Re: Updates with correlated subqueries slow after 9.2->10.2 upgrade

From: Greg Rahn <>
Date: Tue, 17 Nov 2009 14:27:10 -0800
Message-ID: <>

First, are the cardinality estimates representative? See "Using GATHER_PLAN_STATISTICS With DBMS_XPLAN.DISPLAY_CURSOR"

If the cardinality estimates are off by a significant factor, then validate your statistics. This may require a higher sample size than what is currently used.

There is no use in mucking with parameters/hints until the stats are representative.

On Tue, Nov 17, 2009 at 2:02 PM, Neil Kodner <> wrote:
> Once our environment was upgraded from to, everything
> seemed ok except for UPDATE statements that contain correlated select
> statements.  Across the board, we received poor performance compared to
> running them in 9.2.

Greg Rahn
Received on Tue Nov 17 2009 - 16:27:10 CST

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