Is there such thing as a trigger for Availability Group failovers?

I want a certain action to happen when an AG fails over. Specifically, I want to turn on a database setting (turning on RCSI). I want to do this on a failover in order to minimize disruption to 24/7 workloads and scheduled maintenance windows are hard to come by.

I know that sp_procoption can be used to mark procedures as startup procedures. This seems like it could work for failover clusters, but not for Availability Groups.

I did consider adding an alert (sp_add_alert) on message_id=26069 in order to respond to failover actions with a sql agent job. But this seems less direct and in practice it seems slow

  • Is this a common thing others would want? Or is it just me? – Michael J Swart Apr 17 '19 at 19:16
  • Hmm, what’s the advantage of not having RCSI enabled on the secondary by default? Is it because of the additional versioning information? (If so I Wonder if this is actually a bad thing to not have slots for versioning in your existing rows)? – eckes Apr 17 '19 at 21:18
  • You can’t have different RCSI settings on primary and secondary. Any queries that read on the secondary node run under Snapshot isolation any way. – Michael J Swart Apr 17 '19 at 22:53
  • If you cannot have different settings I don’t understand what the trigger should do? – eckes Apr 17 '19 at 22:55
  • I wanted to change the setting during a failover. The timing was the important part. The change in the RCSI setting takes a small outage, so does the failover. I wanted one to happen at the same time as the other. – Michael J Swart Apr 18 '19 at 0:18

No. Triggers are not at an instance or AG level. You'd need to base something on the failover event or better yet, as part of a SQL Server Agent job, just check to see if that replica is the primary and then do (or not do) something.


I've done things like this before, but all I found available was the alerts. There's actually 2 different alerts, one that fires for each database in the AG, and another that fires when the entire AG fails over. So you have some flexibility.

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