Information Schema SYSTEM_VARIABLES Table
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 mariadbd --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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