If restoring backups of SQL 2005 DBs onto a SQL 2014 can they be kept in v9.0 and should still work & run?
 
If not do I need to run SQL 2014 Upgrade Advisor & if yes does this have a performance impact?
 
Thanks in advance.

When you restore a database to the high compatability or version of sql server upgrade process will automatically do it for you.

Yes there are some performance impacts. It depends on what features are you using in your 2005 database.

here is the link for more information;

https://msdn.microsoft.com/en-us/library/ms177429.aspx?f=255&MSPPError=-2147217396

Hello,

As you can read in the following resources, compatibility level 90 is not supported on SQL Server 2014.

https://connect.microsoft.com/SQLServer/feedback/details/793444/is-compatibility-level-sql-server-2005-90-supported-in-sql-server-2014

https://msdn.microsoft.com/en-us/library/bb510680.aspx

About SQL Server Upgrade Advisor impact on performance, please read the following thread:

https://social.msdn.microsoft.com/Forums/sqlserver/en-US/de29b904-0a20-4673-9ea5-fa7007e6c15c/performance-cost-running-sql-2008-upgrade-advisor?forum=sqlsetupandupgrade

Hope this helps.

Regards,

Alberto Morillo
SQLCoffee.com

• Edited by Alberto MorilloMVP, Moderator 5 hours 41 minutes ago

If restoring backups of SQL 2005 DBs onto a SQL 2014 can they be kept in v9.0 and should still work & run?
 
If not do I need to run SQL 2014 Upgrade Advisor & if yes does this have a performance impact?
 
Thanks in advance.

Please note that whatever method of upgrade you use be it side by side or in place its always advisable to run Upgrade advisor. Upgrade advisor points out to breaking changes in 2014

When you restore 2005 backup on 2012 the moment restore finishes database is upgraded to 2014. But yes you can keep compatibility level to 90 and this would allow some legacy features to work. But you must be aware about how application would behave. Please read changing compatibility level