Would SQL Azure Compatibility Level affect performance?

Question

I have a V11 Database on a Compatibility Level of 100.

I have a V12 Database on a Compatibility Level of 120.

a) What does 100 mean?

b) If I changed the compatibility level on the V11 to 110, would it affect performance?

b) If I changed the compatibility level on the V12 to 110, would it affect performance?

Answer 1

You can get details about compatibility levels here. Essentially this is used to be compatible to the previous versions of SQL. To answer your question about performance, I would quote this paragraph from MSDN article:

Compatibility level affects behaviors only for the specified database, not for the entire server. Compatibility level provides only partial backward compatibility with earlier versions of SQL Server. Starting with compatibility mode 130, any new query plan affecting features have been added only to the new compatibility mode. This has been done in order to minimize the risk during upgrades that arise from performance degradation due to query plan changes. From an application perspective, the goal is still to be at the latest compatibility level in order to inherit some of the new features as well as performance improvements done in the Query optimizer space but to do so in a controlled way.

Hope this helps! Silvia Doomra