We help IT Professionals succeed at work.
Get Started
SQL server Memory Grants and High Row Estimates
Dear all,
reading this :
http://www.brentozar.com/archive/2013/08/query-plans-what-happens-when-row-estimates-get-high/
she said :
"Here’s the general shape of our plan. Just note that the bars connecting operators are narrow– SQL Server has pretty low (and accurate) estimates of how much data will be flowing through these pipes:""
"The plan estimated cost is 1.1 and it estimates it’ll bring back 229 rows. In my test environment it takes 16 ms to run and does several thousand logical reads across the many tables it joins. This means the query optimizer didn’t consider every possible plan, but hey, our runtime was pretty darn good anyway."
how can she know "This means the query optimizer didn’t consider every possible plan, but hey, our runtime was pretty darn good anyway" ?
reading this :
http://www.brentozar.com/archive/2013/08/query-plans-what-happens-when-row-estimates-get-high/
she said :
"Here’s the general shape of our plan. Just note that the bars connecting operators are narrow– SQL Server has pretty low (and accurate) estimates of how much data will be flowing through these pipes:""
"The plan estimated cost is 1.1 and it estimates it’ll bring back 229 rows. In my test environment it takes 16 ms to run and does several thousand logical reads across the many tables it joins. This means the query optimizer didn’t consider every possible plan, but hey, our runtime was pretty darn good anyway."
how can she know "This means the query optimizer didn’t consider every possible plan, but hey, our runtime was pretty darn good anyway" ?
Why Experts Exchange?
Experts Exchange always has the answer, or at the least points me in the correct direction! It is like having another employee that is extremely experienced.
Jim Murphy
Programmer at Smart IT Solutions
When asked, what has been your best career decision?
Deciding to stick with EE.
Mohamed Asif
Technical Department Head
Being involved with EE helped me to grow personally and professionally.
Carl Webster
CTP, Sr Infrastructure Consultant
Ask ANY Question
Connect with Certified Experts to gain insight and support on specific technology challenges including:
- Troubleshooting
- Research
- Professional Opinions
Did You Know?
We've partnered with two important charities to provide clean water and computer science education to those who need it most. READ MORE