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Parallel dml and blocks

From: Scrier <x3ce4unm3_at_yahoo.com>
Date: 28 Sep 2004 05:02:13 -0700
Message-ID: <6cc528c9.0409280402.ef10d23@posting.google.com>


I've been doing a lot of parallel updates lately, and monitoring them in DbArtisan, which is a third party tool. I am seeing that the sqlplus session which spawns the update becomes blocked, while the parallel slaves are processing. In some cases, SMON and QMN0 become blocked as well, and the database seems to come to a screeching halt. I've tried running sqlplus queries to determine who is blocking who, but that too becomes blocked and doesn't come back, so I've not had any luck with that query. This doesn't seem like normal behavior, and so I was wondering if anyone had any tips or pointers on why it is that SMON and QMN0 become blocked, and whether or not it was normal for the SQLPLUS session to become blocked while the slaves run. In the past when I've run parallel dml, I have not paid as much attention to the monitor, so maybe it's just gone unnoticed until now, but it is normal behavior. It doesn't seem like it would be though, because sometimes the sqlplus sessions don't become blocked. I have parallel_max_servers at 80 and am only using a degree of 8 on the statements. This is a 4 cpu box, and at most I have three scripts running, though there is other database activity at times in other schemas.

Thanks in advance,
Dennis Received on Tue Sep 28 2004 - 07:02:13 CDT

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