2.235 MEMORY_TARGET

MEMORY_TARGET specifies the Oracle system-wide usable memory.

The database tunes memory to the MEMORY_TARGET value, reducing or enlarging the SGA and PGA as needed.

Property Description

Parameter type

Big integer

Syntax

MEMORY_TARGET = integer [K | M | G]

Default value

0 (SGA autotuning is disabled for DEFERRED mode autotuning requests, but allowed for IMMEDIATE mode autotuning requests)

Modifiable

ALTER SYSTEM

Modifiable in a PDB

No

Range of values

152 MB to MEMORY_MAX_TARGET

Basic

No

MEMORY_TARGET should be set higher than or equal to the sum of the current sizes of the SGA and PGA.

In a text-based initialization parameter file, if you omit MEMORY_MAX_TARGET and include a value for MEMORY_TARGET, then the database automatically sets MEMORY_MAX_TARGET to the value of MEMORY_TARGET. If you omit the line for MEMORY_TARGET and include a value for MEMORY_MAX_TARGET, the MEMORY_TARGET parameter defaults to zero. After startup, you can then dynamically change MEMORY_TARGET to a nonzero value, provided that it does not exceed the value of MEMORY_MAX_TARGET.

Total memory usage can grow beyond the value of MEMORY_TARGET. For example, memory is allocated to PL/SQL tables and varrays regardless of the value of MEMORY_TARGET as long as memory is available at the operating system level.

In the Default value field, IMMEDIATE mode autotuning requests are necessary to avoid ORA-04031 errors. The DEFERRED and IMMEDIATE modes are reflected in the OPER_MODE column of the V$MEMORY_RESIZE_OPS view.

Note:

On Linux platforms only, Oracle recommends against explicitly setting values for MEMORY_TARGET and MEMORY_MAX_TARGET in the initialization parameter file at the time of instance startup. Doing so may result in suboptimal small page allocation in the SGA. Furthermore, if the USE_LARGE_PAGES parameter is set to ONLY and you attempt to set values for MEMORY_TARGET and MEMORY_MAX_TARGET, the instance will fail to start.

Note:

The default value of SGA_MAX_SIZE depends on the values of MEMORY_TARGET and MEMORY_MAX_TARGET.

See Also: