If the primary key columns that the Applier uses to identify rows in a target table are frequently updated on the source, enable this optimization for the table to improve Merge Apply performance. The Applier optimizes processing of Updates if the mapped table has a virtual index that meets the following requirements:

If a virtual index that meets these requirements does not exist, create one. The Applier requires this virtual index to identify the target rows to which to apply the pair of Delete and Insert operations for an Update.

If a mapped table has other virtual indexes for which both the

Unique

and

Supplemental logging

options are selected, clear one of these options for each of the virtual indexes. By clearing an option, you increase the priority of the unique index that includes all of the table columns and decrease the priority of the other virtual indexes. The Applier then uses the unique index with the highest priority to identify the target rows when applying a pair of Delete and Insert operations for optimized Update processing.