Hi Team,
We have upgrade our SQL server from SQL 2008 active passive cluster to SQL 2014 Always on (Side by side upgrade). After Upgrade we had serious performance issues. The proc which was taking less than 10 seconds started taking hours and never completing. We suspected infra issue, checked with infra team all was good. Checked sql config didn't find anything weird. After doing lot of R&D and trial n error we changed the database compatibility mode from SQL 2014 to SQL 2012 same proc started running in seconds.
Can you please confirm if anything has changed in SQL 2014 as this seems to be bug to us. I can provide more details if required?
Thanks-Abhijit