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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