4 rows in set (0.00 sec) mysql> truncate t12; Query OK, 0 rows affected (0.16 sec) mysql> insert into t12(name) values('Jack'),('Tom'),('Mark'),('Black'); Query OK, 4 rows affected (0.01 sec) Records: 4 Duplicates: 0 Warnings: 0 mysql> select * from t12; +---+---+ ...
--需要归档的数据量mysql admin@192.168.58.3:employees>selectcount(*)fromemployeeswherefirst_name='Anneke';+---+|count(*)|+---+|225|+---+1rowinsetTime:0.025s--执行归档操作# pt-archiver--source h=192.168.58.3,P=3306,u=admin,D=employees,t=employees,A=utf8 --dest h=192.168.58.3,P=3...
(这里kevin库下就2张表,如果是N张表,就执行复制->粘贴执行) | drop table heihei; | +---+ 2 rows in set (0.00 sec) mysql> use kevin; #切换到kevin库下,然后执行将上面复制的drop语句,直接粘贴执行即可! Database changed mysql> drop table haha; Query OK, 0 rows affected (0.09 sec) mysql>...
The speed of delete operations may also be affected by factors discussed inSection 8.2.4.3, “Optimizing DELETE Statements”. To ensure that a givenDELETEstatement does not take too much time, the MySQL-specificLIMITrow_countclause forDELETEspecifies the maximum number of rows to be deleted. If...
UPDATE pay_stream a SET a.return_amount = 0 WHERE a.pay_id IN (SELECT b.pay_id FROM pay_main b WHERE b.user_name = '1388888888'); id select_type table partitions type possible_keys key key_len ref rows filtered Extra --- --- --- --- --- --- --- --- --- --- --...
最近,在脉脉上看到一个楼主提出的问题:MySQL数据量大时,delete操作无法命中索引;并且还附上了相关案例截图。 最终,楼主通过开启MySQL分析优化器追踪,定位到是优化器搞的鬼,它觉得花费时间太长。因为我这个是测试数据,究其原因是因为数据倾斜,导致计算出的数据占比较大、花费时间长。
delete from tu where id in (3,4); Query OK, 2 rows affected (0.00 sec) ---TRANSACTION 146880, ACTIVE 1 sec 2 lock struct(s), heap size 360, 2 row lock(s), undo log entries 2 MySQL thread id 1, OS thread handle 0x7f61ab1c7700, query id 928 localhost msandbox cleaning up ...
MySQL中的DELETE语句用于删除表中的数据。当涉及到关联删除时,通常是指在一个表中删除记录的同时,也需要删除与之相关联的其他表中的记录。这通常通过外键约束和级联删除来实现。 优势 数据一致性:确保删除操作不会导致孤立的数据记录,保持数据库的完整性。 简化操作:通过一次操作即可删除多个表中的相关数据,减少手动...
in set (0.01 sec) #重置状态变量计数 mysql> flush status; Query OK, 0 rows affected (0.01 sec) mysql> select id, age ,phone from user where name like 'lyn12%'; Empty set (0.05 sec) mysql> explain select id, age ,phone from user where name like 'lyn12%'; +---+---+---+-...
TRANSACTION 272174, ACTIVE 0 sec fetching rows mysql tables in use 1, locked 1 LOCK WAIT 18 lock struct(s), heap size 1136, 58 row lock(s), undo log entries 41 MySQL thread id 298, OS thread handle 140425685493504, query id 5479767 172.18.70.114 root updating ...