We have a two replica 2017 Standard Availability Group in asynchronous mode. With a failover (manual/forced, since can't do automatic), we have the potential for overlapping/reused identity values if the secondary is lagging behind the primary. This is really bad for us...CustomerA seeing CustomerB's data.
EDIT: I'm mostly concerned about a DR/failure failover where the primary goes offline unexpectedly. A planned failover (patching, etc.) would be easier to manage by waiting for or forcing the secondary to sync up to the primary before taking the primary offline, as suggested below.
Is there a way to automatically run a script as the secondary takes over the primary role, to bump all identity columns (DBCC CHECKIDENT RESEED) to allow for the eventual merging of the old primary's unsynced records?
Since this is Standard, the secondary is inaccessible until it takes over as the primary, so when/how would the script run?
Side question: Since the old primary becomes the secondary (once it's back online) and is at that point inaccessible (Standard), how does one run queries on it to determine the unsynced records? Back up/restore the old primary as a nonAG db?