What’s New & Undocumented in SQL Server 2019 Cumulative Update 9

Last week’s SQL Server 2019 Cumulative Update 9 snuck in some undocumented things.

We got two new DMVs for Always On Availability Groups, sys.dm_hadr_cached_replica_states and sys.dm_hadr_cached_database_replica_states. They have a subset of data from other AG DMVs:

I sure wish I could point you to the documentation or KB article on those.

But we have no idea what changed in CU9 here, or why, or what to do about it.

I’m gonna be honest with you, dear reader: I’m starting to tell clients to choose SQL Server 2017 over SQL Server 2019. 2019 just doesn’t seem like it’s baked, and