ProxySQL

ProxySQL as a powerful middleware provides strong support for the MySQL architecture.

Currently well supported Master Slave \ MGR \ PXC, and provide connection pool, separate read and write, logging and other functions, of course, there are many other useful features, not list them here.

This article is based on the concept, from the basic official documents, officials have explained very clearly, I do not too much processed, summarized some useful to others.

installation

Installation is very simple ProxySQL

Connection ProxySQL

ProxySQL default management port 6032, the default 127.0.0.1 need to enter into the agreement and connection MySQL ways:

ProxySQL operating mechanism

RUNTIME

RUNTIME ProxySQL showing memory data structures used in processing the request thread.

runtime variables include:

1. The actual value of the Global variables

2. The list of back-end servers grouped into hostgroup in.

3. Let the MySQL User can connect proxysql

Note: runntime layer data, no one can directly edit, modify must be submitted by the next layer.

MEMORY

MEMORY (also sometimes referred to as main) memory is represented by the MySQL open database interface compatible. Users can connect to the MySQL client interface and access a variety of ProxySQL configuration table / database.

This interface is available for configuration table:

mysql_servers - the list of servers to connect to back-end ProxySQL

mysql_users - a list of users and their credentials to connect to the ProxySQL. Please note, ProxySQL will also use the same credentials to connect to back-end servers!

mysql_query_rules - list of rules will be evaluated when the query to a variety of back-end servers to route traffic. These rules can also rewrite the query result of the query cache can even be executed.

global_variables - list of global variables used by the proxy configuration can be adjusted during operation.

DISK 和 CONFIG FILE

DISK represent SQLite3 database on disk, the default location is $ (DATADIR) /proxysql.db. When you restart, the configuration is not retained in memory will be lost. Therefore, the configuration retained in DISK very important.

Boot process

If you find the database file (proxysql.db), ProxySQL from proxysql.db initialize its memory configuration. Therefore, the disk is loaded into the MEMORY, and then loaded into the RUNTIME.

If you can not find the database file (proxysql.db) and there is a configuration file (proxysql.cfg), then parses the configuration file and its content is loaded into memory database and then save it in proxysql.db and loaded into RUNTIME.

Be sure to note that if proxysql.db found, it will not parse the configuration file. In other words, during normal startup, ProxySQL only from persistent storage disk database to initialize its memory configuration.

There are four variables configuration file, even if there proxysql.db, always will be parsed from the configuration file to go:

1. datadir：

It defines the path of ProxySQL datadir, which stores database files, logs, and other files

2. restart_on_missing_heartbeats (What's New in 1.4.4):

If MySQL threads missed restart_on_missing_heartbeats heartbeat, then proxysql SIGABRT signal will trigger and restart. The default value is 10.

For details, see: https://github.com/sysown/proxysql/wiki/Watchdog .

3. execute_on_exit_failure（1.4.4中的新增内容）：

如果设置，ProxySQL父进程将在每次ProxySQL崩溃时执行定义的脚本。建议使用此设置生成警报或记录事件。

请注意，在崩溃的情况下，proxysql能够在几毫秒内重新启动，因此其他监视工具可能无法检测到正常故障。

4. errorlog（2.0.0中的新增内容）：

如果设置，ProxySQL将使用定义的文件作为错误日志。如果未传递此类变量，则errolog将位于datadir / proxysql.log中

初始化启动过程（或--initial）

在初始启动时，将从配置文件中填充内存和运行时配置。此后，配置将保留在ProxySQL的嵌入式SQLite数据库中。

通过使用--initial标志运行proxysql可以强制重新发生初始配置，这会将SQLite数据库文件重置为其原始状态（即配置文件中定义的状态）并重命名现有的SQLite数据库文件

如果需要回滚（如果需要，检查已定义的数据目录中的旧文件）。

重新加载启动（或--reload）

如果使用--reload标志执行proxysql，它会尝试将配置文件中的配置与数据库文件的内容合并。之后，ProxySQL将继续启动程序。

如果配置文件和数据库文件的参数存在冲突，则无法保证ProxySQL将成功管理合并，用户应始终验证合并结果是否符合预期。

核心配置表

在运行时修改配置是通过ProxySQL的MySQL管理端口（默认为6032）完成的。

连接到它后，您将看到一个与MySQL兼容的接口，用于查询各种与ProxySQL相关的表：

mysql> show tables;
+-------------------+
| tables            |
+-------------------+
| mysql_servers     |
| mysql_users       |
| mysql_query_rules |
| global_variables  |
| mysql_collations  |
| debug_levels      |
+-------------------+

每个这样的表都有明确的定义：

mysql_servers：包含要连接的ProxySQL的后端服务器列表

mysql_users：包含ProxySQL将用于向后端服务器进行身份验证的用户列表

mysql_query_rules: 包含用于缓存，路由或重写发送到ProxySQL的SQL查询的规则

global_variables: 包含在服务器初始配置期间定义的MySQL变量和管理变量

debug_levels: 仅用于调试ProxySQL的手动构建

在不同层级间移动配置信息

为了将配置持久化到磁盘或将配置加载到运行时，可以使用一组不同的管理命令，这些命令可以通过管理界面执行。

一旦理解了三层中的每一层的使用方式，语义都应该清楚。

连同每个命令的说明，每个命令旁边都有一个编号选项。该数字对应于下图中列出的箭头

要重新配置MySQL用户，请执行以下命令之一：

[1]   LOAD MYSQL USERS FROM MEMORY / LOAD MYSQL USERS TO RUNTIME

  将MySQL用户从MEMORY加载到RUNTIME数据结构，反之亦然

[2]   SAVE MYSQL USERS TO MEMORY / SAVE MYSQL USERS FROM RUNTIME

  将MySQL用户从RUNTIME保存到MEMORY

[3]   LOAD MYSQL USERS TO MEMORY / LOAD MYSQL USERS FROM DISK

  将持久化的MySQL用户从磁盘数据库加载到MEMORY

[4]   SAVE MYSQL USERS FROM MEMORY / SAVE MYSQL USERS TO DISK

  将MySQL用户从MEMORY中保存到DISK

[5]   LOAD MYSQL USERS FROM CONFIG

  从配置文件加载用户到MEMORY

常用的命令参考：

LOAD MYSQL USERS TO RUNTIME;
SAVE MYSQL USERS TO DISK;

LOAD MYSQL SERVERS TO RUNTIME;
SAVE MYSQL SERVERS TO DISK;

LOAD MYSQL QUERY RULES TO RUNTIME;
SAVE MYSQL QUERY RULES TO DISK;

LOAD MYSQL VARIABLES TO RUNTIME;
SAVE MYSQL VARIABLES TO DISK;

LOAD ADMIN VARIABLES TO RUNTIME;
SAVE ADMIN VARIABLES TO DISK;

注意：关键字MEMORY/RUNTIME 都支持缩写：
MEM for MEMORY
RUN for RUNTIME