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Oracle 9i Explian Plan output- TOAD [message #115110] Thu, 07 April 2005 09:17 Go to next message
kumarsz
Messages: 180
Registered: March 2005
Location: canada
Senior Member

Hi
given here is an Explain Plan output in TOAD - for a sql query.
I want to know what is the parameter 'cost' here?
Does it show seconds, milliseconds, nanoseconds or it is just a comparative parameter to be used to copmare with other Explain Plan output for the same query.

Thanks in Advance
PratapC:\Documents and Settings\w1459z\My Documents\My Pictures\EXPLAIN_PLAN.bmp
Re: Oracle 9i Explian Plan output- TOAD [message #115111 is a reply to message #115110] Thu, 07 April 2005 09:28 Go to previous message
Mahesh Rajendran
Messages: 10694
Registered: March 2002
Location: oracleDocoVille
Senior Member
Account Moderator
seems your attachment of explain plan didNOT go through.
Anyhow,
COSTS within a query plan is useless. It is just derived number
The optimizer computes many criterions in many phases to come with this cost,
and uses the plan with the lowest cost.
But it doesnt mean that a plan with higher cost is bad or a plan with lower cost is better.
the tunining manual deals with this extensively.

[Updated on: Thu, 07 April 2005 09:28]

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