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mysql用户和权限管理
库和表级别：TABLE or DATABASE
ALTER
CREATE
CREATE VIEW
DROP
INDEX
SHOW VIEW
GRANT OPTION：能够把自己获得的权限赠经其他用户一个副本；
数据操作：
SELECT
INSERT
DELETE
UPDATE
字段级别：
SELECT(col1,col2,...)
UPDATE(col1,col2,...)
INSERT(col1,col2,...)
所有有限：ALL PRIVILEGES, ALL
元数据数据库：mysql.
授权表：
db, host, user
columns_priv, tables_priv, procs_priv, proxies_priv
-------------------------------------------------------------------------------------------
用户账号：
‘USERNAME‘@‘HOST‘：
@‘HOST‘:主机名；
IP地址或Network;
通配符：%, _: 172.16.%.%
---------------------------------------------------------------------------------------
创建用户：CREATE USER ‘USERNAME‘@‘HOST‘ [IDENTIFIED BY ‘password‘]；
查看用户获得的授权：SHOW GRANTS FOR ‘USERNAME‘@‘HOST‘
用户重命名：RENAME USER old_user_name TO new_user_name
删除用户：DROP USER ‘USERNAME‘@‘HOST‘
-------------------------------------------------------------------------------------------
修改密码：
(1) SET PASSWORD FOR ""@"" password(‘your_password‘)
(2) UPDATE mysql.user SET password=PASSWORD(‘your_password‘) WHERE user="" and host="";
flush privileges;
(3) mysqladmin password your_password
mysqladmin [OPTIONS] command command....
-u, -h, -p
忘记管理员密码的解决办法：
(1) 启动mysqld进程时，为其使用：--skip-grant-tables(用户不被验证登陆) --skip-networking（禁止远程）
(2) 使用UPDATE命令修改管理员密码
(3) 关闭mysqld进程，移除上述两个选项，重启mysqld;
密码修改
[[email protected] ~]# mysqladmin password redhat
[[email protected] ~]# mysql -p
Enter password:
ERROR 1045 (28000): Access denied for user ‘root‘@‘localhost‘ (using password: YES)
[[email protected] ~]# vim /etc/rc.d/init.d/mysqld
case "$mode" in
‘start‘)
# Start daemon
# Safeguard (relative paths, core dumps..)
cd $basedir
echo $echo_n "Starting MySQL"
if test -x $bindir/mysqld_safe
then
# Give extra arguments to mysqld with the my.cnf file. This script
# may be overwritten at next upgrade.
$bindir/mysqld_safe --skip-grant-tables --skip-networking --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null 2>&1 &
[[email protected] ~]# vim /etc/rc.d/init.d/mysqld
[[email protected] ~]# service mysqld restart
Shutting down MySQL.. [确定]
Starting MySQL.. [确定]
[[email protected] ~]# mysql
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 4
Server version: 10.0.13-MariaDB-log Source distribution
Copyright (c) 2000, 2014, Oracle, SkySQL Ab and others.
Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.
MariaDB [(none)]> update mysql.user set password=password("aaa") where user=‘root‘ and host=‘localhost‘;
Query OK, 1 row affected (0.04 sec)
Rows matched: 1 Changed: 1 Warnings: 0
MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> quit
Bye
[[email protected] ~]# mysql -p aaa
Enter password:
ERROR 1049 (42000): Unknown database ‘aaa‘
[[email protected] ~]# mysql -paaa
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 6
Server version: 10.0.13-MariaDB-log Source distribution
Copyright (c) 2000, 2014, Oracle, SkySQL Ab and others.
Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.
MariaDB [(none)]>
[[email protected] ~]# vim /etc/rc.d/init.d/mysqld
case "$mode" in
‘start‘)
# Start daemon
# Safeguard (relative paths, core dumps..)
cd $basedir
echo $echo_n "Starting MySQL"
if test -x $bindir/mysqld_safe
then
# Give extra arguments to mysqld with the my.cnf file. This script
# may be overwritten at next upgrade. $bindir/mysqld_safe --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null 2>&1 &
wait_for_ready; return_value=$?
[[email protected] ~]# service mysqld restart
Shutting down MySQL.. [确定]
Starting MySQL.. [确定]
----------------------------------------------------------------------------------
授权：GRANT
GRANT priv_type[,...] ON [{table|function|procedure}] db.{table|routine} TO ‘USERNAME‘@‘HOST‘ [IDENTIFIED BY ‘password‘]
[REQUIRE SSL] [WITH with_option]
with_option:
GRANT OPTION
| MAX_QUERIES_PER_HOUR count
| MAX_UPDATES_PER_HOUR count
| MAX_CONNECTIONS_PER_HOUR count
| MAX_USER_CONNECTIONS count
取消授权：REVOKE
REVOKE priv_type [(column_list)] [, priv_type [(column_list)]] ... ON [object_type] priv_level FROM user [, user] ...
------------------------------------------------------------------------------
查询缓存：
快速查询，跳过解析，分析。
注意：更新多缓存没意义。
查询语句任何字符上的不同，都会导致缓存不能命中；
哪此查询可能不会被缓存？
查询中包含UDF、存储函数、用户自定义变量、临时表、mysql库中系统表、或者包含列级权限的表、有着不确定值的函数(Now());
查询缓存相关的服务器变量：
注意：修改以下参数，全部缓存重新开始。
MariaDB [(none)]> show global variables like ‘query%‘;
+------------------------------+----------+
| Variable_name | Value |
+------------------------------+----------+
| query_alloc_block_size | 8192 |
| query_cache_limit | 1048576 |
| query_cache_min_res_unit | 4096 |
| query_cache_size | 16777216 |
| query_cache_strip_comments | OFF |
| query_cache_type | ON |
| query_cache_wlock_invalidate | OFF |
| query_prealloc_size | 8192 |
+------------------------------+----------+
8 rows in set (0.00 sec)
query_cache_min_res_unit: 查询缓存中内存块的最小分配单位；
较小值会减少浪费，但会导致更频繁的内存分配操作；
较大值会带来浪费，会导致碎片过多；
查询的平均大小：查询做大值+查询最小值/查询次数
query_cache_limit：能够缓存的最大查询结果；
对于有着较大结果的查询语句，建议在SELECT中使用SQL_NO_CACHE
query_cache_size：查询缓存总共可用的内存空间；单位是字节，必须是1024的整数倍；
query_cache_type: ON, OFF, DEMAND（在SELECT中使用SQL_CACHE）
query_cache_wlock_invalidate：如果某表被其它的连接锁定，是否仍然可以从查询缓存中返回结果；默认值为OFF，表示可以在表被其它连接淘宝的场景中继续从缓存返回数据；ON则表示不允许；
查询相关的状态变量
SHOW GLOBAL STATUS LIKE ‘Qcache%‘;
+-------------------------+----------+
| Variable_name | Value |
+-------------------------+----------+
| Qcache_free_blocks 空闲内存块 | 1 |
| Qcache_free_memory | 16759688 |
| Qcache_hits | 0 |
| Qcache_inserts 可缓存语句的次数 | 0 |
| Qcache_lowmem_prunes 查询缓存内存太小，清理缓存次数 | 0 |
| Qcache_not_cached 可缓存没有缓存 | 0 |
| Qcache_queries_in_cache 缓存空间缓存下来的个数| 0 |
| Qcache_total_blocks | 1 |
+-------------------------+----------+
缓存命中率的评估：Qcache_hits/(Qcache_hits+Com_select)
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