Microsoft releases various service packs, cumulative updates, hotfixes for SQL Server to fix any bugs or known issues. Each of these serves different purposes. For example hotfixes address specific bug or issue and released when a customer opens a case with Microsoft and issue identified as bug, then hoxfix will be released to rectify the specific issue. So, DBAs are required to only apply the hotfix if they are facing that issue. Cumulative updates contain more number of fixes which include multiple hotfixes and additional bug fixes raised by customers. Service Packs are more higher level and contain all service packs, cumulative updates released so for for that version of SQL Server.
With each release of SQL Server version, Microsoft has been making various improvements to the product and the process based on the feedback received from the customers. For example, since SQL Server 2008, Microsoft has allowed possibility of uninstalling service packs, thus providing a better and easier way of rollback in case something goes wrong after applying the patch. Now in year 2016, Microsoft has come up with approach of recommending to install latest available service pack or cumulative update and stated that both of these will be stable as the level of testing done will be same. Previously, in DBA community, there has been assumption that service packs are more stable compared to cumulative updates, as service packs contain more fixes and tested thoroughly and thought that CUs are not tested as thoroughly as SPs.
Now with the article, Microsoft has made it clear that even service packs going forward from year 2016 are stable and recommends to install them as soon as they are available, similar to how DBAs react to release of service packs. This is due to change in the way the service packs and cumulative updates are created and tested. Microsoft has made effort to update the KB articles to reflect the same. Previously, the KB articles used to have message that “This cumulative package is intended to correct only the problems that are described in this article. Apply it only to systems that are experiencing these specific problems.”, which made many customer back down from applying the cumulative updates, but now they are updating the message with “we now recommend ongoing, proactive installation of CU’s as they become available.”
This change was welcomed by the DBA community where it makes it easier to convince the management to go ahead with applying the latest updates available from Microsoft whether it is a service pack or a cumulative update. Hope, with coming years there will be many more changes which not only improves the product, but also improves the processes.
Hope this was helpful.
This is applicable for below versions of SQL Server
SQL Server 2005
SQL Server 2008 R2
SQL Server 2012
SQL Server 2014
SQL Server 2016
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