Today’s script is to help replication performance. It was something I learned from my resident replication expert Paul Anderton. Below is a description of virtual subscriptions.
If Immediate_Sync is set when a publication is created then virtual subscriptions can occur. These can affect the "Distribution Clean Up: distribution" SQL job and the "msrepl_commands" table. By Default the job runs every 10 mins and removes replicated commands from the "msrepl_commands" table dependant on the @min_distretention value (0 hrs is default). If virtual subscriptions are present then the @min_distretention value is ignored and all replicated commands will only be removed after the @max_distretention is reached (72 hrs is default).
This script is one I have run on all my servers serving as a distributor to remove the virtual subscribers. The performance gain in all instances is fantastic the distribution clean up job runs a lot faster and replication latency (number of undistributed commands) is dramatically reduced.
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