`OpenaiReranker._rerank` asks the chat model for a relevance score per document. The model can return the documents in any order, for example sorted by score. The reranker then replaces the `text` column with the documents in that order and appends the scores in that order. The other columns keep the input order. So after a rerank, the `text` and `_relevance_score` of a row belong to a different row. The `id`, the vector and every other column still describe the original row. If the model leaves out a document, `append_column` raises `ArrowInvalid`, because the new column has fewer rows than the table. ## Fix `_rerank` keeps the `text` column unchanged, so it also keeps its position and type. It maps each score back to its row by the document content. If the model leaves out a document, `_rerank` raises a `ValueError` that gives the number of documents with no score. ## Tests `python/python/tests/test_openai_reranker.py` replaces the chat client with a stub that returns a fixed reply. The tests do not need `openai` or an API key. - One test returns the documents sorted by score. It checks that each `id` keeps its own `text` and score. On `main`, the row with id 1 gets the text `cats purr`, which belongs to id 2. - One test returns 2 of 3 documents. It checks for the `ValueError` with the count of missing documents. On `main`, the call raises `ArrowInvalid: Added column's length must match table's length`. - Both tests fail on `main` and pass with the fix. - `test_rerankers.py`: 16 passed, 13 skipped, on the lancedb 0.40.0 wheel with and without the fix. The skipped tests need real API keys. - `ruff format --check` and `ruff check` (0.9.9) pass on the changed files. - I did not build the native extension. I ran the tests against the lancedb 0.40.0 wheel with the changed file copied over it. In that wheel, `rerankers/openai.py` and `rerankers/base.py` are byte-identical to `main`. The Node SDK has no OpenAI reranker, so there is no parity change. This change does not conflict with #4515, which edits `_client` in the same file. Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
The Multimodal Lakehouse for AI
How to Install ✦ Detailed Documentation ✦ Tutorials and Recipes ✦ Contributors
The ultimate multimodal data platform for AI/ML applications.
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.
Demo: Multimodal Search by Keyword, Vector or with SQL
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Key Features:
- Fast Vector Search: Search billions of vectors in milliseconds with state-of-the-art indexing.
- Comprehensive Search: Support for vector similarity search, full-text search and SQL.
- Multimodal Support: Store, query and filter vectors, metadata and multimodal data (text, images, videos, point clouds, and more).
- Advanced Features: Zero-copy, automatic versioning, manage versions of your data without needing extra infrastructure. GPU support in building vector index.
Products:
- Open Source & Local: 100% open source, runs locally or in your cloud. No vendor lock-in.
- Cloud and Enterprise: Production-scale vector search with no servers to manage. Complete data sovereignty and security.
Ecosystem:
- Columnar Storage: Built on the Lance columnar format for efficient storage and analytics.
- Seamless Integration: Python, Node.js, Rust, and REST APIs for easy integration. Native Python and Javascript/Typescript support.
- Rich Ecosystem: Integrations with LangChain 🦜️🔗, LlamaIndex 🦙, Apache-Arrow, Pandas, Polars, DuckDB and more on the way.
How to Install:
Follow the Quickstart doc to set up LanceDB locally.
API & SDK: We also support Python, Typescript and Rust SDKs
| Interface | Documentation |
|---|---|
| Python SDK | https://lancedb.github.io/lancedb/python/python/ |
| Typescript SDK | https://lancedb.github.io/lancedb/js/globals/ |
| Rust SDK | https://docs.rs/lancedb/latest/lancedb/index.html |
| REST API | https://docs.lancedb.com/api-reference/rest |
Join Us and Contribute
We welcome contributions from everyone! Whether you're a developer, researcher, or just someone who wants to help out.
If you have any suggestions or feature requests, please feel free to open an issue on GitHub or discuss it on our Discord server.
Check out the GitHub Issues if you would like to work on the features that are planned for the future. If you have any suggestions or feature requests, please feel free to open an issue on GitHub.

