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fix: preserve adaptive IVF probe defaults (#4168)

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Keep IVF probe fields unset by default so Lance supplies adaptive
behavior. Preserve `nprobes`, `minimum_nprobes`, and `maximum_nprobes`
independently through Rust, Python, namespace, and remote request
construction, with compatibility fields serialized only when explicitly
configured.

The final Rust namespace and LSM propagation update depends on the Lance
release containing lance-format/lance#9184.
This commit is contained in:
Jack Ye
2026-10-09 12:45:02 -07:00
committed by GitHub
parent ca38924882
commit f305a05fd4
24 changed files with 576 additions and 268 deletions
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docs/web/indexing/vector-index.mdx
+5 -5
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@@ -139,9 +139,9 @@ Learn how to configure, build, and search LanceDB vector indexes, including buil
| Parameter | Description |
| :--- | :--- |
| `limit` | Number of results to return (the `k` in `k-ANN`). |
| `nprobes` | Shorthand that sets both `minimum_nprobes` and `maximum_nprobes` to the same value. LanceDB defaults this to 20 which is a good default for many cases. At very high scales you will likely need to experiment to find your preferred recall / latency balance. |
| `minimum_nprobes` | Minimum number of partitions scanned. |
| `maximum_nprobes` | Maximum number of partitions scanned. Only scans more than `minimum_nprobes` if an initial pass does not return enough results — useful for narrow filters. Set to `0` to remove the cap. |
| `nprobes` | Sets both `minimum_nprobes` and `maximum_nprobes` to the same value in Lance. Leave unset to use Lance's adaptive defaults. At very high scales you will likely need to experiment to find your preferred recall / latency balance. |
| `minimum_nprobes` | Minimum number of partitions scanned. Leave unset to use Lance's default. |
| `maximum_nprobes` | Maximum number of partitions scanned. Only scans more than `minimum_nprobes` if an initial pass does not return enough results — useful for narrow filters. Leave unset, or set to `0`, to remove the cap. |
| `ef` | HNSW search-time exploration factor. Start around `1.5 * k` and increase up to `10 * k` for higher recall. |
| `refine_factor` | Reads and reranks additional candidates in memory to recover recall lost to quantization. Start between `5` and `50` (a factor of `25` reads and reranks the top `25 * k` candidates) and measure the latency cost, typically a few milliseconds, against the recall gained. |
| `distance_range(lower_bound, upper_bound)` | Return only rows whose distance falls within `[lower_bound, upper_bound)`. Either bound is optional. Useful for near-duplicate detection or "close-enough" matching. |
@@ -165,8 +165,8 @@ older client.
| Index type | Guidance |
| :--- | :--- |
| `IVF_HNSW_FLAT`, `IVF_HNSW_SQ` | Keep the default `nprobes`, then tune `ef` first. Expect higher latency variance under filtered search. |
| `IVF_RQ`, `IVF_PQ` | Keep the default `nprobes` and raise when recall is insufficient. If using a selective filter you may need to increase `maximum_nprobes` if you do not received enough results. |
| `IVF_HNSW_FLAT`, `IVF_HNSW_SQ` | Leave the probe settings unset, then tune `ef` first. Expect higher latency variance under filtered search. |
| `IVF_RQ`, `IVF_PQ` | Leave the probe settings unset and configure them only when recall is insufficient. If using a selective filter you may need to increase `maximum_nprobes` if you do not receive enough results. |
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