Sql Server distribution database non-clustered index

sreejitg 41 Reputation points


Does Microsoft recommend/support to create non-clustered index in distribution database table Msrepl_commands? Our informatica CDC queries is running longer and execution plan suggest 99% impact to create missing non-clustered index. Once we created the non-clustered index the perf issue stand fixed but double checking if Microsoft support creating indexes in system databases?


SQL Server
SQL Server
A family of Microsoft relational database management and analysis systems for e-commerce, line-of-business, and data warehousing solutions.
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  1. Tom Phillips 17,706 Reputation points

    MS does not support user changes to MS supplied databases. They can be changed during patching/upgrade and cause a conflict.

    However, there is nothing to stop you from doing it, with the understanding it might break something later.

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  2. Seeya Xi-MSFT 16,411 Reputation points

    Hi @sreejitg ,

    No, this is not recommended/supported. But this does not mean that you cannot create those indexes.
    Microsoft does not support making any changes to the system tables (replication, logshipping).
    Index creation is not free, since SQL Server has to maintain any DDL changes that means you will have to do a proper maintenance for those indexes.
    Finally, it is important to note that do not just blindly create them unless you have tested and proven that they will benefit your workload.

    Best regards,

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