | department  | A         |          99 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_incomes_index                    |            1 | incomes     | A         |          10 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_index                    |            1 | zipcode     | A         |       21497 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_incomes_index                |            1 | age         | A         |          13 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_incomes_index                |            2 | incomes     | A         |         131 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_type_age_index                   |            1 | type        | A         |           2 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_type_age_index                   |            2 | age         | A         |          39 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_couple_age_index                 |            1 | couple      | A         |           2 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_couple_age_index                 |            2 | age         | A         |          39 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_family_age_index                 |            1 | family      | A         |           2 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_family_age_index                 |            2 | age         | A         |          39 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_sex_age_index                    |            1 | sex         | A         |           3 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_sex_age_index                    |            2 | age         | A         |          52 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_incomes_age_index                |            1 | incomes     | A         |          10 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_incomes_age_index                |            2 | age         | A         |         131 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_sex_index                |            1 | zipcode     | A         |       21497 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_sex_index                |            2 | sex         | A         |       43266 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_age_index                |            1 | zipcode     | A         |       21497 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_age_index                |            2 | age         | A         |      110259 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_couple_index             |            1 | zipcode     | A         |       21497 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_couple_index             |            2 | couple      | A         |       37085 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_family_index             |            1 | zipcode     | A         |       21497 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_family_index             |            2 | family      | A         |       38261 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_type_index               |            1 | zipcode     | A         |       21497 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_type_index               |            2 | type        | A         |       38549 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_housing_index            |            1 | zipcode     | A         |       21497 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_zipcode_housing_index            |            2 | housing     | A         |       38841 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_sex_index             |            1 | department  | A         |          99 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_sex_index             |            2 | sex         | A         |         396 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_age_index             |            1 | department  | A         |          99 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_age_index             |            2 | age         | A         |        1393 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_couple_index          |            1 | department  | A         |          99 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_couple_index          |            2 | couple      | A         |         299 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_family_index          |            1 | department  | A         |          99 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_family_index          |            2 | family      | A         |         299 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_type_index            |            1 | department  | A         |          99 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_type_index            |            2 | type        | A         |         299 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_housing_index         |            1 | department  | A         |          99 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_department_housing_index         |            2 | housing     | A         |         299 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_housing_zipcode_sex_index    |            1 | age         | A         |          13 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_housing_zipcode_sex_index    |            2 | housing     | A         |          39 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_housing_zipcode_sex_index    |            3 | zipcode     | A         |      253187 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_housing_zipcode_sex_index    |            4 | sex         | A         |      539689 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_zipcode_type_sex_index       |            1 | age         | A         |          13 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_zipcode_type_sex_index       |            2 | zipcode     | A         |      110259 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_zipcode_type_sex_index       |            3 | type        | A         |      256352 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_zipcode_type_sex_index       |            4 | sex         | A         |      554275 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_family_zipcode_sex_index     |            1 | age         | A         |          13 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_family_zipcode_sex_index     |            2 | family      | A         |          39 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_family_zipcode_sex_index     |            3 | zipcode     | A         |      256352 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_family_zipcode_sex_index     |            4 | sex         | A         |      554275 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_couple_zipcode_sex_index     |            1 | age         | A         |          13 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_couple_zipcode_sex_index     |            2 | couple      | A         |          39 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_couple_zipcode_sex_index     |            3 | zipcode     | A         |      250099 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_couple_zipcode_sex_index     |            4 | sex         | A         |      525851 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_department_sex_housing_index |            1 | age         | A         |          13 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_department_sex_housing_index |            2 | department  | A         |        1393 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_department_sex_housing_index |            3 | sex         | A         |        5067 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_department_sex_housing_index |            4 | housing     | A         |       12192 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_type_department_sex_index    |            1 | age         | A         |          13 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_type_department_sex_index    |            2 | type        | A         |          39 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_type_department_sex_index    |            3 | department  | A         |        3913 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_type_department_sex_index    |            4 | sex         | A         |       12207 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_family_department_sex_index  |            1 | age         | A         |          13 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_family_department_sex_index  |            2 | family      | A         |          39 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_family_department_sex_index  |            3 | department  | A         |        3931 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_family_department_sex_index  |            4 | sex         | A         |       11759 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_sex_couple_department_index  |            1 | age         | A         |          13 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_sex_couple_department_index  |            2 | sex         | A         |          52 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_sex_couple_department_index  |            3 | couple      | A         |         132 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_age_sex_couple_department_index  |            4 | department  | A         |       10868 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | tmp_megabase_sms_data_1_sms_index                        |            1 | sms         | A         |     6836063 |     NULL | NULL   |      | BTREE      |         |                                        |
| megabase_sms_data_1 |          1 | contact_id                                               |            1 | contact_id  | A         |    20508191 |     NULL | NULL   |      | BTREE      |         |                                        |

그리고 두 번째는:

describe megabase_sms_thematic_repulse_1;
+------------------+------------+------+-----+---------+-------+
| Field            | Type       | Null | Key | Default | Extra |
+------------------+------------+------+-----+---------+-------+
| megabase_data_id | bigint(20) | NO   | MUL | NULL    |       |
| thematic_id      | int(11)    | NO   | MUL | NULL    |       |
+------------------+------------+------+-----+---------+-------+
2 rows in set (0.00 sec)

 SHOW INDEX FROM megabase_sms_thematic_repulse_1;
+---------------------------------+------------+------------------------------------------------------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table                           | Non_unique | Key_name                                                   | Seq_in_index | Column_name      | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------------------------------+------------+------------------------------------------------------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| megabase_sms_thematic_repulse_1 |          1 | tmp_megabase_sms_thematic_repulse_1_megabase_data_id_index |            1 | megabase_data_id | A         |           3 |     NULL | NULL   |      | BTREE      |         |               |
| megabase_sms_thematic_repulse_1 |          1 | tmp_megabase_sms_thematic_repulse_1_thematic_id_index      |            1 | thematic_id      | A         |           1 |     NULL | NULL   |      | BTREE      |         |               |
+---------------------------------+------------+------------------------------------------------------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+

내가 뭘 잘못하고 있지?쿼리 또는 데이터베이스 구조를 최적화하려면 어떻게 해야 합니까?

정말 감사해요.

쿼리가 반환되는 행 수에 따라 mysql은 인덱스를 사용하는 대신 전체 스캔을 사용하는 것이 더 효율적이라고 추정할 수 있습니다.

원인을 좁히려면 where 구를 지정하지 않고 쿼리를 실행하여 인덱스가 사용되고 있는지 확인합니다.그런 다음 where 절을 하나씩 추가하여 어느 절이 인덱스를 사용하지 않는지 확인합니다.Where 절이 너무 일반적일 수 있으므로 인덱스를 사용하는 대신 전체 테이블 검색을 수행하는 것이 더 효율적입니다.

연령으로 인해 인덱스가 사용되지 않는 경우 contact_id + age에 인덱스를 생성할 수 있습니다.

에 참가하고 있습니다.megabase_sms_data_1.contact_id및 필터링megabase_sms_data_1.age따라서 두 열을 모두 포함하는 인덱스를 생성해야 하며 테이블당 하나의 인덱스만 사용할 수 있습니다. 현재 조인 또는 필터를 지원할 수 있지만 둘 다 지원할 수는 없습니다.데이터베이스 쿼리 옵티마이저는 풀 테이블스캔을 사용할지 여부를 결정할 수 있습니다.

쿼리 시도 지원:

alter table megabase_sms_data_1 add index test(contact_id, age)

또는

alter table megabase_sms_data_1 add index test(age, contact_id)

언급URL : https://stackoverflow.com/questions/48719673/mariadb-why-my-queries-is-not-using-the-indexes

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