should i remove READ UNCOMMITTED statements after i turn on Row Versioning

  • If i enable Snapshot Isolation and Row Versioning by running the following alter commands;

    ALTER DATABASE MyDatabase

    SET ALLOW_SNAPSHOT_ISOLATION ON

    ALTER DATABASE MyDatabase

    SET READ_COMMITTED_SNAPSHOT ON

    what would be the result of the stored procedures that specifically use the SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED command.

    My thought is that i should alter all the stored procedures that use it. Thoughts?

  • Correct, otherwise you're not going to use the snapshot. Snapshot Isolation is basically an option for isolation levels, and anywhere that specifically calls out a different one will ignore it. You'll want to look for NOLOCK hints too.


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  • yeah, the with (nolocks) hints i know to look out for too. Just need confirmation on dirty read behavior.

    thanks alot.

  • Geoff A (1/31/2012)


    what would be the result of the stored procedures that specifically use the SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED command.

    They run in read uncommitted isolation level. The SET TRANSACTION ISOLATION LEVEL overrides the default (read committed or read committed snapshot)

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

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