Steve Jones - SSC Editor (2/11/2016)

---

Ian_McCann (2/11/2016)

---

krypto69 (2/11/2016)

---

did you try changing the compatibility level to check for cardinality issues?

We have had many and some times the quick way to tell for sure is to switch it, then test.

I do not see any difference in performance between sqlserver 2014 in compatibility mode and a sql2008R2 installation.

However running in a compatibility mode is not an acceptable solution for us and we will rewrite the SP's to use a valid execution plan.

(at least, I hope we are able to do that :-))

You can set cardinality compatability for a single query/proc with an option

https://www.brentozar.com/archive/2015/06/careful-testing-the-2014-cardinality-estimator-with-trace-flags/