DIFFERENCE BETWEEN NOLOCK VS WITH(NOLOCK) IN SQL SERVER 2008

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DIFFERENCE BETWEEN NOLOCK VS WITH(NOLOCK) IN SQL SERVER 2008

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Luis Cazares SSC Guru Points: 183706 More actions · Answer 1

Sean Lange (1/13/2014)
I will ignore your comment about suggesting that always using NOLOCK is a good idea when integrity of the results is not important. :w00t:

I'm sure he meant that WITH(NOLOCK) should always be used instead of NOLOCK only when the hint is mandatory and not when integrity of the results is not important.

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?

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Alan Burstein SSC Guru Points: 61141 More actions · Answer 2

I will ignore your comment about suggesting that always using NOLOCK is a good idea when integrity of the results is not important.:w00t:

To be clear (and to avoid being the guy who suggested someone use always use NOLOCK in any situation) I do want to point out that I included the caveat, "If NOLOCK is required..." I think my point would have been clearer if I said: If there is a requirement to use NOLOCK then use the always use WITH. That said, I can't think of a good reason to use NOLOCK and aver that a requirement that anyone must use NOLOCK is ridiculous. 😉

Edit: Just Louis' response; that is what I meant... Thank you sir.

"I cant stress enough the importance of switching from a sequential files mindset to set-based thinking. After you make the switch, you can spend your time tuning and optimizing your queries instead of maintaining lengthy, poor-performing code."

-- Itzik Ben-Gan 2001

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

Alan.B (1/13/2014)
I will ignore your comment about suggesting that always using NOLOCK is a good idea when integrity of the results is not important.:w00t:
To be clear (and to avoid being the guy who suggested someone use always use NOLOCK in any situation) I do want to point out that I included the caveat, "If NOLOCK is required..." I think my point would have been clearer if I said: If there is a requirement to use NOLOCK then use the always use WITH. That said, I can't think of a good reason to use NOLOCK and aver that a requirement that anyone must use NOLOCK is ridiculous. 😉
Edit: Just Louis' response; that is what I meant... Thank you sir.

Yes 10000% agreed. I must have misread your original post and/or was just being a pissy boy at that moment. My comment was unintentionally (and hopefully uncharacteristically) rude. My apologies if I offended you, I certainly did not mean any.

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Hany Helmy SSChampion Points: 13921 More actions · Answer 4

GilaMonster (1/9/2014)
The first is deprecated, the second is not, both can result in incorrect results, duplicate rows and missing rows, so neither is the best to use. Best is to write the SQL properly without hints.

Hi Gila,

What if we applied READ_COMMITTED_SNAPSHOT ISOLATION LEVEL on the database level? would that be enough to return only committed & not dirty data?

Thanks & Best Regards,
Hany Helmy
SQL Server Database Consultant

Sergiy SSC Guru Points: 110208 More actions · Answer 5

I would suggest (if NOLOCK is a requirement) to use NOLOCK, not WITH (NOLOCK).

NOLOCK without brackets is not a hint, but a table name alias.

So, the query would be using appropriate transaction isolation and no dirty reads would be involved.

:hehe:

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Jeff Moden SSC Guru Points: 1004318 More actions · Answer 6

Sergiy (11/4/2015)
I would suggest (if NOLOCK is a requirement) to use NOLOCK, not WITH (NOLOCK).
NOLOCK without brackets is not a hint, but a table name alias.
So, the query would be using appropriate transaction isolation and no dirty reads would be involved.
:hehe:

BWAAAA-HAAAA! (Sorry... did that come out loud?) 😛

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

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Alan Burstein SSC Guru Points: 61141 More actions · Answer 7

Sergiy (11/4/2015)
I would suggest (if NOLOCK is a requirement) to use NOLOCK, not WITH (NOLOCK).
NOLOCK without brackets is not a hint, but a table name alias.
So, the query would be using appropriate transaction isolation and no dirty reads would be involved.
:hehe:

Haha. Brilliant!

"I cant stress enough the importance of switching from a sequential files mindset to set-based thinking. After you make the switch, you can spend your time tuning and optimizing your queries instead of maintaining lengthy, poor-performing code."

-- Itzik Ben-Gan 2001