[bug] partial `OVERWRITE` operation writes the wrong snapshot summary metrics

[kevinjqliu]

Apache Iceberg version

main (development)

Please describe the bug 🐞

Snapshot OVERWRITE operation can calculate the wrong summary fields when the table is partially updated.

update_snapshot_summaries assumes that all OVERWRITE operations are full table overwrite https://github.com/apache/iceberg-python/blob/322ebdd1a6e4870e7f0bdbdf74ca2a04b0ce5d7f/pyiceberg/table/update/snapshot.py#L239 https://github.com/apache/iceberg-python/blob/322ebdd1a6e4870e7f0bdbdf74ca2a04b0ce5d7f/pyiceberg/table/snapshots.py#L358-L359

This is likely an oversight when we implemented partial write.

Thankfully the table/transaction's overwrite function is currently implemented as a delete+append.

The only place where OVERWRITE operation is used is during partial deletes. https://github.com/apache/iceberg-python/blob/322ebdd1a6e4870e7f0bdbdf74ca2a04b0ce5d7f/pyiceberg/table/init.py#L678

Original thread https://github.com/apache/iceberg-go/pull/356#issuecomment-2746317666 (thanks @arnaudbriche and @zeroshade )

Partial overwrite reproduced in #1840

Willingness to contribute

• [x] I can contribute a fix for this bug independently
• [ ] I would be willing to contribute a fix for this bug with guidance from the Iceberg community
• [ ] I cannot contribute a fix for this bug at this time

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This issue has been closed because it has not received any activity in the last 14 days since being marked as 'stale'