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Mysql 笔记
2019-10-30T11:51:23+08:00
2019-10-30T11:51:23+08:00
MySQL 5.7 配置文件 my.cnf
[mysqld]
datadir = /db/mysql
socket = /var/lib/mysql/mysql.sock
symbolic-links = 0
log-timestamps = SYSTEM
slow-query-log = 1
slow-query-log-file = /var/log/mysqld/slow.log
long-query-time = 8
#log-queries-not-using-indexes = 1
log-error = /var/log/mysqld/error.log
pid-file = /var/run/mysqld/mysqld.pid
max-connections = 1000
max-connect-errors = 1000
max-user-connections = 600
interactive-timeout = 3600
wait-timeout = 3600
skip-name-resolve = 1
lower-case-table-names = 1
default-time-zone = '+08:00'
character-set-server = utf8mb4
sql-mode = NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
bind-address = 0.0.0.0
table-open-cache = 2048
default-storage-engine = innodb
innodb-autoinc-lock-mode = 2
innodb-flush-log-at-trx-commit = 0
# 建议物理内存一半
innodb-buffer-pool-size = 8G
innodb-buffer-pool-instances = 8
max-allowed-packet = 512M
query-cache-size = 0
query-cache-type = 0
# 建议点分 ip 的最后一个数字
server-id = 123
# bin log
#binlog-format = ROW
#log-bin = /var/lib/mysql/mysql-bin
#expire-logs-days = 3
# relay log
#read-only = 1
#replicate-wild-do-table = db1.%
#relay-log = /var/lib/mysql/mysql-relay-bin
#slave-parallel-type = logical-clock
复制表结构
create table db1 . t1 like db2 . t2 ;
create table db1 . t1 select db2 . t2 where 1 = 2 ;
复制表结构及其数据
create table db1 . t1 select db2 . t2 [ where ...]
复制表数据
insert into db2.t2(column1, column2 ...)
select column1, column2 ... from db1.t1 [where ...]
通过复制表文件来复制表数据
在db2中创建同结构表
create table db2 . t1 like db1 . t1 ;
丢弃表空间
alter table db2 . t1 discard tablespace ;
复制 t1 的表数据文件
#关闭数据库
systemctl stop mysqld
cd /var/lib/mysql
scp db1/t1.idb db2/t1.idb
chown mysql.mysql db2/t1.idb
#启动数据库
systemctl start mysqld
导入表空间
alter table db2 . t1 import tablespace ;
设置一个表的空列自增
-- 删除可能存在的主键
alter table 表名 drop primary key ;
alter table 表名 modify 列名 auto_increment primary key ;
查看数据库中每个表的全部列名
select table_name , column_name from
information_schema . columns
where table_schema = '数据库名' ;
查看数据库中每个表的行数
select table_name , table_rows
from information_schema . tables
where table_schema = '数据库名' ;
查看数据库中每个表的索引
select table_name , column_name , index_name
from INFORMATION_SCHEMA . STATISTICS
where table_schema = '数据库名' ;
表的部分列数据到另一个表
update db2 . t2 ( column1 , column2 ...) = (
select column1 , column2 from db1 . t1
where db1 . t1 . id = db2 . t2 . id );
把语句执行结果写到文件
mysql -uroot -p -hsever_ip -Ddb_name
-Ne "select ... from table_name;" > file_name
表分区
查看表的分区情况
select table_schema , table_name , partition_name , table_rows
from information_schema . partitions
where table_name = 'table_name' ;
建表时指定
create table table_name (...)
partition by range columns ( column_name )
( partition part_name values less than ( some_value ));
修改成分区表
alter table table_name
partition by range ( column_name )
( partition part_name values less than ( som_value ));
增加分区
alter table table_name add partition
( partition part_name values less than ( som_value ));
删除分区
alter table table_name drop partition part_name ;
合并/拆分分区
alter table table_name
reorganize part_old_1 , part_old_2 , part_old_3 into
( partition part_new_1 values less than ( value_1 ),
partition part_new_2 values less than ( value_2 ));
重建分区，整理分区碎片
alter table table_name
rebuild partition part_name_1 , part_name_2 ;
优化分区，回收空间，整理碎片
alter table table_name
optimize partition part_name_1 , part_name_2 ;
分析分区，读取并保存分区的健分布
alter table table_name
analyze partition part_name_1 , part_name_2 ;
修复分区
alter table table_name
repair partition part_name_1 , part_name_2 ;
检查分区
alter table table_name
check partition part_name_1 , part_name_2 ;
MySQL 5.7 从库多线程同步
stop slave ;
set global slave_parallel_type = 'logical_clock' ;
set global slave_parallel_workers = 4 ;
start slave ;
show processlist ;
MySQL 5.7 提示密码复杂度不够
set global validate_password_policy = 0 ;
MySQL 5.7 从库复制失败跳过指定数量的事务
stop slave ;
-- 跳过一个事务
SET GLOBAL SQL_SLAVE_SKIP_COUNTER = 1 ;
start slave ;
-- 修改 my.cnf
slave - skip - errors = 1062 , 1053 , 1146 , 1032 # 跳过指定 error no类型的错误
slave - skip - errors = all # 跳过所有错误
MySQL 5.7 查看全部任务
-- 分号换成 \G 显示完整 sql
show processlist ;
show full processlist ;
SELECT command FROM information_schema . processlist ;
MySQL 5.7 ssl 连接
--ssl-mode=REQUIRED
MariaDB 10.1 修改密码
UPDATE user SET password = password ( 'newpassword' ) WHERE user = 'root' ;
MySQL 5.7 编码
查看
SHOW VARIABLES LIKE 'character_set%' ;
数据库连接参数中， ，
更改数据库编码
ALTER DATABASE db_name
CHARSET UTF8MB4 COLLATE UTF8MB4_GENERAL_CI ;
更改表编码
ALTER TABLE table_name
CONVERT TO CHARSET UTF8MB4 COLLATE UTF8MB4_GENERAL_CI ;
MySQL 5.7 升级数据库管理表结构
mysql_upgrade -u root -p
MySQL 5.7 误删 root 后恢复 root 账户
停止 mysql 服务
systemctl stop mysqld
修改 my.cnf
# 添加如下一行
skip-grant-tables
启动 mysql 服务
systemctl start mysqld
重建 root 账户，并授权
insert into user
set user = 'root' ,
ssl_cipher = '' ,
x509_issuer = '' ,
x509_subject = '' ;
update user
set Host = 'localhost' ,
select_priv = 'y' ,
insert_priv = 'y' ,
update_priv = 'y' ,
Alter_priv = 'y' ,
delete_priv = 'y' ,
create_priv = 'y' ,
drop_priv = 'y' ,
reload_priv = 'y' ,
shutdown_priv = 'y' ,
Process_priv = 'y' ,
file_priv = 'y' ,
grant_priv = 'y' ,
References_priv = 'y' ,
index_priv = 'y' ,
create_user_priv = 'y' ,
show_db_priv = 'y' ,
super_priv = 'y' ,
create_tmp_table_priv = 'y' ,
Lock_tables_priv = 'y' ,
execute_priv = 'y' ,
repl_slave_priv = 'y' ,
repl_client_priv = 'y' ,
create_view_priv = 'y' ,
show_view_priv = 'y' ,
create_routine_priv = 'y' ,
alter_routine_priv = 'y' ,
create_user_priv = 'y' ,
event_priv = 'y' ,
trigger_priv = 'y' ,
create_tablespace_priv = 'y'
where user = 'root' ;
flush privileges ;
停止 mysql 服务
systemctl stop mysqld
修改 my.cnf
# 删除刚添加的如下一行
#skip-grant-tables
启动 mysql 服务， systemctl start mysqld
通过EXPLAIN分析SQL的执行计划
使用
explain sql
select_type 查询类型
SIMPLE 简单表，没有表连接或子查询
PRIMARY 最外层的查询
UNION union语句的后置查询
SUBQUERY 第一个子查询
table 表/别名
type 访问类型
ALL 全表扫描
index 全索引扫描
range 索引范围扫描
ref 非唯一索引扫描
eq_ref 唯一索引扫描
const,system 单表最多一个匹配行
NULL 不需要扫描表或索引
possible_keys 查询可能使用的索引
key 实际使用的索引
key_len 使用的索引字段的长度
ref 其他匹配字段
rows 扫描行的数量
filtered 满足查询条件的记录占存储引擎返回记录的比例
Extra 执行情况说明
Using Index 全部使用索引，没有回表查询
Using Where 有回表查询
Using Index Condition ICP优化，
Using Flesort 依靠索引顺序达不到排序效果，需额外排序
统计 insert、delete、update 和 select 次数
show global status where Variable_name in
( 'com_insert' , 'com_delete' , 'com_update' , 'com_select' );
csv 文件
导出
# Shell 终端
# mysql -e "select * from t1
into outfile '/var/lib/mysql-files/t1.csv'
fields terminated by ','
enclosed by '\"'
escaped by '\\\'
lines terminated by '\n'"
# MySQL 终端
# MySQL> select * from t1
into outfile '/var/lib/mysql-files/t1.csv'
fields terminated by ','
enclosed by '\"'
escaped by '\\'
lines terminated by '\n';
导入
# Shell 终端
# mysql -e "load data infile '/var/lib/mysql-files/t1.csv'
into table t1
fields terminated by ','
enclosed by '\"'
escaped by '\\\'
lines terminated by '\n'"
# MySQL 终端
# MySQL> load data infile '/var/lib/mysql-files/t1.csv'
into table t1
fields terminated by ','
enclosed by '\"'
escaped by '\\'
lines terminated by '\n';
