Parallel_execution_message_size
- From: Wolfson Larry - lwolfs <lawrence.wolfson@xxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Mon, 11 Oct 2004 20:15:52 -0500
Does anyone have the skinny on this? I ran into one of our DBAs from
another office and he was telling me about huge improvements in sorts, using
this.
I found the stuff below et. al., but I didn't a clear picture of how you
decide how big it should be and what all it affects.
I did see some HP example on 10G with it set to 16K.
TIA
Larry
Jeff Marsh
Optimizing Parallel Query in Oracle 8i
http://www.evdbt.com/PX%202003.pps
http://www.phptr.com/articles/article.asp?p=169538&seqNum=6
From 10G DataGuard:
Set PARALLEL_EXECUTION_MESSAGE_SIZE = 4096
When using parallel media recovery or parallel standby recovery, increasing
the PARALLEL_EXECUTION_MESSAGE_SIZE database parameter to 4K (4096) can
improve parallel recovery by as much as 20 percent. Set this parameter on
both the primary and standby databases in preparation for switchover
operations. Increasing this parameter requires more memory from the shared
pool by each parallel execution slave process.
The PARALLEL_EXECUTION_MESSAGE_SIZE parameter is also used by parallel query
operations and should be tested with any parallel query operations to ensure
there is sufficient memory on the system. A large number of parallel query
slaves on a 32-bit installation may reach memory limits and prohibit
increasing the PARALLEL_EXECUTION_MESSAGE_SIZE from the default 2K (2048) to
4K.
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