fix(arrow,maintenance): keep dict columns in batch reader; opt-in expire_snapshots file GC#15
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abnobdoss wants to merge 3 commits into
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fix(arrow,maintenance): keep dict columns in batch reader; opt-in expire_snapshots file GC#15abnobdoss wants to merge 3 commits into
abnobdoss wants to merge 3 commits into
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added 3 commits
June 23, 2026 21:27
Fixes apache#3540. to_arrow_batch_reader(dictionary_columns=...) cast each batch to a target schema built from schema_to_pyarrow(projection()), which has no dictionary types, silently decoding dictionary-encoded columns back to plain arrays (to_arrow does not, because it concatenates with permissive promotion). Derive the reader's target schema from the first scan batch so requested columns that ArrowScan actually dictionary-encodes (strings) stay dictionary typed, while columns it leaves plain (ints, ORC, etc.) stay plain - matching to_arrow. The trailing cast still conforms later batches. Adds regression tests covering string, non-string, and mixed dictionary_columns.
Fixes apache#2604. ExpireSnapshots was metadata-only and leaked the data, delete, manifest, manifest-list, and statistics files of expired snapshots forever. Add opt-in ExpireSnapshots.clean_expired_files(). On the autocommit path, collect files reachable from the expiring snapshots before the metadata commit, then after the commit collect files still reachable from every surviving snapshot (which covers all branches and tags), and best-effort delete the difference. Surviving-file resolution runs strict: if it cannot be fully resolved the cleanup aborts rather than risk deleting a live file. Statistics and partition-statistics puffin files are cleaned the same way. Cleanup is off by default and skipped for non-autocommit transactions.
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