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. |
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/