June 10, 2014 at 3:00 am
Hi all,
I am not sure whether it's kind of silly to ask this question. However, someone asked me this question and since, I am just a starter wasn't able to convince the guy. Okay...the question goes something like this. In case if we are upgrading our instances and moving to a higher version for e.g 2008 -> 2012. What will be the impact on the compatibility settings for those user db's. For e.g if my compatibility for a user db is set to be 100 then will it be able to maintain the code features from 2008 (backward compatible) and will it also be able to use the new features of SQL 2012 (basically if it's set to 100...how will it use SQL 2012 features). May I know what happens majorly when you perform an upgrade...what is that feature which has a major effect or is it that everything remains as it is and only the t-sql engine changes.
Pls. provide your valuable response on this to enhance my knowledge on the subject.
Regards,
Faisal
June 10, 2014 at 4:02 am
If you have tested and result set are giving correct output than you can keep the upgraded version of the database i.e. 110 elase you can change it back to 100.
Refer following link for further details.
http://technet.microsoft.com/en-us/library/bb510680(v=sql.110).aspx
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June 10, 2014 at 4:10 am
Thanks! mascot but this doesn't really answer my question. Pls. share your thoughts/experience about this stuff. I'm sure there might be people in this forum who might be knowing about the internals of it.
Regards,
Faisal
June 10, 2014 at 5:02 am
Compatibility mode is supposed to be a temporary fix as part of the migration of your database to the new server, allowing time for the code and application to catch up to the changes prior to switching on the full functionality of the new version of SQL Server. By and large, the internals for your database on the new server are going to match the internals of the new version of SQL Server. It's more an external set of behaviors that is enabled by using the compability mode. But for a detailed list of exactly how this behavior is set, refer to the books online. They detail which of the compatibility levels is supported and which of those functionalities will be modified by the compatibility level.
Most of the functional differences won't affect people too much in most situations. The biggest issue I've hit is the changes in reserved words. That requires not just changes to code, but changes to structures. But, you should know about this going in because you should always use the Upgrade Advisor prior to migrating the database. It will identify breaking changes like reserved words that you can get to work fixing before you migrate rather than after.
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