malexer commented on issue #12558: URL: https://github.com/apache/iceberg/issues/12558#issuecomment-2821532361
We’re encountering the same issue with Iceberg 1.0.0 (currently using AWS Glue 4.0). We’re trying to run a conditional MERGE operation like this: ```sql MERGE INTO target_table t USING source_table s ON t.unique_id = s.unique_id WHEN MATCHED AND t.name != s.name THEN UPDATE SET * WHEN NOT MATCHED THEN INSERT *; ``` Our intention is to update only when the name column has changed, and to skip the update if there are no changes. However, when we execute this statement multiple times with identical `target_table` and `source_table` (i.e., no actual differences), we still see a new snapshot created each time. Moreover, new data files are written to S3 with similar content and size. It appears that the UPDATE is being executed even when the `t.name != s.name` condition is not met, resulting in unnecessary file rewrites. It also undermines the ability to rely on Iceberg’s snapshot-based history for accurately tracking meaningful data changes. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For additional commands, e-mail: issues-h...@iceberg.apache.org
