Using Automatic Shared Memory Management (97)

You enable the automatic shared memory management feature by setting the
SGA_TARGET parameter to a non-zero value. This parameter in effect replaces the
parameters that control the memory allocated for a specific set of individual
components, which are now automatically and dynamically resized (tuned) as needed.

Note: The STATISTICS_LEVEL initialization parameter must be set
to TYPICAL (the default) or ALL for automatic shared memory
management to function.

The SGA_TARGET initialization parameter reflects the total size of the SGA. Table2–3
lists the SGA components for which SGA_TARGET includes memory—the
automatically sized SGA components—and the initialization parameters
corresponding to those components.

In addition to setting SGA_TARGET to a non-zero value, you must set the value of all
automatically sized SGA components to zero to enable full automatic tuning of these
components.

Alternatively, you can set one or more of the automatically sized SGA components to a
non-zero value, which is then used as the minimum setting for that component during
SGA tuning. This is discussed in detail later in this section.

Note: An easier way to enable automatic shared memory
management is to use Oracle Enterprise Manager (EM). When you
enable automatic shared memory management and set the Total SGA
Size, EM automatically generates the ALTER SYSTEM statements to
set SGA_TARGET to the specified size and to set all automatically sized
SGA components to zero.
If you use SQL*Plus to set SGA_TARGET, you must then set the
automatically sized SGA components to zero or to a minimum value.

The V$SGA_TARGET_ADVICE view provides information that helps you decide on a
value for SGA_TARGET.

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