Feature: Add metadata-only replace API to Table for REPLACE snapshot operations

Start with pyiceberg/table/update/snapshot.py and the existing Table and Transaction snapshot APIs, then compare the proposed behavior with Java's RewriteFiles interface. Review tests/table/test_snapshots.py, especially test_invalid_operation(), and add focused coverage for file swaps, sequence numbers, and operation=REPLACE. Done means metadata-only replacement works atomically with Iterable[DataFile] inputs and avoids Parquet serialization.

Feature Request / Improvement

Description

This issue proposes implementing a metadata-only replace API in PyIceberg, enabling orchestrators to submit a set of DataFiles to delete and a set of DataFiles to append in a single atomic transaction.

This functionality is critical for maintenance operations such as data compaction (the "small files" problem), ensuring the logical state of the table remains unaltered while physical data layout is optimized.

Background

In a current PR (#3124, part of #1092), PyIceberg's replace semantics are tightly coupled with PyArrow dataframes (def replace(self, df: pa.Table)). This approach introduces several architectural flaws:

1. Coupling Physical Serialization with Metadata: It forces a .parquet write serialization hook directly into the snapshot commit transaction, increasing the risk of schema degradation and blocking network topologies.
2. Missing Operation.REPLACE: The current system uses primitives that log as APPEND or OVERWRITE, muddying the table history and complicating snapshot expiry/maintenance.
3. Java Inconsistency: This severely drifts from Java Iceberg's native org.apache.iceberg.RewriteFiles specification, which strictly isolates the builder into accepting purely DataFile pointers.

Proposed Solution

To fix this and achieve logical equivalence, we must implement an exact port of Java's RewriteFiles builder API into PyIceberg's native _SnapshotProducer engine.

1. Introduce _RewriteFiles Snapshot Producer:
   Add a new _RewriteFiles class that specifically targets replacing existing files. This class will implement:

   • _deleted_entries(): To find the existing target files and re-emit them as DELETED entries, defensively keeping their ancestral sequence_numbers completely intact for time travel compatibility.
   • _existing_manifests(): To scavenge unchanged manifests natively, skipping deep rewrites and only mutating manifests impacted by the deleted files.

2. Builder Hook Implementation:
   Implement UpdateSnapshot().replace() which configures the transaction with Operation.REPLACE.

3. Expose Shorthands on Table & Transaction:
   Add replace APIs on both Table and Transaction taking Iterable[DataFile] arguments to elegantly wrap the snapshot mutation:

   def replace(
       self,
       files_to_delete: Iterable[DataFile],
       files_to_add: Iterable[DataFile],
       snapshot_properties: dict[str, str] = EMPTY_DICT,
       branch: str | None = MAIN_BRANCH,
   ) -> None:
       ...
   

Notable canges

• replace() API implemented on both Table and Transaction using Iterable[DataFile].
• PyArrow .parquet write logic decoupled from the metadata transaction.
• _RewriteFiles correctly copies ancestral sequence_number pointers for DELETED and EXISTING manifest entries.
• Snapshots committed via the replace() hook possess a Summary containing operation=Operation.REPLACE.
• Unit tests pass simulating data file swaps and summary verifications.

Related Java API

Inspired heavily by Java's builder interface: https://github.com/apache/iceberg/blob/main/api/src/main/java/org/apache/iceberg/RewriteFiles.java

AI Disclosure

AI was used to help understand the code base and draft code changes. All code changes have been thoroughly reviewed, ensuring that the code changes are in line with a broader understanding of the codebase.

• Worth deeper review after AI-assistance:
• The test_invalid_operation() in tests/table/test_snapshots.py previously used Operation.REPLACE as a value to test invalid operations, but with this change Operation.REPLACE becomes valid. In place I just put a dummy Operation.
• The _RewriteFiles in pyiceberg/table/update/snapshot.py overrides the _deleted_entries and _existing_manifests functions. I sought to test this thoroughly that it was done correctly. I am thinking it's possible to improve the test suite to make this more rigorous. I am open to suggestions on how that could be done.