New Feature: "Cost Based Transformation"

From: <mccmx_at_hotmail.com>
Date: 2 Sep 2005 04:01:06 -0700
Message-ID: <1125655799.454727.139510@g49g2000cwa.googlegroups.com>

Anyone heard of this new feature in 10g: "Cost Based Transformation".

Its basically new functionality which enables the optimizer to cost transformation operations like subquery unnesting and predicate pushing etc.

I can't find any documentation on this anywhere (Metalink, google, docs.oracle.com).

Anyone have any details..?

I am seeing a huge increase in parse times when upgrading to 10g because the optimizer is churning through thousands of extra permutations with this feature enabled.

If I disable it with:

alter session set "_optimizer_cost_based_transformation" = off;

...then the parse time drops back down to 9i levels.

Matt Received on Fri Sep 02 2005 - 06:01:06 CDT