feat(iceberg): serialize DV-s to the deletion-vector-v1 blob layout - #3232
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…lob layout Add DeleteVector::serialize, which produces a deletion-vector-v1 blob that DeleteVector::deserialize reads back (apache#2580). It frames the roaring treemap as [length][magic][vector][crc], matching what deserialize reads: the roaring portable 64-bit directory (a little-endian bitmap count followed by ascending u32-keyed bitmaps), a big-endian length prefix covering the magic and vector, and a big-endian CRC-32 over the same bytes. The vector is written as-is with sparse-key encoding rather than run-length-encoded, so for the same positions the bytes need not match Iceberg-Java's BitmapPositionDeleteIndex, which run-optimizes and writes dense keys; both encodings are spec-conformant and mutually decodable. This emits the raw blob only; wrapping it in a Puffin Blob with the snapshot and sequence-number properties is left to a later change. Fold the framing into a single implementation shared by serialize and the tests, so the encode paths no longer duplicate the layout: the test-only frame_dv_blob and the encode_dv_blob helpers now delegate to serialize, and the length prefix uses a checked u32 conversion instead of a truncating cast. Round-trip tests cover an empty vector, a single position, a dense single-container run, positions spanning multiple 2^32 containers, and a run-optimized dense range, plus golden assertions on the magic offset, the length prefix, and CRC validation, and a byte-stability test that re-serializes a decoded blob to guard against container-type normalization on the round trip.
laskoviymishka
marked this pull request as ready for review
September 15, 2026 20:03
| assert_eq!(&blob[4..8], &[0xD1, 0xD3, 0x39, 0x64]); | ||
| let declared = u32::from_be_bytes(blob[..4].try_into().unwrap()); | ||
| // Everything but the length prefix and the trailing CRC is covered by `declared`. | ||
| let framing_overhead = DV_LENGTH_PREFIX_BYTES + DV_CRC_BYTES; |
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question: Just out of curiosity, why didn't you hard code 8 here instead of using the constants? Wouldn't you want to make this test as independent as possible?
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to make this a bit more self-explanatory, just having 8 means not much, but this expression has meaning, alternative would be just a comment i guess.
anoopj
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Sep 17, 2026
| let mut blob = Vec::with_capacity(DV_LENGTH_PREFIX_BYTES + body_len + DV_CRC_BYTES); | ||
| blob.extend_from_slice(&(body_len as u32).to_be_bytes()); | ||
| let body_len = | ||
| u32::try_from(body_len).expect("deletion-vector-v1 body length exceeds u32::MAX"); |
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That is a good catch. But should we do a panic here? why not return an error? I agree it is highly unlikely to get to this though, but it would be good to avoid panics.
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Which issue does this PR close?
Add DeleteVector::serialize, which produces a deletion-vector-v1 blob that DeleteVector::deserialize reads back (#2580). It frames the roaring treemap as [length][magic][vector][crc], matching what deserialize reads: the roaring portable 64-bit directory (a little-endian bitmap count followed by ascending u32-keyed bitmaps), a big-endian length prefix covering the magic and vector, and a big-endian CRC-32 over the same bytes. The vector is written as-is with sparse-key encoding rather than run-length-encoded, so for the same positions the bytes need not match Iceberg-Java's BitmapPositionDeleteIndex, which run-optimizes and writes dense keys; both encodings are spec-conformant and mutually decodable. This emits the raw blob only; wrapping it in a Puffin Blob with the snapshot and sequence-number properties is left to a later change.
Fold the framing into a single implementation shared by serialize and the tests, so the encode paths no longer duplicate the layout: the test-only frame_dv_blob and the encode_dv_blob helpers now delegate to serialize, and the length prefix uses a checked u32 conversion instead of a truncating cast. Round-trip tests cover an empty vector, a single position, a dense single-container run, positions spanning multiple 2^32 containers, and a run-optimized dense range, plus golden assertions on the magic offset, the length prefix, and CRC validation, and a byte-stability test that re-serializes a decoded blob to guard against container-type normalization on the round trip.