Are the posted questions getting worse?

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Are the posted questions getting worse?

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Grant Fritchey SSC Guru Points: 398882 More actions · Answer 1

Sean Lange (10/13/2016)
WOW...http://www.sql-datatools.com/2016/05/sql-queries-tuning-and-optimization.html
This is supposed to be a list of things to do to optimize queries. While some of these are valid most of them lack context or explanation. And some of them are just plain awful. :sick:

What?

"Use EXISTS instead of DISTINCT when using joins which involves tables having one-to-many relationship."

Shoot me now. Why have I bothered with three volumes of the query tuning book and (soon I hope) three volumes of the execution plans book?

"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt

Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning

Grant Fritchey SSC Guru Points: 398882 More actions · Answer 2

Sean Lange (10/13/2016)
WOW...http://www.sql-datatools.com/2016/05/sql-queries-tuning-and-optimization.html
This is supposed to be a list of things to do to optimize queries. While some of these are valid most of them lack context or explanation. And some of them are just plain awful. :sick:

I was bad. I could have ignored it. I just didn't want to.

"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt

Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning

Sean Lange SSC Guru Points: 286590 More actions · Answer 3

Grant Fritchey (10/13/2016)
Sean Lange (10/13/2016)
WOW...http://www.sql-datatools.com/2016/05/sql-queries-tuning-and-optimization.html
This is supposed to be a list of things to do to optimize queries. While some of these are valid most of them lack context or explanation. And some of them are just plain awful. :sick:
What?
"Use EXISTS instead of DISTINCT when using joins which involves tables having one-to-many relationship."
Shoot me now. Why have I bothered with three volumes of the query tuning book and (soon I hope) three volumes of the execution plans book?

I for one am quite glad you bothered. If it weren't for people like you writing these books then people like me might read articles like that and actually believe them. :w00t:

_______________________________________________________________

Need help? Help us help you.

Read the article at http://www.sqlservercentral.com/articles/Best+Practices/61537/ for best practices on asking questions.

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Cross Tabs and Pivots, Part 1 – Converting Rows to Columns - http://www.sqlservercentral.com/articles/T-SQL/63681/
Cross Tabs and Pivots, Part 2 - Dynamic Cross Tabs - http://www.sqlservercentral.com/articles/Crosstab/65048/
Understanding and Using APPLY (Part 1) - http://www.sqlservercentral.com/articles/APPLY/69953/
Understanding and Using APPLY (Part 2) - http://www.sqlservercentral.com/articles/APPLY/69954/

Sean Lange SSC Guru Points: 286590 More actions · Answer 4

Grant Fritchey (10/13/2016)
Sean Lange (10/13/2016)
WOW...http://www.sql-datatools.com/2016/05/sql-queries-tuning-and-optimization.html
This is supposed to be a list of things to do to optimize queries. While some of these are valid most of them lack context or explanation. And some of them are just plain awful. :sick:
I was bad. I could have ignored it. I just didn't want to.

I took it for "Granted" that somebody wouldn't be able to resist. 😉

_______________________________________________________________

Need help? Help us help you.

Read the article at http://www.sqlservercentral.com/articles/Best+Practices/61537/ for best practices on asking questions.

Need to split a string? Try Jeff Modens splitter http://www.sqlservercentral.com/articles/Tally+Table/72993/.

Cross Tabs and Pivots, Part 1 – Converting Rows to Columns - http://www.sqlservercentral.com/articles/T-SQL/63681/
Cross Tabs and Pivots, Part 2 - Dynamic Cross Tabs - http://www.sqlservercentral.com/articles/Crosstab/65048/
Understanding and Using APPLY (Part 1) - http://www.sqlservercentral.com/articles/APPLY/69953/
Understanding and Using APPLY (Part 2) - http://www.sqlservercentral.com/articles/APPLY/69954/

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 5

Grant Fritchey (10/13/2016)
Sean Lange (10/13/2016)
WOW...http://www.sql-datatools.com/2016/05/sql-queries-tuning-and-optimization.html
This is supposed to be a list of things to do to optimize queries. While some of these are valid most of them lack context or explanation. And some of them are just plain awful. :sick:
What?
"Use EXISTS instead of DISTINCT when using joins which involves tables having one-to-many relationship."

I can kinda see where that one comes from (though it's badly articulated). Consider:

SELECT DISTINCT CustomerName FROM Customers INNER JOIN Orders ON ... WHERE OrderStatus = 'A'

vs

SELECT CustomerName FROM Customers WHERE EXISTS (SELECT 1 FROM Orders WHERE <join> and OrderStatus = 'A')

The latter is likely to be more efficient than the former.

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

Grant Fritchey SSC Guru Points: 398882 More actions · Answer 6

GilaMonster (10/13/2016)
Grant Fritchey (10/13/2016)
Sean Lange (10/13/2016)
WOW...http://www.sql-datatools.com/2016/05/sql-queries-tuning-and-optimization.html
This is supposed to be a list of things to do to optimize queries. While some of these are valid most of them lack context or explanation. And some of them are just plain awful. :sick:
What?
"Use EXISTS instead of DISTINCT when using joins which involves tables having one-to-many relationship."
I can kinda see where that one comes from (though it's badly articulated). Consider:
SELECT DISTINCT CustomerName FROM Customers INNER JOIN Orders ON ... WHERE OrderStatus = 'A'
vs
SELECT CustomerName FROM Customers WHERE EXISTS (SELECT 1 FROM Orders WHERE <join> and OrderStatus = 'A')
The latter is likely to be more efficient than the former.

Assuming your guess is right, yeah.

"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt

Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning

Sean Lange SSC Guru Points: 286590 More actions · Answer 7

GilaMonster (10/13/2016)
Grant Fritchey (10/13/2016)
Sean Lange (10/13/2016)
WOW...http://www.sql-datatools.com/2016/05/sql-queries-tuning-and-optimization.html
This is supposed to be a list of things to do to optimize queries. While some of these are valid most of them lack context or explanation. And some of them are just plain awful. :sick:
What?
"Use EXISTS instead of DISTINCT when using joins which involves tables having one-to-many relationship."
I can kinda see where that one comes from (though it's badly articulated). Consider:
SELECT DISTINCT CustomerName FROM Customers INNER JOIN Orders ON ... WHERE OrderStatus = 'A'
vs
SELECT CustomerName FROM Customers WHERE EXISTS (SELECT 1 FROM Orders WHERE <join> and OrderStatus = 'A')
The latter is likely to be more efficient than the former.

Yes this one of them that lacks enough context to make the "tip" useful. Just a simple query like the one you posted would have made the concept clear and useful. As posted in the article it is ~~nearly~~ worthless.

_______________________________________________________________

Need help? Help us help you.

Read the article at http://www.sqlservercentral.com/articles/Best+Practices/61537/ for best practices on asking questions.

Need to split a string? Try Jeff Modens splitter http://www.sqlservercentral.com/articles/Tally+Table/72993/.

Cross Tabs and Pivots, Part 1 – Converting Rows to Columns - http://www.sqlservercentral.com/articles/T-SQL/63681/
Cross Tabs and Pivots, Part 2 - Dynamic Cross Tabs - http://www.sqlservercentral.com/articles/Crosstab/65048/
Understanding and Using APPLY (Part 1) - http://www.sqlservercentral.com/articles/APPLY/69953/
Understanding and Using APPLY (Part 2) - http://www.sqlservercentral.com/articles/APPLY/69954/

Luis Cazares SSC Guru Points: 183706 More actions · Answer 8

Grant Fritchey (10/13/2016)
Sean Lange (10/13/2016)
WOW...http://www.sql-datatools.com/2016/05/sql-queries-tuning-and-optimization.html
This is supposed to be a list of things to do to optimize queries. While some of these are valid most of them lack context or explanation. And some of them are just plain awful. :sick:
I was bad. I could have ignored it. I just didn't want to.

There seems to be more ads than good advice on that page.

Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?

How to post data/code on a forum to get the best help: Option 1 / Option 2

Ed Wagner SSC Guru Points: 287026 More actions · Answer 9

Sean Lange (10/13/2016)
Grant Fritchey (10/13/2016)
Sean Lange (10/13/2016)
WOW...http://www.sql-datatools.com/2016/05/sql-queries-tuning-and-optimization.html
This is supposed to be a list of things to do to optimize queries. While some of these are valid most of them lack context or explanation. And some of them are just plain awful. :sick:
I was bad. I could have ignored it. I just didn't want to.
I took it for "Granted" that somebody wouldn't be able to resist. 😉

I couldn't resist. I wish I would have.

Tally Tables - Performance Personified
String Splitting with True Performance
Best practices on how to ask questions

Hugo Kornelis SSC Guru Points: 64790 More actions · Answer 10

Grant Fritchey (10/13/2016)
Sean Lange (10/13/2016)
WOW...http://www.sql-datatools.com/2016/05/sql-queries-tuning-and-optimization.html
This is supposed to be a list of things to do to optimize queries. While some of these are valid most of them lack context or explanation. And some of them are just plain awful. :sick:
I was bad. I could have ignored it. I just didn't want to.

I think this one is my pesonal highlight:

IN is efficient when most of the filter criteria are in the sub-query.
EXISTS is efficient when most of the filter criteria is in the main query.

I may need to redo my reviewing work of your exec plans book after reading that page.. :w00t:

Hugo Kornelis, SQL Server/Data Platform MVP (2006-2016)
Visit my SQL Server blog: https://sqlserverfast.com/blog/
SQL Server Execution Plan Reference: https://sqlserverfast.com/epr/

Grant Fritchey SSC Guru Points: 398882 More actions · Answer 11

Hugo Kornelis (10/13/2016)
I may need to redo my reviewing work of your exec plans book after reading that page.. :w00t:

BWA-HA-HA-HA-HA!

don't you dare

</quiet voice>

"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt

Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning

Sean Lange SSC Guru Points: 286590 More actions · Answer 12

Hugo Kornelis (10/13/2016)
Grant Fritchey (10/13/2016)
Sean Lange (10/13/2016)
WOW...http://www.sql-datatools.com/2016/05/sql-queries-tuning-and-optimization.html
This is supposed to be a list of things to do to optimize queries. While some of these are valid most of them lack context or explanation. And some of them are just plain awful. :sick:
I was bad. I could have ignored it. I just didn't want to.
I think this one is my pesonal highlight:
IN is efficient when most of the filter criteria are in the sub-query.
EXISTS is efficient when most of the filter criteria is in the main query.
I may need to redo my reviewing work of your exec plans book after reading that page.. :w00t:

I liked this one.

Use stored procedures instead of views because they offer better performance and don't include code, variable or parameters that don't do anything.

How exactly does a stored procedure not include code, variables or parameters but a view does? And how about those views that have variables and parameters that don't do anything...I have no words for how awesome that is. I can't even come up with a scenario where anything in that statement could possibly be twisted to make sense.

_______________________________________________________________

Need help? Help us help you.

Read the article at http://www.sqlservercentral.com/articles/Best+Practices/61537/ for best practices on asking questions.

Need to split a string? Try Jeff Modens splitter http://www.sqlservercentral.com/articles/Tally+Table/72993/.

Cross Tabs and Pivots, Part 1 – Converting Rows to Columns - http://www.sqlservercentral.com/articles/T-SQL/63681/
Cross Tabs and Pivots, Part 2 - Dynamic Cross Tabs - http://www.sqlservercentral.com/articles/Crosstab/65048/
Understanding and Using APPLY (Part 1) - http://www.sqlservercentral.com/articles/APPLY/69953/
Understanding and Using APPLY (Part 2) - http://www.sqlservercentral.com/articles/APPLY/69954/

Ed Wagner SSC Guru Points: 287026 More actions · Answer 13

Grant Fritchey (10/13/2016)
Hugo Kornelis (10/13/2016)
I may need to redo my reviewing work of your exec plans book after reading that page.. :w00t:
BWA-HA-HA-HA-HA!
<quiet voice>
don't you dare
</quiet voice>

My favorite:

28. Include a clustered index on the columns in the GROUP BY clause.

So if I need to run queries that group the data in two different ways, I guess my options are:

1. Drop and rebuild the clustered index before I run my query.

2. Figure out how to have two clustered indexes on one table, causing the data to be stored in two different orders in the same table.

3. Duplicate the data into enough tables to have one table for each query I need to run.

What could possibly go wrong?

Tally Tables - Performance Personified
String Splitting with True Performance
Best practices on how to ask questions

Lynn Pettis SSC Guru Points: 442467 More actions · Answer 14

Ed Wagner (10/13/2016)
Grant Fritchey (10/13/2016)
Hugo Kornelis (10/13/2016)
I may need to redo my reviewing work of your exec plans book after reading that page.. :w00t:
BWA-HA-HA-HA-HA!
<quiet voice>
don't you dare
</quiet voice>
My favorite:
28. Include a clustered index on the columns in the GROUP BY clause.
So if I need to run queries that group the data in two different ways, I guess my options are:
1. Drop and rebuild the clustered index before I run my query.
2. Figure out how to have two clustered indexes on one table, causing the data to be stored in two different orders in the same table.
3. Duplicate the data into enough tables to have one table for each query I need to run.
What could possibly go wrong?

Covering indexes?

Brandie Tarvin SSC Guru Points: 173061 More actions · Answer 15

GilaMonster (10/13/2016)
Grant Fritchey (10/13/2016)
Sean Lange (10/13/2016)
WOW...http://www.sql-datatools.com/2016/05/sql-queries-tuning-and-optimization.html
This is supposed to be a list of things to do to optimize queries. While some of these are valid most of them lack context or explanation. And some of them are just plain awful. :sick:
What?
"Use EXISTS instead of DISTINCT when using joins which involves tables having one-to-many relationship."
I can kinda see where that one comes from (though it's badly articulated). Consider:
SELECT DISTINCT CustomerName FROM Customers INNER JOIN Orders ON ... WHERE OrderStatus = 'A'
vs
SELECT CustomerName FROM Customers WHERE EXISTS (SELECT 1 FROM Orders WHERE <join> and OrderStatus = 'A')
The latter is likely to be more efficient than the former.

Okay, so it's time to learn something new here... Can you point me to a reference (because I don't want to bog down The Thread on technicalities) so I can read up on why EXISTS might be more efficient than the JOIN?

Brandie Tarvin, MCITP Database AdministratorLiveJournal Blog: http://brandietarvin.livejournal.com/[/url]On LinkedIn!, Google+, and Twitter.Freelance Writer: ShadowrunLatchkeys: Nevermore, Latchkeys: The Bootleg War, and Latchkeys: Roscoes in the Night are now available on Nook and Kindle.