Skip Headers

Oracle® Database Reference 10g Release 2 (10.2) Part Number B14237-02 |
Home | Book List | Contents | Index | Master Index | Feedback

Previous | Next
| View PDF

# PGA_AGGREGATE_TARGET

Property | Description
--- | ---
Parameter type | Big integer
Syntax | `PGA_AGGREGATE_TARGET =` `integer` `[K | M | G]`
Default value | 10 MB or 20% of the size of the SGA, whichever is greater
Modifiable | `ALTER SYSTEM`
Range of values | Minimum: 10 MB Maximum: 4096 GB - 1
Basic | Yes

`PGA_AGGREGATE_TARGET` specifies the target aggregate PGA memory available to all server processes attached to the instance.

Setting `PGA_AGGREGATE_TARGET` to a nonzero value has the effect of automatically setting the `WORKAREA_SIZE_POLICY` parameter to `AUTO`. This means that SQL working areas used by memory-intensive SQL operators (such as sort, group-by, hash-join, bitmap merge, and bitmap create) will be automatically sized. A nonzero value for this parameter is the default since, unless you specify otherwise, Oracle sets it to 20% of the SGA or 10 MB, whichever is greater.

Setting `PGA_AGGREGATE_TARGET` to 0 automatically sets the `WORKAREA_SIZE_POLICY` parameter to `MANUAL`. This means that SQL workareas are sized using the `*_AREA_SIZE` parameters.

Oracle attempts to keep the amount of private memory below the target specified by this parameter by adapting the size of the work areas to private memory. When increasing the value of this parameter, you indirectly increase the memory allotted to work areas. Consequently, more memory-intensive operations are able to run fully in memory and less will work their way over to disk.

When setting this parameter, you should examine the total memory on your system that is available to the Oracle instance and subtract the SGA. You can assign the remaining memory to `PGA_AGGREGATE_TARGET`.

See Also: Oracle Database Performance Tuning Guide for more information about setting and tuning the `PGA_AGGREGATE_TARGET` parameter