lancedb-gatefixer[bot] c0df2c63b6 test(rust): cover fixed-size-list merge overflow (#3907)
## Summary

- add a merge-insert regression test whose fixed-size-list child count
crosses `u32::MAX`
- verify delete-by-source updates the matching row, deletes every other
row, and completes without an Arrow panic
- use a null child array so the boundary case avoids allocating a real
vector payload

## Root cause and fix

The affected Lance merge fallback carried the target payload through a
full outer hash join. Arrow's fixed-size-list take kernel uses `u32`
child indices, so taking a target row whose child offset crossed
`u32::MAX` wrapped the offset and produced child data shorter than the
parent array, triggering the reported `ArrayData::slice` assertion.

The projection-aware merge path in the Lance version now used by `main`
avoids materializing the target fixed-size-list payload in that join.
This regression test locks in that production behavior at the exact
child-index boundary.

## Validation

- `cargo fmt --all`
- `cargo test --quiet --features remote -p lancedb
test_merge_insert_fixed_size_list_above_u32_child_count`
- `cargo check --quiet --features remote --tests --examples`
- `cargo clippy --quiet --features remote --tests --examples`

Fixes #2874

<!-- lance-gatekeeper-fix:v1 agent=582e68bcad65739e189352cb3cbf144c
generation=3 -->

Co-authored-by: Gatefixer <313497061+lancedb-gatefixer[bot]@users.noreply.github.com>
2026-08-21 16:39:13 -07:00
2023-03-17 18:15:19 -07:00
2025-03-10 09:01:23 -07:00

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LanceDB is designed for fast, scalable, and production-ready vector search. It is built on top of the Lance columnar format. You can store, index, and search over petabytes of multimodal data and vectors with ease. LanceDB is a central location where developers can build, train and analyze their AI workloads.


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