Oracle 5.0 Reference Manual page 530

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.
For VARIABLES, if you specify neither
SHOW
The reason for requiring the
retrieving them is to prevent problems in the future. If we were to remove a
has the same name as a
change the
a
SESSION
variable might find only its own
GLOBAL
5.1.5.1. Structured System Variables
A structured variable differs from a regular system variable in two respects:
• Its value is a structure with components that specify server parameters considered to be closely
related.
• There might be several instances of a given type of structured variable. Each one has a different
name and refers to a different resource maintained by the server.
MySQL 5.0 supports one structured variable type, which specifies parameters governing the operation
of key caches. A key cache structured variable has these components:
•
key_buffer_size
•
key_cache_block_size
•
key_cache_division_limit
•
key_cache_age_threshold
This section describes the syntax for referring to structured variables. Key cache variables are used
for syntax examples, but specific details about how key caches operate are found elsewhere, in
Section 8.6.1, "The
To refer to a component of a structured variable instance, you can use a compound name in
instance_name.component_name
hot_cache.key_buffer_size
hot_cache.key_cache_block_size
cold_cache.key_cache_block_size
For each structured system variable, an instance with the name of
you refer to a component of a structured variable without any instance name, the
is used. Thus,
system variable.
Structured variable instances and components follow these naming rules:
• For a given type of structured variable, each instance must have a name that is unique within
variables of that type. However, instance names need not be unique across structured variable
types. For example, each structured variable has an instance named default, so
unique across variable types.
• The names of the components of each structured variable type must be unique across all system
variable names. If this were not true (that is, if two different types of structured variables could
share component member names), it would not be clear which default structured variable to use for
references to member names that are not qualified by an instance name.
GLOBAL
variable, a client with the
GLOBAL
variable rather than just the
GLOBAL
variable with the same name as a
[458]
[460]
[459]
Key Cache".
MyISAM
default.key_buffer_size
Using System Variables
nor SESSION, MySQL returns
GLOBAL
keyword when setting GLOBAL-only variables but not when
SESSION
variable, a client that intends to change the
GLOBAL
variable changed.
SESSION
[460]
format. Examples:
and
key_buffer_size
510
SESSION
[578] privilege might accidentally
SUPER
variable for its own connection. If we add
is always predefined. If
default
[458] both refer to the same
values.
SESSION
variable that
instance
default
is not
default