Why compatibilty level is important

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Why compatibilty level is important

forsqlserver

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June 9, 2011 at 1:22 am

#251478

Why compatibilty level is important?
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Gail Shaw SSC Guru Points: 1004504 More actions · Answer 1

http://www.google.com/search?q=%22compatibility+level%22

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

Basically, if the compatibility level is set to a lower value than the current value of the server, you will have reduced functionality in that database.

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GSquared SSC Guru Points: 260824 More actions · Answer 3

Because of what it is and what it does.

Do you have a more specific question? There's a lot to the subject of compatibility levels, what they do, what they don't do, etc.

(I always find it interesting how many people think setting a compatibility level back a version will allow them to restore a backup to a prior version of SQL Server.)

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SQLBalls SSCarpal Tunnel Points: 4621 More actions · Answer 4

It changes the set of rules that the Optimizer uses to validate your queries and to create execution plans.

Here is the MSDN take

http://msdn.microsoft.com/en-us/library/cc280407.aspx

It is a Myth that functionality is reduced, unless that functionality is in the Relational Engine.

http://www.sqlballs.com/search/label/backwards%20Compatibility

So far I've been able to user TDE, Compression, and Snapshots with a DB taken from 2000 and left in 80 compatibility (But all those are managed by the Storage Engine, so Test, Check, and re-test unless you KNOW what part of the engine is handling what you are attempting).

Certian Data Types can be restricted but I think there are ways to specify them you must use ANSI Standards.

I'M NOT ADVOCATING IT, JUST SAYIN!

Compatibility mode is supposed to be there to allow a quicker upgrade path, and provide developers more time to fix thier Code.

SQL only supports 3 Compat levels, so Denali will no longer support compat lvl 80. The goal isn't to leave code there, but to give you more time to get on a higher (or supported version) and not have to alter all of your app code.

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