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What is post-release servicing model ?

    Question

  • Hi all, 

    I was wondering after reading SQL Server 2016 upgrade article about compatibility model while installing, there is a some line stating that "The upgrade process to enable new query processor functionality is related to the post-release servicing model of the product. Some of those fixes are released under trace flag 4199. ..", here I don't understand what is post-release servicing model.

    Read from below url

    https://docs.microsoft.com/en-us/sql/database-engine/install-windows/change-the-database-compatibility-mode-and-use-the-query-store

    Could anyone explain what is that ?


    Maharajan

    Monday, March 27, 2017 1:40 AM

Answers

  • Hotfixes can introduce new behaviors that are hidden behind trace flags. Here's a more thorough explanation:

    1. While in servicing, we protect every query plan impacting change by putting it under Trace Flag 4199 (unless this is a fix for severe issue like incorrect results, which are extremely rare) to avoid plan changes within the same version.
    2. In the next major release, we move those changes under the new db compat level so that the trace flag is no longer needed to enable the same fixes under the new db compat level.
    3. Ones we ship vNext RTM and it enters servicing, the same approach (1)-(2) repeats.


    This posting is provided "AS IS" with no warranties, and confers no rights.

    Wednesday, March 29, 2017 2:36 PM
    Moderator

All replies

  • Hi Maharajan,

    Please refer to the following KB for more information on post-release servicing model: https://support.microsoft.com/en-us/help/974006/sql-server-query-optimizer-hotfix-trace-flag-4199-servicing-model

    Thanks,

    Jeff


    This posting is provided "AS IS" with no warranties, and confers no rights.

    Monday, March 27, 2017 11:22 PM
    Moderator
  • Hi Jeff,

    Thank you for your reply.

    So I can assume that it is a kind of hotfix issued by MS after release ?


    Maharajan

    Tuesday, March 28, 2017 12:23 AM
  • Hotfixes can introduce new behaviors that are hidden behind trace flags. Here's a more thorough explanation:

    1. While in servicing, we protect every query plan impacting change by putting it under Trace Flag 4199 (unless this is a fix for severe issue like incorrect results, which are extremely rare) to avoid plan changes within the same version.
    2. In the next major release, we move those changes under the new db compat level so that the trace flag is no longer needed to enable the same fixes under the new db compat level.
    3. Ones we ship vNext RTM and it enters servicing, the same approach (1)-(2) repeats.


    This posting is provided "AS IS" with no warranties, and confers no rights.

    Wednesday, March 29, 2017 2:36 PM
    Moderator