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我有我的数据库中有61K行mysql
,我试着做一个计数,但查询需要4秒,我认为它太多了。计数查询需要很多时间
select count(distinct appeloffre0_.ID_APPEL_OFFRE)
from ao.appel_offre appeloffre0_
inner join ao.lot lots1_ on appeloffre0_.ID_APPEL_OFFRE=lots1_.ID_APPEL_OFFRE
inner join ao.lieu_execution lieuexecut2_ on appeloffre0_.ID_APPEL_OFFRE=lieuexecut2_.appel_offre
inner join ao.acheteur acheteur3_ on appeloffre0_.ID_ACHETEUR=acheteur3_.ID_ACHETEUR
inner join ao.ao_activite aoactivite4_ on appeloffre0_.ID_APPEL_OFFRE=aoactivite4_.ID_APPEL_OFFRE
我的查询结果:
+----------------------------------------------+
| count(distinct appeloffre0_.ID_APPEL_OFFRE) |
+----------------------------------------------+
| 61100 |
+----------------------------------------------+
1 row in set (4.35 sec)
为什么explain
CMD表appeloffre0_
使用关键appel_offre_ibfk_2
这是对FK列ID_ACHETEUR
一个指数?
+----+-------------+--------------+--------+----------------------------+--------------------+---------+--------------------------------+-------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+--------------+--------+----------------------------+--------------------+---------+--------------------------------+-------+--------------------------+
| 1 | SIMPLE | appeloffre0_ | index | PRIMARY,appel_offre_ibfk_2 | appel_offre_ibfk_2 | 4 | NULL | 60031 | Using index |
| 1 | SIMPLE | acheteur3_ | eq_ref | PRIMARY | PRIMARY | 4 | ao.appeloffre0_.ID_ACHETEUR | 1 | Using index |
| 1 | SIMPLE | lieuexecut2_ | ref | fk_ao_lieuex | fk_ao_lieuex | 4 | ao.appeloffre0_.ID_APPEL_OFFRE | 1 | Using index |
| 1 | SIMPLE | aoactivite4_ | ref | ao_activites_ao_fk | ao_activites_ao_fk | 4 | ao.lieuexecut2_.appel_offre | 3 | Using where; Using index |
| 1 | SIMPLE | lots1_ | ref | FK_LOT_AO | FK_LOT_AO | 4 | ao.lieuexecut2_.appel_offre | 5 | Using where; Using index |
+----+-------------+--------------+--------+----------------------------+--------------------+---------+--------------------------------+-------+--------------------------+
5 rows in set (0.00 sec)
节目从appel_offre
+-------------+------------+--------------------+--------------+---------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------------+------------+--------------------+--------------+---------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| appel_offre | 0 | PRIMARY | 1 | ID_APPEL_OFFRE | A | 60953 | NULL | NULL | | BTREE | | |
| appel_offre | 1 | appel_offre_ibfk_1 | 1 | ID_APPEL_OFFRE_MERE | A | 2 | NULL | NULL | YES | BTREE | | |
| appel_offre | 1 | appel_offre_ibfk_2 | 1 | ID_ACHETEUR | A | 2 | NULL | NULL | | BTREE | | |
| appel_offre | 1 | appel_offre_ibfk_3 | 1 | USER_SAISIE | A | 2 | NULL | NULL | YES | BTREE | | |
| appel_offre | 1 | appel_offre_ibfk_4 | 1 | USER_VALIDATION | A | 2 | NULL | NULL | YES | BTREE | | |
| appel_offre | 1 | ao_fk_3 | 1 | TYPE_MARCHE | A | 2 | NULL | NULL | YES | BTREE | | |
| appel_offre | 1 | ao_fk_5 | 1 | USER_CONTROLE | A | 2 | NULL | NULL | YES | BTREE | | |
+-------------+------------+--------------------+--------------+---------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
7 rows in set (0.03 sec)
如何使用指数跑得快数查询索引?
如何在我们有多个连接时使用索引?
如何使用索引当我们有多个连接和多个搜索 查询?
感谢@FuzzyTree它减少我的时间0.7秒,你能回答我的2点和3点吗?因为我将使用多重连接的多标准搜索。如果可以的话,你可以给我一个很好的答案。 – Youssef
@Youssef根据你的解释输出,它看起来像你已经正确地使用索引与您的多个加入/其中条件 – FuzzyTree
似乎在添加一些where子句后需要时间再次检查它在这里http://stackoverflow.com/questions/ 27784778 /慢计数查询与-where子句 – Youssef