What to Look for in Execution Plans: Databases for Developers: Performance #3
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- čas přidán 3. 06. 2020
- You've got the plan for your SQL statement. But what do you need to change to make it faster?
This video shows you how to add I/O information to the plan. This enables you to see which steps consume the most resources, and thus where you need to focus your tuning efforts.
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The Magic of SQL with Chris Saxon
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pure gold great explanation and genius method to demostrate the concepts -- watched a few youtube items in this area and usually more confused afterwards --- not here --- thank you!
You're welcome, glad this cleared things up for you
Nice explanation.
very useful, thanks!
Very well explanation
as usual Chris' lego game is on point
Amazing
Great explanation !
goddang this is gold
Thanks! Glad you found this useful
Somewhat newbie DBA here. This information is beyond helpful - thank you so so much Chris!! I have a question about Oracle SQL Developer - is it possible to run autotrace without actually executing the SQL statement as well (I'm working with big tables in production)? I know it is possible through SQLPlus via traceonly option, just cannot tell if it's possible in Oracle SQL Developer as well.
-Thank you
To get the plan's execution stats you have to run the SQL statement!
set autotrace traceonly in SQL*Plus does execute the query, it just suppresses the output. The autotrace option in SQL Developer also executes the query, but there's no option to see the results.
If you have a long-running query and you want to see the plan before it finishes, check out the SQL monitor. You can access this in SQL Dev via Tools -> Monitor SQL. Note you need appropriate licenses to use this!
@@TheMagicofSQL I see, I will definitely try this option. Thank you!!! I really appreciate it.
I am not able to understand the autotrace part where view part individual elapsed time is 728 micro seconds. How this was calculated , Please elaborate.
Thankyou.
One more doubt , in 3rd sort operation why it dont have any elpsed time as you said in video.
I'm not sure exactly what you're referring to - please clarify. In any case, this value comes from the database measuring how long the operation took.
Again, I'm not sure exactly what you're referring to.