A MERGE statement is designed to return duplicated values of a column ID in a USING clause. The column ID is used in the merge condition. The MERGE statement contains these two clauses: WHEN NOT MATCHED THEN INSERT WHEN MATCHED THEN UPDATE What will be the result when this query is run?
Correct Answer: D
In Snowflake, MERGE statements require deterministic behavior when matching rows between the source (USING clause) and the target table. If the USING clause contains duplicate values for the join condition (in this case, column ID), Snowflake cannot deterministically decide which source row should update or insert into the target. By default, this results in an error to prevent unintended data corruption. Snowflake provides the parameter ERROR_ON_NONDETERMINISTIC_MERGE to control this behavior. When set to TRUE (the default), Snowflake raises an error if nondeterministic matches are detected. When this parameter is explicitly set to FALSE, Snowflake allows the MERGE statement to run successfully even when duplicate keys exist in the source, accepting the nondeterministic outcome (Answer D). Snowflake does not guarantee updating all or only the first occurrence in such cases; instead, the behavior is undefined unless the parameter is adjusted. This question tests an architect's understanding of data correctness, deterministic processing, and safe data engineering practices-key topics within the SnowPro Architect exam scope. =========
