qzyu999 commented on code in PR #3131:
URL: https://github.com/apache/iceberg-python/pull/3131#discussion_r3983953126
##########
pyiceberg/table/update/snapshot.py:
##########
@@ -852,6 +850,120 @@ def _get_entries(manifest: ManifestFile) ->
list[ManifestEntry]:
return []
+class _RewriteFiles(_SnapshotProducer["_RewriteFiles"]):
+ """A snapshot producer that rewrites data files.
+
+ Produces a REPLACE snapshot that swaps existing data files for new ones
without
+ changing the logical contents of the table. This is the metadata-only
operation
+ used by compaction (bin-packing, sort, format migration).
+
+ Current scope:
+ - Data file rewriting only (delete + add DataFiles)
+ - Validates: files-to-delete exist, added_records <= deleted_records,
+ no new delete files conflict with replaced data files
+
+ Future work (additive — no structural changes needed):
+ - Delete-file rewriting (add _deleted_delete_files set + separate
manifest handling)
+ - dataSequenceNumber override (pin new files' seq to match replaced,
for eq-delete safety)
+ - validateFromSnapshot (expose _starting_snapshot_id setter for
long-running planners)
+ - ignoreEqualityDeletes in validation (coupled with dataSequenceNumber)
+ """
+
+ def _commit(self) -> UpdatesAndRequirements:
+ # Only produce a commit when there is something to rewrite
+ if self._deleted_data_files or self._added_data_files:
+ # Grab the entries that we actually found in the table's manifests
+ deleted_entries = self._deleted_entries()
+ found_deleted_files = {entry.data_file for entry in
deleted_entries}
+
+ # If the user asked to delete files that aren't in the table,
abort.
+ if len(found_deleted_files) != len(self._deleted_data_files):
+ raise ValidationException("Cannot commit, missing data files
to be rewritten that are not in the table")
+
+ added_records = sum(f.record_count for f in self._added_data_files)
+ deleted_records = sum(entry.data_file.record_count for entry in
deleted_entries)
+
+ if added_records > deleted_records:
+ raise ValidationException(
+ f"Invalid replace: records added ({added_records}) exceeds
records removed ({deleted_records})"
+ )
+
+ return super()._commit()
+ else:
+ return (), ()
+
+ @cached_property
+ def _cached_deleted_entries(self) -> list[ManifestEntry]:
Review Comment:
Done, `_cached_deleted_entries` and the executor/manifest-scanning
boilerplate now live in `_SnapshotProducer`. Each subclass just overrides
`_get_deleted_manifest_entries(manifest)` to control which entries get marked
as `DELETED`. `_OverwriteFiles` adds partition-level evaluator pruning in its
override; `_RewriteFiles` matches on `_deleted_data_files` directly.
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