Посмотри BOL: Replication\Types of Replication\Transactional Replication\How Transactional Replication Works

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Data modifications made at the Subscriber will always be propagated as a series of single row statements, provided they do not modify a uniquely constrained column. If an UPDATE does modify a uniquely constrained column, the UPDATE will be propagated as a series of DELETE statements followed by a series of INSERT statements. A uniquely constrained column is any column participating in a unique index or clustered index, even if the clustered index is not declared as unique. UPDATES made to indexed views or base tables that indexed views are based on will be propagated as DELETE/INSERT pairs.