Comments on: Interpreting Execution Plans http://www.antognini.ch/2009/10/interpreting-execution-plans/ Thu, 17 May 2012 06:56:24 +0000 hourly 1 By: Todor Botev http://www.antognini.ch/2009/10/interpreting-execution-plans/#comment-277 Todor Botev Mon, 30 Nov 2009 13:10:40 +0000 http://antognini.ch/?p=729#comment-277 I find the classification of the operations really great! With such a map in your mind it's much easier to understand what's going on. A small remark: Page 15, paragraph 3: "Operation 5 is executed eight times, once for each distinct value in the column empno in the table emp after applying the filter imposed by the operation" It seems to me that Operation 5 is executed exactly 8 times because of the filter imposed by Operation 3. So the filter of Operation 3 gets applied and only the rows satisfying it go into the filer of Operation 5. Which means "eliminate early" and somehow makes sence. I think it is not a coinsidence that exactly 8 employees do not belong to department "SALES" - meaning they satisfy the filter of Operation 3. That's why Operation 5 gets started 8 times - once for each of those employees. I find the classification of the operations really great! With such a map in your mind it’s much easier to understand what’s going on.

A small remark:

Page 15, paragraph 3:
“Operation 5 is executed eight times, once for each distinct value in the column empno in the table emp after applying the filter imposed by the operation”

It seems to me that Operation 5 is executed exactly 8 times because of the filter imposed by Operation 3. So the filter of Operation 3 gets applied and only the rows satisfying it go into the filer of Operation 5. Which means “eliminate early” and somehow makes sence.

I think it is not a coinsidence that exactly 8 employees do not belong to department “SALES” – meaning they satisfy the filter of Operation 3. That’s why Operation 5 gets started 8 times – once for each of those employees.

]]> By: ASWATH RAO http://www.antognini.ch/2009/10/interpreting-execution-plans/#comment-276 ASWATH RAO Sat, 17 Oct 2009 20:05:52 +0000 http://antognini.ch/?p=729#comment-276 Christian, I attended your session at the Open world. It was an excellent session. As you had mentioned, the room was very small and was not able to hold every one. I have put this an issue in the Open world survey too and that way they can eliminate that room in the future. Thanks again. Christian, I attended your session at the Open world. It was an excellent session. As you had mentioned, the room was very small and was not able to hold every one. I have put this an issue in the Open world survey too and that way they can eliminate that room in the future. Thanks again.

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