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Oracle9i Database Reference
Release 2 (9.2)

Part Number A96536-02
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Parameter type


Default value

Operating system-dependent

Parameter class


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.


When PARALLEL_AUTOMATIC_TUNING is set to TRUE, message buffers are allocated out of the large pool. In this case, the default is generally higher.