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如何避免MySQL全表的误删除/更新操作
MySQL [sbtest]> show variables like 'sql_safe_updates';+------------------+-------+| Variable_name | Value |+------------------+-------+| sql_safe_updates | OFF |+------------------+-------+1 row in set (0.002 sec)MySQL [sbtest]> set session sql_safe_updates=1;Query OK, 0 rows affected (0.000 sec)MySQL [sbtest]> show variables like 'sql_safe_updates';+------------------+-------+...
MySQL 如何整理表空间碎片
mysql> show table status like 'sbtest4'\G*************************** 1. row *************************** Name: sbtest4 Engine: InnoDB Version: 10 Row_format: Dynamic Rows: 826772 Avg_row_length: 1850 Data_length: 1529921536Max_data_length: 0 Index_length: 0 Data_free: 14680064 Auto_increment: 10850668 Create_time: 2022-03-15 15:28:30...
MySQL 如何整理表空间碎片
mysql> show table status like 'sbtest4'\G*************************** 1. row *************************** Name: sbtest4 Engine: InnoDB Version: 10 Row_format: Dynamic Rows: 826772 Avg_row_length: 1850 Data_length: 1529921536Max_data_length: 0 Index_length: 0 Data_free: 14680064 Auto_increment: 10850668 Create_time: 2022-03-15 15:28:30...
MySQL 2038 问题分析
mysql> select version();+------------+| version() |+------------+| 5.7.19-log |+------------+1 row in set (0.00 sec)mysql> select now();+---------------------+| now() |+---------------------+| 2022-10-10 00:00:42 | +---------------------+1 row in set (0.00 sec)mysql> insert into student_score select * from student_score limit 1;Query OK, 1 row affected (0.00 sec)...
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如何合理配置MySQL Slow Query Log
# 问题描述如何正确配置 MySQL 的 slow query log?# 常见参数说明## 1.min_examined_row_limit测试配置文件如下````undefined###slow_loglong_query_time=1 //条件1:时间需要大于1sslow_query_log=1slow_query_log_file=/data/3306/data/slow.logmin_examined_row_limit=2000 //条件2:检查扫描的行数>2000log_queries_not_using_indexes=1 ````需要同时满足条件1和条件2才会被记录到slow.log中...
如何合理配置MySQL Slow Query Log
# 问题描述如何正确配置 MySQL 的 slow query log?# 常见参数说明## 1.min_examined_row_limit测试配置文件如下```###slow_loglong_query_time=1 //条件1:时间需要大于1sslow_query_log=1slow_query_log_file=/data/3306/data/slow.logmin_examined_row_limit=2000 //条件2:检查扫描的行数>2000log_queries_not_using_indexes=1 ```需要同时满足条件1和条件2才会被记录到slow.log中,利用...
MySQL 统计信息相关参数解析
mysql> alter table test0407 STATS_PERSISTENT=0;Query OK, 0 rows affected (0.04 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> show create table test0407;+----------+------------------------------| Table | Create Table |+----------+-----------------------------| test0407 | CREATE TABLE `test0407` ( `id` int(11) DEFAULT NULL) ENGINE=InnoDB DEFAULT CHARSET=utf8 ST...
如何解决 MySQL 主从切换后自增列数值不一致问题?
mysql> drop test_autoinc;ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'test_autoinc' at line 1mysql> drop table test_autoinc;Query OK, 0 rows affected (0.01 sec)mysql> Create table test_autoinc(id int auto_increment, c1 int,c2 varchar(100),primary key(id),unique key(c1));Query OK, ...
如何排查MySQL中MDL锁等待
# 问题描述使用 show full processlist 查看当前数据库正在运行的 SQL 语句,我们可能会发现 State 列为 **Waiting for table metadata lock**,我们该如何排查此类问题?# 问题复现1. 在会话 1 中显式开启一个事务,执行一个 update 操作,不进行提交````undefinedmysql> begin;Query OK, 0 rows affected (0.00 sec)mysql> update t1 set name='liwangz' where id=1;Query OK, 1 row affected (0.00 sec)Rows matched:...
可修改参数列表(MySQL 5.7)
本文介绍云数据库 MySQL 版为数据库版本 MySQL 5.7 提供的可修改参数,以及参数的默认值、修改后是否需要重启和取值范围。 序号 参数名 参数默认值 是否需要重启 取值范围 1 auto_increment_increment 1 否 [1-6553... 10 binlog_rows_query_log_events OFF 否 [ONOFF] 11 binlog_stmt_cache_size 32768 否 [4096-16777216] 12 block_encryption_mode aes-128-ecb 否 [aes-128-ecbaes-192-ecbaes-256-ecbaes-128-cbcaes-192-cbcaes...
可修改参数列表(MySQL 8.0)
本文介绍云数据库 MySQL 版为数据库版本 MySQL 8.0 提供的可修改参数,以及参数的默认值、修改后是否需要重启和取值范围。 序号 参数名 参数默认值 是否需要重启 取值范围 1 auto_increment_increment 1 否 [1-6553... 10 binlog_rows_query_log_events OFF 否 [ONOFF] 11 binlog_stmt_cache_size 32768 否 [4096-16777216] 12 block_encryption_mode aes-128-ecb 否 [aes-128-ecbaes-192-ecbaes-256-ecbaes-128-cbcaes-192-cbcaes...
RDS for MySQL handler 相关指标说明
从MySQL 官方文档描述如下:The number of requests to read the next row in the data file[1]。```sqlmysql> show global status like '%Handler_read_rnd_next%';+-----------------------+----------+| Variable_name | Value |+-----------------------+----------+| Handler_read_rnd_next | 42264759 |+-----------------------+----------+1 row in set (0.00 sec)```**注**:如果正进行大量的表扫...
RDS for MySQL handler 相关指标说明
从MySQL 官方文档描述如下:The number of requests to read the next row in the data file[1]。```sqlmysql> show global status like '%Handler_read_rnd_next%';+-----------------------+----------+| Variable_name | Value |+-----------------------+----------+| Handler_read_rnd_next | 42264759 |+-----------------------+----------+1 row in set (0.00 sec)```**注**:如果正进行大量的表扫描...
