| Property | Description |
|---|---|
| Parameter type | Integer |
| Default value | Operating system-dependent |
| Modifiable | No |
| Range of values | 2148 to 65535 (64 KB - 1) |
| Real Application Clusters | Multiple instances must have the same value. |
PARALLEL_EXECUTION_MESSAGE_SIZE specifies the size of messages for parallel execution (formerly referred to as parallel query, PDML, Parallel Recovery, replication).
On most platforms, the default value is 2148bytes if PARALLEL_AUTOMATIC_TUNING is set to false, and 4096 bytes if PARALLEL_AUTOMATIC_TUNING is set to true. 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.