| Property | Description |
|---|---|
| Parameter type | Integer |
| Default value | Operating system-dependent |
| Modifiable | No |
| Range of values | Minimum: 2148
Maximum: 65536, but some operating systems may have a smaller value |
| Oracle RAC | Multiple instances must have the same value. |
PARALLEL_EXECUTION_MESSAGE_SIZE specifies the size of messages used for parallel execution (formerly referred to as parallel query, PDML, Parallel Recovery, replication).
On most platforms, the default value is as follows:
16384 bytes if COMPATIBLE is set to 11.2.0 or higher
4096 bytes if COMPATIBLE is less than 11.2.0 and PARALLEL_AUTOMATIC_TUNING is set to true
2148 bytes if COMPATIBLE is less than 11.2.0 and PARALLEL_AUTOMATIC_TUNING is set to false
The default value is adequate for most applications. Larger values require a larger shared pool. Larger values result in better performance at the cost of higher memory use. For this reason, replication gets no benefit from increasing the size.
Note:
WhenPARALLEL_AUTOMATIC_TUNING is set to TRUE, message buffers are allocated out of the large pool. In this case, the default is generally higher. Note that the PARALLEL_AUTOMATIC_TUNING parameter has been deprecated.