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AlwaysOn with backword campatibilty

Vishu 1,736 Reputation points
2021-05-29T17:30:45.957+00:00

I have an environment with databases of different compatibility 100 - 140 running on a SQL 2017 server.

  1. Will the databases with 100 compatibility support alwayson.
  2. Is it advisable to include databases with different compatibility in an availability group.
SQL Server | Other
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  1. Erland Sommarskog 122.4K Reputation points MVP Volunteer Moderator
    2021-05-29T17:42:56.433+00:00
    1. Yes, they will.
    2. There is no issue with mixing compatibility levels in an AG.

    The compatibility level controls things like what language features that are available, behavioural changes, and how the optimizer works. But it has nothing to do with the physical structure of the databsae.

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  1. AmeliaGu-MSFT 14,006 Reputation points Microsoft External Staff
    2021-05-31T03:05:06.003+00:00

    Hi @Vishu ,

    Agree with Erland. Always On works with any supported database compatibility level. For SQL Server 2017, supported database compatibility levels are 140,130,120,110,100.
    Please refer to this doc which might help.

    Best Regards,
    Amelia

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