Attempt to Load Duplicate Records
| Applies To | Incremental models with primary keys for PostgreSQL and SQL Server Destinations |
| Error Message Text(s) |
For PostgreSQL: ERROR: ON CONFLICT DO UPDATE command cannot affect row a second time. Hint: Ensure that no rows proposed for insertion within the same command have duplicate constrained values. For SQL Server: The MERGE statement attempted to UPDATE or DELETE the same row more than once. This happens when a target row matches more than one source row. A MERGE statement cannot UPDATE/DELETE the same row of the target table multiple times. Refine the ON clause to ensure a target row matches at most one source row, or use the GROUP BY clause to group the source rows. |
Error Summary
This error occurs when an incremental Model attempts to insert duplicate records that share the same primary key into the output table.
Potential Cause
The Model’s SQL query generates duplicate records with the same primary key value and attempts to load those records to the output table.
Suggested Action(s)
Modify your Model’s SQL query to ensure that it does not generate duplicate values. To identify duplicate records, run the following query:
WITH base_query AS (
-- Paste your Model query here
)
SELECT
<primary_key1>,
<primary_key2>,
...
COUNT(*) AS count
FROM
base_query
GROUP BY
<primary_key1>,
<primary_key2>,
...
HAVING COUNT(*) > 1;
ORDER BY COUNT(*) DESC;
After identifying duplicates, adjust your query logic to ensure only unique rows are inserted into the output table.
Last updated on Aug 06, 2025