Information Schema SYSTEM_VARIABLES Table

MariaDB starting with 10.1.1

The information_schema.SYSTEM_VARIABLES table was introduced in MariaDB 10.1.1

The Information Schema SYSTEM_VARIABLES table shows current values and various metadata of all system variables.

It contains the following columns:

Column	Description
`VARIABLE_NAME`	System variable name.
`SESSION_VALUE`	Session value of the variable or NULL if the variable only has a global scope.
`GLOBAL_VALUE`	Global value of the variable or NULL if the variable only has a session scope.
`GLOBAL_VALUE_ORIGIN`	How the global value was set — a compile-time default, auto-configured by the server, configuration file (or a command line), with the SQL statement.
`DEFAULT_VALUE`	Compile-time default value of the variable.
`VARIABLE_SCOPE`	Global, session, or session-only.
`VARIABLE_TYPE`	Data type of the variable value.
`VARIABLE_COMMENT`	Help text, usually shown in `mysqld --help --verbose`.
`NUMERIC_MIN_VALUE`	For numeric variables — minimal allowed value.
`NUMERIC_MAX_VALUE`	For numeric variables — maximal allowed value.
`NUMERIC_BLOCK_SIZE`	For numeric variables — a valid value must be a multiple of the "block size".
`ENUM_VALUE_LIST`	For `ENUM`, `SET`, and `FLAGSET` variables — the list of recognized values.
`READ_ONLY`	Whether a variable can be set with the SQL statement. Note that many "read only" variables can still be set on the command line.
`COMMAND_LINE_ARGUMENT`	Whether an argument is required when setting the variable on the command line. `NULL` when a variable can not be set on the command line.
`GLOBAL_VALUE_PATH`	Which config file the variable got its value from. `NULL` if not set in any config file. Added in MariaDB 10.5.0.

Example

SELECT * FROM information_schema.SYSTEM_VARIABLES 
  WHERE VARIABLE_NAME='JOIN_BUFFER_SIZE'\G
*************************** 1. row *****************************
        VARIABLE_NAME: JOIN_BUFFER_SIZE
        SESSION_VALUE: 131072
         GLOBAL_VALUE: 131072
  GLOBAL_VALUE_ORIGIN: COMPILE-TIME
        DEFAULT_VALUE: 131072
       VARIABLE_SCOPE: SESSION
        VARIABLE_TYPE: BIGINT UNSIGNED
     VARIABLE_COMMENT: The size of the buffer that is used for joins
    NUMERIC_MIN_VALUE: 128
    NUMERIC_MAX_VALUE: 18446744073709551615
   NUMERIC_BLOCK_SIZE: 128
      ENUM_VALUE_LIST: NULL
            READ_ONLY: NO
COMMAND_LINE_ARGUMENT: REQUIRED

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https://mariadb.com/kb/en/information-schema-system_variables-table/