How is @@DBTS expected to behave on an Always On Availability Group secondary replica, a Database Mirroring mirror, or a database which is being created out of a restored backup and is in standby or in-recovery state?

A coworker recently posted the following to an internal forum: “We are redirecting read load of our SSIS Packages from Primary to Secondary, and our delta logic is dependent of @@dbts values. On primary, the value of @@dbts always changes. But the same on secondary doesn’t change. Any experience around this.” And this is what…

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How to identify whether a database has participated in a cross-database transaction or in a distributed transaction

When customers evaluate using Database Mirroring or AlwaysOn Availability Groups as a HA/DR solution to protect one or more of their databases, there comes a point where they come to know there exists one documented limitation with the use of those technologies because of which it is not supported to protect databases that participate in…

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How can you drop the witness of a mirroring session when the partners have been dismantled?

A colleague of mine described the following situation: Long time ago they setup a database mirroring environment with 3 servers (2 partners + a witness). Then they changed their mind and decided that clustering fit better their HADR necessities. So they completely rebuilt the 2 partners (reinstalled operating system, etc), while forgetting to properly remove…

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Never ever set up a Database Mirroring session across different SQL Server Editions (SKU)

Even though it might work, never attempt to do that. As the documentation clearly states: it is unsupported. In topic Prerequisites, Restrictions, and Recommendations for Database Mirroring, Books Online shows a Prerequisites section where it mentions the following: Prerequisites Before you can set up database mirroring, you must perform the following: For a new mirroring…

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Launching Database Mirroring Monitor without having to go through SSMS

Yesterday, while co-delivering a seminar on Database Mirroring to a few customers, one of them asked whether it was possible to open Database Mirroring Monitor in an easier, more straight forward way than having to open SQL Server Management Studio, connecting to one instance, expanding the Databases node, right clicking on one of the databases,…

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