Just Learned - SQL Server Undocumented Query Hint - QUERYTRACEON to on the trace flags in statement level

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SQL Server Undocumented Query Hint - QUERYTRACEON to on the trace flags in statement level

Sep 5 2011 2:03AM by Ramireddy

Just learned from fabiano's article about this new undocumented query hint. "QUERYTRACEON", By using which we can switch on the trace flags with in a query statement. In below query we are applying traceflags 2389 and 2390 on below query. But this hint requires sysadmin privillege.

SELECT * FROM Sales.SalesOrderHeader
WHERE OrderDate >= Convert(date, GetDate())
OPTION(QUERYTRACEON 2389, QUERYTRACEON 2390, RECOMPILE)

6 Comments

Just be aware.... http://connect.microsoft.com/SQLServer/feedback/details/361334/the-querytraceon-option-is-not-documented

commented on Sep 5 2011 4:39PM

oeikli

730 · 0% · 44

It would be more helpful if you could say something more about traceflags 2389 and 2390. eg. Why should I use it, its benefits. etc

commented on Sep 6 2011 2:55AM

Jignesh Desai

142 · 1% · 338

Hi Jignesh,

You can find the explanation of these trace flags in the link i mentioned as original source of this post. Fabiano explained about these trace flags in very much detail. click on the link "Learned from Blog Post written by Fabiano Amorim ", which is beside my picture at the end of the post.

commented on Sep 6 2011 4:08AM

Ramireddy

2 · 41% · 12972

Got it, Thanks.

Just that the link, little goes unnoticed.

Regards

commented on Sep 6 2011 4:36AM

Jignesh Desai

142 · 1% · 338

The article by fabiano focuses more on the statistics issues with the ascending columns than the querytraces. The issue was first reported by Gail Shaw more than 6 months back.

http://sqlinthewild.co.za/index.php/2011/03/22/statistics-row-estimations-and-the-ascending-date-column/

commented on Oct 7 2011 3:30AM

Sachin Nandanwar

488 · 0% · 76

Sachin,

Yes the article is entire on a different topic, But i learned about feature "QUERYTRACEON" from the same article.

Thanks for reading...

commented on Oct 7 2011 5:20AM

Ramireddy

2 · 41% · 12972

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"SQL Server Undocumented Query Hint - QUERYTRACEON to on the trace flags in statement level" rated 5 out of 5 by 6 readers +Ramireddy