RE: Execution plan changing
- From: Yong Huang <yong321@xxxxxxxxx>
- To: mschmitt@xxxxxxxxxxxx
- Date: Sat, 15 Sep 2012 08:19:53 -0700 (PDT)
> Thanks Brandon, it looks like that confirmed the issue.
> Thanks to everyone for their help. I really appreciate it
Glad to see your problem has been solved. We recently had exactly the same
case. A DBA from another team called and asked what could have caused a query
to run with a good plan the first time and a re-run (by pressing /) uses a
different, bad, plan in his 11gR2 database. I asked what column had "Y" in
v$sql_shared_cursor for this SQL. It was use_feedback_stats for the bad cursor,
he said. So we found bugs and notes on MOS and he ran
alter session set "_optimizer_use_feedback"=false;
before re-running the query. Problem solved.
New technology may take some time to mature. For now, disabling it is a
workaround for us.
Yong Huang
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