MySQL插件（一）介绍
插件
-
-
- 简介
- 插件类型
- 加载和卸载插件
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简介
在第一节中提到，MySQL 是支持动态可插拔的储存引擎体系架构。
而储存引擎其实也是一种插件类型，所以在继续储存引擎的后续介绍之前，有必要先来了解一下MySQL的插件。
可以从INFORMATION_SCHEMA.PLUGINS 或者 SHOW PLUGINS 可以获取到当前 MySQL 内部所有插件的详情。
mysql> mysql> select * from information_schema.plugins;
+----------------------------+----------------+---------------+--------------------+---------------------+----------------+------------------------+--------------------------------------------+---------------------------------------------------------------------------+----------------+-------------+
| PLUGIN_NAME | PLUGIN_VERSION | PLUGIN_STATUS | PLUGIN_TYPE | PLUGIN_TYPE_VERSION | PLUGIN_LIBRARY | PLUGIN_LIBRARY_VERSION | PLUGIN_AUTHOR | PLUGIN_DESCRIPTION | PLUGIN_LICENSE | LOAD_OPTION |
+----------------------------+----------------+---------------+--------------------+---------------------+----------------+------------------------+--------------------------------------------+---------------------------------------------------------------------------+----------------+-------------+
| binlog | 1.0 | ACTIVE | STORAGE ENGINE | 50725.0 | NULL | NULL | MySQL AB | This is a pseudo storage engine to represent the binlog in a transaction | GPL | FORCE |
| mysql_native_password | 1.1 | ACTIVE | AUTHENTICATION | 1.1 | NULL | NULL | R.J.Silk, Sergei Golubchik | Native MySQL authentication | GPL | FORCE |
| sha256_password | 1.1 | ACTIVE | AUTHENTICATION | 1.1 | NULL | NULL | Oracle | SHA256 password authentication | GPL | FORCE |
| CSV | 1.0 | ACTIVE | STORAGE ENGINE | 50725.0 | NULL | NULL | Brian Aker, MySQL AB | CSV storage engine | GPL | FORCE |
| MEMORY | 1.0 | ACTIVE | STORAGE ENGINE | 50725.0 | NULL | NULL | MySQL AB | Hash based, stored in memory, useful for temporary tables | GPL | FORCE |
| InnoDB | 5.7 | ACTIVE | STORAGE ENGINE | 50725.0 | NULL | NULL | Oracle Corporation | Supports transactions, row-level locking, and foreign keys | GPL | FORCE |
| INNODB_TRX | 5.7 | ACTIVE | INFORMATION SCHEMA | 50725.0 | NULL | NULL | Oracle Corporation | InnoDB transactions | GPL | FORCE |
| INNODB_LOCKS | 5.7 | ACTIVE | INFORMATION SCHEMA | 50725.0 | NULL | NULL | Oracle Corporation | InnoDB conflicting locks | GPL | FORCE |
| INNODB_LOCK_WAITS | 5.7 | ACTIVE | INFORMATION SCHEMA | 50725.0 | NULL | NULL | Oracle Corporation | InnoDB which lock is blocking which | GPL | FORCE |
......
| INNODB_SYS_VIRTUAL | 5.7 | ACTIVE | INFORMATION SCHEMA | 50725.0 | NULL | NULL | Oracle Corporation | InnoDB SYS_VIRTUAL | GPL | FORCE |
| MyISAM | 1.0 | ACTIVE | STORAGE ENGINE | 50725.0 | NULL | NULL | MySQL AB | MyISAM storage engine | GPL | FORCE |
| MRG_MYISAM | 1.0 | ACTIVE | STORAGE ENGINE | 50725.0 | NULL | NULL | MySQL AB | Collection of identical MyISAM tables | GPL | FORCE |
| PERFORMANCE_SCHEMA | 0.1 | ACTIVE | STORAGE ENGINE | 50725.0 | NULL | NULL | Marc Alff, Oracle | Performance Schema | GPL | FORCE |
| ARCHIVE | 3.0 | ACTIVE | STORAGE ENGINE | 50725.0 | NULL | NULL | Brian Aker, MySQL AB | Archive storage engine | GPL | ON |
| BLACKHOLE | 1.0 | ACTIVE | STORAGE ENGINE | 50725.0 | NULL | NULL | MySQL AB | /dev/null storage engine (anything you write to it disappears) | GPL | ON |
| FEDERATED | 1.0 | DISABLED | STORAGE ENGINE | 50725.0 | NULL | NULL | Patrick Galbraith and Brian Aker, MySQL AB | Federated MySQL storage engine | GPL | OFF |
| partition | 1.0 | ACTIVE | STORAGE ENGINE | 50725.0 | NULL | NULL | Mikael Ronstrom, MySQL AB | Partition Storage Engine Helper | GPL | ON |
| ngram | 0.1 | ACTIVE | FTPARSER | 1.1 | NULL | NULL | Oracle Corp | Ngram Full-Text Parser | GPL | ON |
+----------------------------+----------------+---------------+--------------------+---------------------+----------------+------------------------+--------------------------------------------+---------------------------------------------------------------------------+----------------+-------------+
插件类型
在 MySQL 5.7.25 中，主要有以下几种类型：
- 储存引擎（storage engines）
- 全文索引解析插件（Full-text parsers）
- 守护插件（Daemons）
- INFORMATION_SCHEMA 插件（INFORMATION_SCHEMA tables）
- 日志同步插件（Semisynchronous replication）
- 认证插件（Authentication）
- 密码验证插件（Password validation and strength checking）
- 密钥环插件（Keyring）
源码中 include/mysql/plugin.h 有各种插件类型的宏定义：
/*
The allowable types of plugins
*/
#define MYSQL_UDF_PLUGIN 0 /* User-defined function */
#define MYSQL_STORAGE_ENGINE_PLUGIN 1 /* Storage Engine */
#define MYSQL_FTPARSER_PLUGIN 2 /* Full-text parser plugin */
#define MYSQL_DAEMON_PLUGIN 3 /* The daemon/raw plugin type */
#define MYSQL_INFORMATION_SCHEMA_PLUGIN 4 /* The I_S plugin type */
#define MYSQL_AUDIT_PLUGIN 5 /* The Audit plugin type */
#define MYSQL_REPLICATION_PLUGIN 6 /* The replication plugin type */
#define MYSQL_AUTHENTICATION_PLUGIN 7 /* The authentication plugin type */
#define MYSQL_VALIDATE_PASSWORD_PLUGIN 8 /* validate password plugin type */
#define MYSQL_GROUP_REPLICATION_PLUGIN 9 /* The Group Replication plugin */
#define MYSQL_KEYRING_PLUGIN 10 /* The Keyring plugin type */
#define MYSQL_MAX_PLUGIN_TYPE_NUM 11 /* The number of plugin types */
如果需要实现自定义的储存引擎，需要自定义一个类型为#define MYSQL_STORAGE_ENGINE_PLUGIN 1的插件类型。
加载和卸载插件
在源码编译时，MySQL 插件可以直接以 buildin 的方式作为静态插件内嵌到 mysqld 中，从而在 mysqld 服务起来之后，自动加载插件。
此外，在编译时，插件也可以编译为动态插件，从而在在运行时可以加载和卸载插件，做到可插拔。
动态插件可以在服务器启动时通过指定 option 加载，也可以在运行时加载和卸载插件。
- 启动时加载
指定plugin_load选项并指定特定的插件名称和对应动态插件库。
也可以写入到 my.cnf 配置项中support-files/mysql.server restart --plugin_load=example=ha_example.so[mysqld] plugin-load=example=ha_example.soTips:
一般源码编译的会有ha_example.so动态查看库，这是一个储存引擎实例插件，位于plugin_dir路径中，plugin_dir一般位于安装目录下的lib/plugin中，也可以通过查询得到：mysql> select @@plugin_dir; +-------------------------------------+ | @@plugin_dir | +-------------------------------------+ | /opt/mysql-5.7.25/mysql/lib/plugin/ | +-------------------------------------+ 1 row in set (0.01 sec)可以去路径下查看都有哪些动态插件
root@ivan:/opt/mysql-5.7.25/mysql/lib/plugin# ls adt_null.so keyring_file.so libtest_session_in_thd.so libtest_sql_processlist.so locking_service.so rewrite_example.so auth.so keyring_udf.so libtest_sql_2_sessions.so libtest_sql_replication.so mypluglib.so rewriter.so auth_socket.so libdaemon_example.so libtest_sql_all_col_types.so libtest_sql_shutdown.so mysql_no_login.so semisync_master.so auth_test_plugin.so libtest_framework.so libtest_sql_cmds_1.so libtest_sql_sqlmode.so mysqlx.so semisync_slave.so connection_control.so libtest_services.so libtest_sql_commit.so libtest_sql_stored_procedures_functions.so qa_auth_client.so test_security_context.so daemon_example.ini libtest_services_threaded.so libtest_sql_complex.so libtest_sql_views_triggers.so qa_auth_interface.so test_udf_services.so group_replication.so libtest_session_detach.so libtest_sql_errors.so libtest_x_sessions_deinit.so qa_auth_server.so validate_password.so ha_example.so libtest_session_info.so libtest_sql_lock.so libtest_x_sessions_init.so replication_observers_example_plugin.so version_token.so root@ivan:/opt/mysql-5.7.25/mysql/lib/plugin# - 运行时动态加载
mysql> install plugin example soname 'ha_example.so'; Query OK, 0 rows affected (0.01 sec) mysql> show plugins; +----------------------------+----------+--------------------+---------------+---------+ | Name | Status | Type | Library | License | +----------------------------+----------+--------------------+---------------+---------+ | MEMORY | ACTIVE | STORAGE ENGINE | NULL | GPL | | InnoDB | ACTIVE | STORAGE ENGINE | NULL | GPL | ...... | partition | ACTIVE | STORAGE ENGINE | NULL | GPL | | ngram | ACTIVE | FTPARSER | NULL | GPL | | EXAMPLE | ACTIVE | STORAGE ENGINE | ha_example.so | GPL | +----------------------------+----------+--------------------+---------------+---------+ - 卸载插件
mysql> uninstall plugin example; Query OK, 0 rows affected (0.01 sec)
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