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Optimal plan Versus Execution plan [message #315478] Mon, 21 April 2008 12:50 Go to next message
shrinika
Messages: 266
Registered: April 2008
Senior Member
Hi, I have very basic question. What is the difference between Optimal plan and execution plan?

My knowledge here is, optimizer generate the optimum plan and input to row source generator. The row source generator receive the optimal plan from optimizer and output the execution plan for SQL statement.

Thanks
Re: Optimal plan Versus Execution plan [message #315487 is a reply to message #315478] Mon, 21 April 2008 13:06 Go to previous messageGo to next message
moshea
Messages: 51
Registered: February 2008
Location: Dublin, Ireland
Member
I think this may just be an issue of terminology, but to my mind.

The optimizer generates what it considers to be the optimal plan for a given query based on information available to it ie stats, histograms, whatever. However its possible that this execution plan is not in fact optimal, cos stats etc are wrong/out of date or whatever

Optimizing queries, for example, is all about, looking at the execution plan and deciding if its optimal. (ie is the query being serviced in the most efficient way).

Michael
Re: Optimal plan Versus Execution plan [message #315493 is a reply to message #315487] Mon, 21 April 2008 13:18 Go to previous message
shrinika
Messages: 266
Registered: April 2008
Senior Member
Thanks Michael
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