[GitHub] [iceberg] liuml07 commented on a change in pull request #4272: Docs: Clarify contract for file uniqueness

[GitBox <gi...@apache.org>]

liuml07 commented on a change in pull request #4272:
URL: https://github.com/apache/iceberg/pull/4272#discussion_r832642380



##########
File path: docs/common/format/spec.md
##########
@@ -549,7 +551,10 @@ For example, an `events` table with a timestamp column named `ts` that is partit
 
 Scan predicates are also used to filter data and delete files using column bounds and counts that are stored by field id in manifests. The same filter logic can be used for both data and delete files because both store metrics of the rows either inserted or deleted. If metrics show that a delete file has no rows that match a scan predicate, it may be ignored just as a data file would be ignored [2].
 
-Data files that match the query filter must be read by the scan.
+Data files that match the query filter must be read by the scan. Note that for any snapshot, all file paths
+may appear at most once across all manifest files in the snapshot. If a file path appears more then once, the results of the scan are undefined. Reader implementations may raise an error in this case, but are

Review comment:
       I'm wondering if it's worth to add some checks in the core (e.g. introducing `FastAppend::validate` and `MergeAppend::validate`) to check if data files were appended more than once.




-- 
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-unsubscribe@iceberg.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org



---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@iceberg.apache.org
For additional commands, e-mail: issues-help@iceberg.apache.org