1我们先回顾一下使用复合索引的几个条件
使用索引排序最好是满足一下两个条件
下面进行一些例子
下面举一个生产上的例子
我们更改一下sql语句
现在返回去思考为什么会出现filesort排序
filesort排序定义：表示 MySQL 会对结果使用一个外部索引排序,而不是从表里按索引次序读到相关内容。可能在内存或者磁盘上进行排序。MySQL 中无法利用索引完成的排序操作称为“文件排序（filesort）
高性能mysqlP222页
mysql架构设计与优化155页
关于groupby 排序可以查看mysql性能调优与架构设计（P160）
排序条件和order by的条件一样~~并且还必须满足：使用group by的同时只能使用max 和min 两个聚合函数
关于or的优化（用到了索引的全表扫描，虽然联合索引两个字段都用到了，碰到这种还是分开写成两条语句吧，然后每个字段建个索引）
MySQL [ngx_log]> explain select * from tt where age=3 or score=6;
+----+-------------+-------+-------+-------------------------+---------------+---------+------+------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------+-------------------------+---------------+---------+------+------+--------------------------+
| 1 | SIMPLE | tt | index | idx_age_score,idx_score | idx_age_score | 10 | NULL | 20 | Using where; Using index |
+----+-------------+-------+-------+-------------------------+---------------+---------+------+------+--------------------------+
1 row in set (0.00 sec)
有时会这样（优化器进行了索引合并，这样效果还是比较好的，联合索引Uid_c_uid(只用到了uid字段) 和c_uid这个索引）
点击(此处)折叠或打开
- 如果不是使用索引的最左列，则无法使用索引
- 不能跳过索引中的列，如select * from tab where a=** and c=***，则只能用到索引的第一列a
- 如果查询中的莫个列有范围查询，则右边的列都无法使用索引，如：select * from tab where a= and b> and c= 则索引只能用到a,b列
使用索引排序最好是满足一下两个条件
- 1.只有当索引的列顺序与order by 子句的顺序完全一致，并且所有列的排序方向（倒叙或者正序）都一样时，mysql才能够使用索引来对结果进行排序。
-
- 2.如果查询需要关联多张表的时候，则只有当order by子句引用的字段全部为第一张表时，才能使用索引排序，order by子句和查找型查询的限制是一样的：需要满足索引的最左前缀的要求，否则无法利用索引排序，有一种情况order by 子句可以不满足索引的最左前缀的要求，就是前导列为常量的时候，
-
- 修改：满足的索引必须是执行计划中的索引啊，，，
下面进行一些例子
- 背景：复合索引（a,b,c）
1.select * from tab where a=‘9878’ order by b； ---可以，因为最左前缀提供了常量，ab组合就形成了最左前缀，explain查看只使用了复合索引的（a)列，但是排序时用到了b列
2.select * from tab where a> order by a,b; ---可以，（a,b）满足最左前缀 ，，，explain查看只使用了复合索引的（a)列，但是排序时用到了b列
下面这些就不行了
select * from tab where a='asad' order by b desc,c asc; ---排序不一样
select * from tab where a='adad' order by b,d; ----引用非索引字段
select * from tab where a='adsad' order by c; ----（a,c)组合跳过b列
select * from tab where a> order b,c; -----a是范围查询，索引只能用到a列
select * from tab where a= and b in () order by c; -----b列范围查询，其右边的字段用不到了，只能用到 ab列
select * from tab where
一个面试题：
A：（c1,c2,c3,c4)
B:(c1,c2),排序用到c3
C:(c1)
D:(c1) 排序用到c2 c3
E:(c1,c2) 排序用到c3
题中的？如果代表的是非常量的意思，那么我们就选B吧！
----这个理论上是可以使用索引进行关联排序的，满足第二个条件嘛：a既满足来自第一张表，也满足最左前缀，但是优化器选择时将table1表当作了第二张关联表，所以实际上无法使用索引了！
select * from table1，table2 where table1.id=table2.id order by a;
2.select * from tab where a> order by a,b; ---可以，（a,b）满足最左前缀 ，，，explain查看只使用了复合索引的（a)列，但是排序时用到了b列
下面这些就不行了
select * from tab where a='asad' order by b desc,c asc; ---排序不一样
select * from tab where a='adad' order by b,d; ----引用非索引字段
select * from tab where a='adsad' order by c; ----（a,c)组合跳过b列
select * from tab where a> order b,c; -----a是范围查询，索引只能用到a列
select * from tab where a= and b in () order by c; -----b列范围查询，其右边的字段用不到了，只能用到 ab列
select * from tab where
一个面试题：
A：（c1,c2,c3,c4)
B:(c1,c2),排序用到c3
C:(c1)
D:(c1) 排序用到c2 c3
E:(c1,c2) 排序用到c3
题中的？如果代表的是非常量的意思，那么我们就选B吧！
----这个理论上是可以使用索引进行关联排序的，满足第二个条件嘛：a既满足来自第一张表，也满足最左前缀，但是优化器选择时将table1表当作了第二张关联表，所以实际上无法使用索引了！
select * from table1，table2 where table1.id=table2.id order by a;
下面举一个生产上的例子
点击(此处)折叠或打开
-
mysql> explain SELECT payment.id,payment.money,payment.c_time,payment.card_type,b_member_card.active_time,b_users.name,b_users.tel,zone.zone_name,admin.name as admin_name,admin.role_id,b_card_info.card_name as ccname FROM `payment` LEFT JOIN b_member_card ON b_member_card.payid=payment.id LEFT JOIN b_users ON payment.xdy_id=b_users.uid LEFT JOIN zone ON payment.zone_id=zone.zone_id LEFT JOIN admin ON payment.sale_id=admin.id LEFT JOIN b_card_info ON payment.vip_card = b_card_info.id WHERE ( `sale_id` IN ('39','110','159','311','349','353','362','432','449','450','489','501','533','562') ) AND ( `payed` = 2 ) ORDER BY payment.id desc LIMIT 0,10;
-
+----+-------------+---------------+--------+---------------+---------------+---------+---------------------------------------+------+-----------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------+--------+---------------+---------------+---------+---------------------------------------+------+-----------------------------+
| 1 | SIMPLE | payment | range | sale_id_payed | sale_id_payed | 5 | NULL | 40 | Using where; Using filesort | ---为什么会出现filesort
| 1 | SIMPLE | b_member_card | ref | payid | payid | 5 | interface_hd_com0624.payment.id | 1 | |
| 1 | SIMPLE | b_users | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.xdy_id | 1 | |
| 1 | SIMPLE | zone | eq_ref | PRIMARY | PRIMARY | 3 | interface_hd_com0624.payment.zone_id | 1 | |
| 1 | SIMPLE | admin | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.sale_id | 1 | |
| 1 | SIMPLE | b_card_info | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.vip_card | 1 | |
+----+-------------+---------------+--------+---------------+---------------+---------+---------------------------------------+------+-----------------------------+
- 6 rows in set (0.00 sec)
- 。
- 查看索引
-
mysql> show index from payment;
+---------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| payment | 0 | PRIMARY | 1 | id | A | 3173 | NULL | NULL | | BTREE | | |
| payment | 1 | sale_id_payed | 1 | sale_id | A | 137 | NULL | NULL | | BTREE | | |
| payment | 1 | sale_id_payed | 2 | payed | A | 244 | NULL | NULL | | BTREE | | |
+---------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
3 rows in set (0.04 sec)
- 为什么上面会出现filesort这种情况呢？id来之于执行计划的第一张表，又是主键，完全满足上面索引排序的要求啊，但是为啥没用到索引排序呢？
我们更改一下sql语句
- mysql> explain SELECT payment.id,payment.money,payment.c_time,payment.card_type,b_member_card.active_time,b_users.name,b_users.tel,zone.zone_name,admin.name as admin_name,admin.role_id,b_card_info.card_name as ccname FROM `payment` LEFT JOIN b_member_card ON b_member_card.payid=payment.id LEFT JOIN b_users ON payment.xdy_id=b_users.uid LEFT JOIN zone ON payment.zone_id=zone.zone_id LEFT JOIN admin ON payment.sale_id=admin.id LEFT JOIN b_card_info ON payment.vip_card = b_card_info.id WHERE ( `sale_id` IN ('39','110','159','311','349','353','362','432','449','450','489','501','533','562') ) AND ( `payed` = 2 ) ORDER BY payment.payed desc LIMIT 0,10
-
+----+-------------+---------------+--------+---------------+---------------+---------+---------------------------------------+------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------+--------+---------------+---------------+---------+---------------------------------------+------+-------------+
| 1 | SIMPLE | payment | range | sale_id_payed | sale_id_payed | 5 | NULL | 40 | Using where | --排序条件改成payed就好了
| 1 | SIMPLE | b_member_card | ref | payid | payid | 5 | interface_hd_com0624.payment.id | 1 | |
| 1 | SIMPLE | b_users | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.xdy_id | 1 | |
| 1 | SIMPLE | zone | eq_ref | PRIMARY | PRIMARY | 3 | interface_hd_com0624.payment.zone_id | 1 | |
| 1 | SIMPLE | admin | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.sale_id | 1 | |
| 1 | SIMPLE | b_card_info | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.vip_card | 1 | |
+----+-------------+---------------+--------+---------------+---------------+---------+---------------------------------------+-----
观察上面两条sql你可以发现：要想使用索引排序你得满足下面的条件
：在满足最上面两个条件的的基础上
：附加：order by col的col还必须是满足执行计划中的用到的索引的最左前缀条件
根据这些要求我们可以将sale_id_payed索引的范围拓展一点至id 删除原来的索引新建：create index sale_id_payed_id on payment(id,sale_id,payed);
mysql> explain SELECT payment.id,payment.money,payment.c_time,payment.card_type,b_member_card.active_time,b_users.name,b_users.tel,zone.zone_name,admin.name as admin_name,admin.role_id,b_card_info.card_name as ccname FROM `payment` LEFT JOIN b_member_card ON b_member_card.payid=payment.id LEFT JOIN b_users ON payment.xdy_id=b_users.uid LEFT JOIN zone ON payment.zone_id=zone.zone_id LEFT JOIN admin ON payment.sale_id=admin.id LEFT JOIN b_card_info ON payment.vip_card = b_card_info.id WHERE ( `sale_id` IN ('39','110','159','311','349','353','362','432','449','450','489','501','533','562') ) AND ( `payed` = 2 ) ORDER BY payment.id desc LIMIT 0,10;
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+-------------+
| 1 | SIMPLE | payment | index | NULL | PRIMARY | 4 | NULL | 10 | Using where | ---比上面的优化更好了一下，用到主键索引了
| 1 | SIMPLE | b_member_card | ref | payid | payid | 5 | interface_hd_com0624.payment.id | 1 | |
| 1 | SIMPLE | b_users | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.xdy_id | 1 | |
| 1 | SIMPLE | zone | eq_ref | PRIMARY | PRIMARY | 3 | interface_hd_com0624.payment.zone_id | 1 | |
| 1 | SIMPLE | admin | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.sale_id | 1 | |
| 1 | SIMPLE | b_card_info | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.vip_card | 1 | |
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+-------------+
6 rows in set (0.00 sec)
：在满足最上面两个条件的的基础上
：附加：order by col的col还必须是满足执行计划中的用到的索引的最左前缀条件
根据这些要求我们可以将sale_id_payed索引的范围拓展一点至id 删除原来的索引新建：create index sale_id_payed_id on payment(id,sale_id,payed);
mysql> explain SELECT payment.id,payment.money,payment.c_time,payment.card_type,b_member_card.active_time,b_users.name,b_users.tel,zone.zone_name,admin.name as admin_name,admin.role_id,b_card_info.card_name as ccname FROM `payment` LEFT JOIN b_member_card ON b_member_card.payid=payment.id LEFT JOIN b_users ON payment.xdy_id=b_users.uid LEFT JOIN zone ON payment.zone_id=zone.zone_id LEFT JOIN admin ON payment.sale_id=admin.id LEFT JOIN b_card_info ON payment.vip_card = b_card_info.id WHERE ( `sale_id` IN ('39','110','159','311','349','353','362','432','449','450','489','501','533','562') ) AND ( `payed` = 2 ) ORDER BY payment.id desc LIMIT 0,10;
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+-------------+
| 1 | SIMPLE | payment | index | NULL | PRIMARY | 4 | NULL | 10 | Using where | ---比上面的优化更好了一下，用到主键索引了
| 1 | SIMPLE | b_member_card | ref | payid | payid | 5 | interface_hd_com0624.payment.id | 1 | |
| 1 | SIMPLE | b_users | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.xdy_id | 1 | |
| 1 | SIMPLE | zone | eq_ref | PRIMARY | PRIMARY | 3 | interface_hd_com0624.payment.zone_id | 1 | |
| 1 | SIMPLE | admin | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.sale_id | 1 | |
| 1 | SIMPLE | b_card_info | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.vip_card | 1 | |
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+-------------+
6 rows in set (0.00 sec)
现在返回去思考为什么会出现filesort排序
filesort排序定义：表示 MySQL 会对结果使用一个外部索引排序,而不是从表里按索引次序读到相关内容。可能在内存或者磁盘上进行排序。MySQL 中无法利用索引完成的排序操作称为“文件排序（filesort）
高性能mysqlP222页
mysql架构设计与优化155页
- 1.如果order by子句中的col都是来自于第一张表（但不满足索引排序的条件），那么mysql在关联处理第一个表时就会进行文件的排序。那么我们在explain的extra字段中就会看到useing filesort
mysql> explain SELECT payment.id,payment.money,payment.c_time,payment.card_type,b_member_card.active_time,b_users.name,b_users.tel,zone.zone_name,admin.name as admin_name,admin.role_id,b_card_info.card_name as ccname FROM `payment` LEFT JOIN b_member_card ON b_member_card.payid=payment.id LEFT JOIN b_users ON payment.xdy_id=b_users.uid LEFT JOIN zone ON payment.zone_id=zone.zone_id LEFT JOIN admin ON payment.sale_id=admin.id LEFT JOIN b_card_info ON payment.vip_card = b_card_info.id WHERE ( `sale_id` IN ('39','110','159','311','349','353','362','432','449','450','489','501','533','562') ) AND ( `payed` = 2 ) ORDER BY id,money desc LIMIT 0,10;
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+-----------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+-----------------------------+
| 1 | SIMPLE | payment | ALL | NULL | NULL | NULL | NULL | 2965 | Using where; Using filesort |
| 1 | SIMPLE | b_member_card | ref | payid | payid | 5 | interface_hd_com0624.payment.id | 309 | |
| 1 | SIMPLE | b_users | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.xdy_id | 1 | |
| 1 | SIMPLE | zone | eq_ref | PRIMARY | PRIMARY | 3 | interface_hd_com0624.payment.zone_id | 1 | |
| 1 | SIMPLE | admin | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.sale_id | 1 | |
| 1 | SIMPLE | b_card_info | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.vip_card | 1 | |
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+-----------------------------+
2，除了上面的情况外，explain的extra字段都会看到use tempory；using filesort的情况
mysql> explain SELECT payment.id,payment.money,payment.c_time,payment.card_type,b_member_card.active_time,b_users.name,b_users.tel,zone.zone_name,admin.name as admin_name,admin.role_id,b_card_info.card_name as ccname FROM `payment` LEFT JOIN b_member_card ON b_member_card.payid=payment.id LEFT JOIN b_users ON payment.xdy_id=b_users.uid LEFT JOIN zone ON payment.zone_id=zone.zone_id LEFT JOIN admin ON payment.sale_id=admin.id LEFT JOIN b_card_info ON payment.vip_card = b_card_info.id WHERE ( `sale_id` IN ('39','110','159','311','349','353','362','432','449','450','489','501','533','562') ) AND ( `payed` = 2 ) ORDER BY id,money,b_users.name desc LIMIT 0,10;
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+----------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+----------------------------------------------+
| 1 | SIMPLE | payment | ALL | NULL | NULL | NULL | NULL | 2965 | Using where; Using temporary; Using filesort |
| 1 | SIMPLE | b_member_card | ref | payid | payid | 5 | interface_hd_com0624.payment.id | 309 | |
| 1 | SIMPLE | b_users | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.xdy_id | 1 | |
| 1 | SIMPLE | zone | eq_ref | PRIMARY | PRIMARY | 3 | interface_hd_com0624.payment.zone_id | 1 | |
| 1 | SIMPLE | admin | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.sale_id | 1 | |
| 1 | SIMPLE | b_card_info | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.vip_card | 1 | |
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+----------------------------------------------+
6 rows in set (0.00 sec)
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+-----------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+-----------------------------+
| 1 | SIMPLE | payment | ALL | NULL | NULL | NULL | NULL | 2965 | Using where; Using filesort |
| 1 | SIMPLE | b_member_card | ref | payid | payid | 5 | interface_hd_com0624.payment.id | 309 | |
| 1 | SIMPLE | b_users | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.xdy_id | 1 | |
| 1 | SIMPLE | zone | eq_ref | PRIMARY | PRIMARY | 3 | interface_hd_com0624.payment.zone_id | 1 | |
| 1 | SIMPLE | admin | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.sale_id | 1 | |
| 1 | SIMPLE | b_card_info | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.vip_card | 1 | |
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+-----------------------------+
2，除了上面的情况外，explain的extra字段都会看到use tempory；using filesort的情况
mysql> explain SELECT payment.id,payment.money,payment.c_time,payment.card_type,b_member_card.active_time,b_users.name,b_users.tel,zone.zone_name,admin.name as admin_name,admin.role_id,b_card_info.card_name as ccname FROM `payment` LEFT JOIN b_member_card ON b_member_card.payid=payment.id LEFT JOIN b_users ON payment.xdy_id=b_users.uid LEFT JOIN zone ON payment.zone_id=zone.zone_id LEFT JOIN admin ON payment.sale_id=admin.id LEFT JOIN b_card_info ON payment.vip_card = b_card_info.id WHERE ( `sale_id` IN ('39','110','159','311','349','353','362','432','449','450','489','501','533','562') ) AND ( `payed` = 2 ) ORDER BY id,money,b_users.name desc LIMIT 0,10;
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+----------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+----------------------------------------------+
| 1 | SIMPLE | payment | ALL | NULL | NULL | NULL | NULL | 2965 | Using where; Using temporary; Using filesort |
| 1 | SIMPLE | b_member_card | ref | payid | payid | 5 | interface_hd_com0624.payment.id | 309 | |
| 1 | SIMPLE | b_users | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.xdy_id | 1 | |
| 1 | SIMPLE | zone | eq_ref | PRIMARY | PRIMARY | 3 | interface_hd_com0624.payment.zone_id | 1 | |
| 1 | SIMPLE | admin | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.sale_id | 1 | |
| 1 | SIMPLE | b_card_info | eq_ref | PRIMARY | PRIMARY | 4 | interface_hd_com0624.payment.vip_card | 1 | |
+----+-------------+---------------+--------+---------------+---------+---------+---------------------------------------+------+----------------------------------------------+
6 rows in set (0.00 sec)
关于groupby 排序可以查看mysql性能调优与架构设计（P160）
排序条件和order by的条件一样~~并且还必须满足：使用group by的同时只能使用max 和min 两个聚合函数
关于or的优化（用到了索引的全表扫描，虽然联合索引两个字段都用到了，碰到这种还是分开写成两条语句吧，然后每个字段建个索引）
MySQL [ngx_log]> explain select * from tt where age=3 or score=6;
+----+-------------+-------+-------+-------------------------+---------------+---------+------+------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------+-------------------------+---------------+---------+------+------+--------------------------+
| 1 | SIMPLE | tt | index | idx_age_score,idx_score | idx_age_score | 10 | NULL | 20 | Using where; Using index |
+----+-------------+-------+-------+-------------------------+---------------+---------+------+------+--------------------------+
1 row in set (0.00 sec)
有时会这样（优化器进行了索引合并，这样效果还是比较好的，联合索引Uid_c_uid(只用到了uid字段) 和c_uid这个索引）
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/29096438/viewspace-1839593/ ，如需转载，请注明出处，否则将追究法律责任。
请登录后发表评论
登录
全部评论
最新文章
- [Mysql]Mysql5.7并行复制
- 【Redis】错误：failed: Hostname must not be empty or null
- 【Python】python map()函数和lambda表达式
- 【Mysql】MySQL中interactive_timeout和wait_timeout的区别
- 【Mysql】修改mysql时区
- MySQL(Innodb)索引的原理
- 【Redis】修改redis-trib.rb使其import支持密码
- 【Redis】redis-cluster需要注意的几个地方
- 【Mongodb】mongo复制集只剩一个secondery节点的解决办法
- 【Redis】redis-cluster到redis-cluster的快速复制
