RDBMS Type: MySQL
SHOW [GLOBAL | SESSION] VARIABLES
[LIKE 'pattern' | WHERE expr]
SHOW VARIABLES shows the values of MySQL system variables (see
This statement does not require any privilege. It requires only the
ability to connect to the server.
System variable information is also available from these sources:
o Performance Schema tables. See
o The mysqladmin variables command. See
For SHOW VARIABLES, a LIKE clause, if present, indicates which variable
names to match. A WHERE clause can be given to select rows using more
general conditions, as discussed in
SHOW VARIABLES accepts an optional GLOBAL or SESSION variable scope
o With a GLOBAL modifier, the statement displays global system variable
values. These are the values used to initialize the corresponding
session variables for new connections to MySQL. If a variable has no
global value, no value is displayed.
o With a SESSION modifier, the statement displays the system variable
values that are in effect for the current connection. If a variable
has no session value, the global value is displayed. LOCAL is a
synonym for SESSION.
o If no modifier is present, the default is SESSION.
The scope for each system variable is listed at
SHOW VARIABLES is subject to a version-dependent display-width limit.
For variables with very long values that are not completely displayed,
use SELECT as a workaround. For example:
Most system variables can be set at server startup (read-only variables
such as version_comment are exceptions). Many can be changed at runtime
with the SET statement. See
and [HELP SET].
With a LIKE clause, the statement displays only rows for those
variables with names that match the pattern. To obtain the row for a
specific variable, use a LIKE clause as shown:
SHOW VARIABLES LIKE 'max_join_size';
SHOW SESSION VARIABLES LIKE 'max_join_size';
To get a list of variables whose name match a pattern, use the %
wildcard character in a LIKE clause:
SHOW VARIABLES LIKE '%size%';
SHOW GLOBAL VARIABLES LIKE '%size%';
Wildcard characters can be used in any position within the pattern to
be matched. Strictly speaking, because _ is a wildcard that matches any
single character, you should escape it as \_ to match it literally. In
practice, this is rarely necessary.