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PLan Cost?-Sql Tuning [message #245865]

Tue, 19 June 2007 01:53

tkmittal1
Messages: 143
Registered: May 2007
Location: Delhi

Senior Member

Hi

Can u plz tell how the oracle calculate the plan cost

regards

Tarun Mittal

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Re: PLan Cost?-Sql Tuning [message #245898 is a reply to message #245865]

Tue, 19 June 2007 03:33

Michel Cadot
Messages: 68729
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

With many and many diferent algorithms.
Read Jonathan Lewis' book: http://www.amazon.com/Cost-Based-Oracle-Fundamentals-Jonathan-Lewis/dp/1590596366/ref=sr_1_1/102-9990061-0843323?ie=UTF8&s=books& amp;qid=1182241940&sr=1-1

Regards
Michel

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Re: PLan Cost?-Sql Tuning [message #246121 is a reply to message #245898]

Wed, 20 June 2007 01:03

tkmittal1
Messages: 143
Registered: May 2007
Location: Delhi

Senior Member

How we recognised that a query is optimize or not if we have two execution plan of a particular query

Plan 1

Plan Cost 5801 Executin Time 00:00:05:965 TOTAL CPU 17.92 Physical Read 106375 Logical Read 106547 Scan Row 3 Scan Gets 3 Rowid gets 439138

Plan 2

Plan Cost 16020 Executin Time 00:00:02:775 TOTAL CPU 8.83 Physical Read 118226 Logical Read 118446 Scan Row 6071072 Scan Gets 228414 Rowid gets 0

so if we compare both the plan we found plan 2 execution time is less but plan cost is too high.

so i m confuse. How to compare execution plan's

Kindly confirm

It's urgent

it's on production

Regards

Tarun MIttal

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