## Summary
This updates the Java API reference to close the documentation gaps that
can be fixed from the current Java source and generated namespace API.
The patch adds an empty table example, shows how to wrap returned Arrow
IPC query bytes in a reusable `ArrowFileReader` helper, and documents
the Java index operations that are currently exposed by the namespace
client: vector indexes, scalar indexes, full text search indexes, and
listing indexes.
## Issue Links
Fixes https://github.com/lancedb/docs/issues/157
Fixes https://github.com/lancedb/docs/issues/160
Partially addresses https://github.com/lancedb/docs/issues/159 by
documenting the index parameters currently exposed by Java. The
requested `num_partitions` example is still blocked because
`CreateTableIndexRequest` does not expose IVF training parameters yet.
Not included: https://github.com/lancedb/docs/issues/158. The current
Java docs and source remain remote namespace oriented, so local DB
connection documentation should wait until the Java local DB API is
available and can be verified.
## Validation
- Built the Java core module with OpenJDK 17:
`./mvnw -pl lancedb-core -am -DskipTests compile`
- Checked the Markdown diff:
`git diff --check -- docs/src/java/java.md`
The Java build succeeds. It still reports pre-existing checkstyle
warnings in the namespace client builder, but the Maven build is green.
## Summary
- reconstruct foreign Arrow Map schemas from their single sanitized
entries field
- reject malformed Map types with anything other than one child
- preserve the complete Map schema and `keysSorted` value through
empty-table creation and IPC round trips across Arrow 15–18
## Testing
- `./node_modules/.bin/jest --runInBand __test__/arrow.test.ts
__test__/sanitize.test.ts`
- `pnpm lint`
- `pnpm build`
- `pnpm run docs`
Fixes#2337
## What
- Replace legacy model names in `WatsonxEmbeddings` with the current
supported set:
- `ibm/granite-embedding-278m-multilingual` (new default, 768-dim)
- `ibm/slate-125m-english-rtrvr-v2` (768-dim)
- `ibm/slate-30m-english-rtrvr-v2` (384-dim)
- `intfloat/multilingual-e5-large` (1024-dim)
- `sentence-transformers/all-minilm-l6-v2` (384-dim)
- Add `space_id` field — mutually exclusive with `project_id`, mirrors
the
existing pattern in `WatsonxReranker`
- `project_id` / `space_id` resolution now falls back to
`WATSONX_PROJECT_ID` /
`WATSONX_SPACE_ID` env vars; exactly one must be supplied
## Why
The previously hardcoded models (`ibm/slate-125m-english-rtrvr`,
`sentence-transformers/all-minilm-l12-v2`) are legacy and no longer
listed as
supported by the watsonx.ai platform. `space_id` scoping was already
supported
by `WatsonxReranker` but was missing from the embeddings counterpart.
---------
Co-authored-by: Will Jones <willjones127@gmail.com>
Updates the Rust workspace Lance dependencies and Java lance-core from
v9.1.0-beta.5 to v9.1.0-beta.7, including the generated Cargo lockfile.
No LanceDB compatibility changes were required for this release. See the
[Lance v9.1.0-beta.7
release](https://github.com/lance-format/lance/releases/tag/v9.1.0-beta.7).
This PR adds some support for `diff` / `merge` in the remote client as
for local tables we stay `NotSupported` until
https://github.com/lance-format/lance/issues/7263.
This wires the two review-and-land calls against the remote REST API:
- `POST /v1/table/{id}/branches/diff`
- `POST /v1/table/{id}/branches/merge`
Rust gets typed results (`BranchDiff`, `MergeBranchResult`). Python
returns the wire JSON, same shape as the REST response.
Merge here means promoting a branch's added columns onto `main`.
### Behavior
- Remote only. Local raises `NotSupported`.
- A rejected merge is not an exception. HTTP 409 still returns `Ok` / a
dict with `status="rejected"` and blockers in `diff.mergeBlockers`.
- Unknown blocker / status codes parse as `Unknown` so a newer server
does not break older clients.
- `MergePreview` tolerates missing fields for the same reason.
- Merge requests are not retried. 409 is final and carries the body you
need.
### Example
```python
table = db.open_table("images")
table.branches.create("exp")
exp = table.branches.checkout("exp")
exp.add_columns({"tag": "cast('draft' as string)"})
diff = table.branches.diff("exp")
preview = table.branches.merge("exp", dry_run=True)
result = table.branches.merge("exp", dry_run=False)
if result["status"] == "merged":
print("landed at", result["mainVersionAfter"])
elif result["status"] == "rejected":
print(result["diff"]["mergeBlockers"])
```
### Testing
cargo test -p lancedb --features remote diff_branch
cargo test -p lancedb --features remote merge_branch
---------
Co-authored-by: Cursor <cursoragent@cursor.com>
## Problem
On the remote (LanceDB Cloud) write path, each write partition is
uploaded as a **single** `/insert?upload_id=...` request that stays open
until the whole partition has been streamed and the server has written
it to object storage. For large bulk ingests a partition can be many GB,
so a single request can run longer than the client read timeout (default
300s), surfacing as:
```
lancedb.remote.errors.HttpError: operation timed out
```
The server already supports staging **multiple** parts under one
`upload_id` (each `/insert` writes a separate transaction that
`complete` merges atomically), but the client never used that — it sent
one part per partition.
## Change
Split each partition into multiple parts of at most
`max_bytes_per_request` (Arrow IPC, LZ4-compressed) bytes, each uploaded
as its own `/insert?upload_id=...&upload_part_id=...` request. This
bounds how long any single request stays open, independent of total data
size or write parallelism.
Key properties:
- **Still streamed, not buffered.** Each part's body is driven through a
bounded channel while the request is in flight (`futures::join!` of a
producer + the send), so peak memory stays at a couple of batches per
partition regardless of the part size. Backpressure from a
slow/throttled server still propagates upstream.
- **Correct part accounting.** An empty partition still sends exactly
one (schema-only) part so `complete` has a transaction to commit; a size
cut landing exactly on the end of input does not emit a trailing empty
part.
- **Multipart only.** The single-request (non-multipart) path is
unchanged.
## Config
New `ClientConfig::max_bytes_per_request: Option<usize>`, also settable
via the `LANCE_CLIENT_MAX_BYTES_PER_REQUEST` environment variable.
**Default 1 GiB** (`Some(0)` disables splitting → one request per
partition). Python users pick up the default/env automatically through
the remote client.
## Tests
- `test_multipart_chunked_splits_into_parts`: a 1-byte budget puts each
batch in its own part → N requests, each carrying the shared `upload_id`
and a distinct `upload_part_id`.
- `test_multipart_single_part_when_under_budget`: a large budget keeps
the partition in a single request.
- Verified end-to-end against a live remote table: a forced-chunked
multipart add (many parts) assembles to the correct row count.
Related to ENT-1883.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
## Summary
Fixes#1653.
`infer_vector_column_name` in `util.py` could silently return `None`
when `query is None` and `query_type` is not `"fts"` or `"hybrid"`. This
`None` then propagated into downstream code, causing a cryptic
`TypeError: expected bytes, NoneType found` rather than a clear error
message.
## Changes
- **Removes the no-op `try/except Exception as e: raise e`** around
`inf_vector_column_query` (it was catching and immediately re-raising
without adding any value)
- - **Adds a `None` guard** after the inference block: if
`vector_column_name` is still `None` at this point, raise a clear
`ValueError` pointing the user to pass `vector_column_name` explicitly
## Before / After
**Before:** cryptic `TypeError: expected bytes, NoneType found` deep in
schema lookup code
**After:**
```
ValueError: No vector column found in the schema. Please specify the vector column name explicitly via the `vector_column_name` parameter.
```
---------
Co-authored-by: Will Jones <willjones127@gmail.com>
Some additions to our lancedb skill to enable agents to use the jobs
methods that we recently added. Eval tests (below, with and without
these additions to the skill) suggest that they're helping, mostly to
find the right method calls. These are a little unusual because they
require REST server connection, they're not yet implemented in the SDKs.
```
┌─────────────────────┬───────────┬────────────┬─────────────┬──────────┬───────────┬──────────┬───────────┐
│ eval │ grade w/o │ grade with │ improvement │ time w/o │ time with │ cost w/o │ cost with │
├─────────────────────┼───────────┼────────────┼─────────────┼──────────┼───────────┼──────────┼───────────┤
│ 8-list-running-jobs │ 2.5/3 │ 3/3 │ +0.5 │ 123s │ 29s │ $0.58 │ $0.18 │
├─────────────────────┼───────────┼────────────┼─────────────┼──────────┼───────────┼──────────┼───────────┤
│ 9-describe-job │ 1/5 │ 5/5 │ +4.0 │ 159s │ 52s │ $0.62 │ $0.25 │
├─────────────────────┼───────────┼────────────┼─────────────┼──────────┼───────────┼──────────┼───────────┤
│ 10-cancel-job │ 3/3 │ 3/3 │ +0.0 │ 99s │ 35s │ $0.55 │ $0.21 │
├─────────────────────┼───────────┼────────────┼─────────────┼──────────┼───────────┼──────────┼───────────┤
│ TOTAL │ 6.5/11 │ 11/11 │ +4.5 │ 381s │ 116s │ $1.75 │ $0.65 │
└─────────────────────┴───────────┴────────────┴─────────────┴──────────┴───────────┴──────────┴───────────┘
```
Failure reasons are because the agent didn't know the right method to
call, spent all its turns guessing REST calls, tried to inspect lancedb
code, but didn't find the answer in here.
## Problem
`table.add(dataset)` with a `pyarrow.dataset.Dataset` OOMs the client
during bulk ingestion of wide rows (e.g. embedding columns), even
against a remote table where the upload itself is streaming.
The cause is in `to_scannable`: a `Dataset` is scanned with pyarrow's
default scanner settings (`batch_size=131072` rows,
`batch_readahead=16`, `fragment_readahead=4`). pyarrow's internal
threads prefetch that read-ahead window independently of LanceDB's
backpressure, so for wide rows a large fraction of the dataset is held
in memory. On the remote path this is then multiplied across the
multipart write partitions (one in-flight batch per partition, up to
CPU-core count).
Reproduced on a 10 GB / 1.55M-row dataset with two 768-dim float32
embeddings: peak client RSS ~11.7 GB for the scan alone (6.8 GB after
consuming a *single* batch), ~15.4 GB for the full remote `add()`.
## Fix
`to_scannable` now sizes the scanner from an estimate of bytes-per-row
derived from the schema:
- **Narrow datasets keep pyarrow's defaults** (empty scanner kwargs) —
no throughput regression. The bound only engages above ~410 bytes/row.
- **Wide rows** get a smaller `batch_size` (~16 MiB/batch) and reduced
read-ahead (`batch_readahead=2`, `fragment_readahead=1`) so peak
in-flight memory stays near a ~1 GiB budget. Read-ahead (not just batch
size) has to drop, because pyarrow pins whole row-group buffers.
On the 10 GB dataset this drops peak client RSS to ~1.4 GB, and it stays
flat as the dataset grows. The `Dataset`/`LanceDataset` scannables
remain rescannable (retry-safe).
## Also: expose `write_parallelism` on `add()`
`AddDataBuilder::write_parallelism` already existed in Rust but was not
exposed in Python. This PR forwards it through the async, sync, and
remote `add()` methods, so users can cap the number of parallel write
partitions (each buffers data in flight) to trade throughput for memory
on large uploads.
## Tests
- `test_scannable.py`: bytes-per-row estimation; narrow → defaults; wide
→ bounded; `Dataset` reader streams bounded batches and stays
rescannable.
- `test_table.py`: `write_parallelism` on sync and async `add()`, and
that `write_parallelism=0` is rejected.
Fixes ENT-1883
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Moves the skill from .agents/skills/lancedb to
plugins/lancedb/skills/lancedb, as recommended by codex and claude.
Install path now is:
### Codex/ChatGPT app
Codex: Plugins -> "Create" arrow -> Add plugin marketplace
search for lancedb plugin and install
### Codex CLI
```
codex plugin marketplace add lancedb/lancedb
codex plugin install lancedb@lancedb # name@marketplace
```
### Claude app
Settings -> Plugins -> Add -> Add marketplace
search for lancedb plugin and install
### Claude CLI
```
claude plugin marketplace add lancedb/lancedb
claude plugin install lancedb@lancedb
```
Here's how it looks on ChatGPT/Codex app:
(the main icon has light and dark modes; the smaller one on the skill
doesn't so I made it gray 🤷 )
<img width="764" height="560" alt="Screenshot 2026-07-16 at 2 49 24 PM"
src="https://github.com/user-attachments/assets/b82cda16-3392-4740-ac47-b2f187cb2655"
/>
Hi, and thank you for LanceDB.
Small CI supply-chain hardening. In `make-release-commit.yml`, the
release job checks out with `LANCEDB_RELEASE_TOKEN` (a push-capable PAT)
and its final step pushes the version tag using a third-party action
pinned to a **mutable branch**:
```yaml
- name: Push new version tag
uses: ad-m/github-push-action@master
with:
github_token: ${{ secrets.LANCEDB_RELEASE_TOKEN }}
```
`@master` can move after review; whatever it points at then runs with
that release token in scope. This PR pins it to the commit behind the
current release (`v1.3.0` → `881a6320…`), keeping the version visible as
a comment. Behavior today is unchanged.
For transparency: I used AI assistance to spot and draft this; I
verified the workflow and resolved the SHA myself.
Tracks #3324. On x86_64 CPUs without AVX2 (Sandy Bridge / Ivy Bridge /
Westmere on Intel; Bulldozer / Piledriver / Steamroller on AMD), `import
lancedb` SIGILLs because the wheel bakes AVX2 + FMA into every compiled
function. Per [westonpace's
review](https://github.com/lancedb/lancedb/issues/3324#issuecomment-4328944354),
the default `lancedb` wheel stays fast; pre-Haswell users get a
separately-published `lancedb-compat` wheel.
## Summary
- Adds a `lancedb-compat` matrix entry to `pypi-publish.yml` that builds
with `RUSTFLAGS="-C target-cpu=x86-64-v2"` (Nehalem-class baseline).
Same Python API (`import lancedb` works) — files install to the same
namespace, so the two wheels conflict at install time and users pick
one. Same pattern as `psycopg2` / `psycopg2-binary` and `tensorflow` /
`tensorflow-cpu`.
- Generalizes `build_linux_wheel` and `upload_wheel` composites with
optional `package-name` and `rustflags` inputs (defaults preserve the
existing 4 `lancedb` matrix entries verbatim).
- Documents the choice in `python/README.md`: `pip install
lancedb-compat` for pre-Haswell hosts.
The default `.cargo/config.toml` baseline is unchanged.
## Sequencing
1. ~~lance-format/lance#6630 merges → runtime SIMD dispatch lands in
lance.~~ **Done — merged.**
2. lancedb's lance dep is bumped to a release that includes it (separate
PR / normal cadence).
3. This PR's `lancedb-compat` wheel build path starts producing a wheel
that runs on pre-Haswell hardware. **Maintainer setup**: register
`lancedb-compat` on PyPI and configure trusted publishing.
## Verified end-to-end on Sandy Bridge Xeon E5-2609
Verification was done locally against a fork-pinned lance dep that
includes the runtime dispatch implementation, using the same
`RUSTFLAGS="-C target-cpu=x86-64-v2"` flags this PR uses in CI:
```
$ RUSTFLAGS="-C target-cpu=x86-64-v2" maturin build --release
$ pip install ./target/wheels/lancedb-*.whl
$ python verify.py
PASS: import + simd dispatch + table create + vector search all work.
```
Pre-fix on the same CPU (default `pip install lancedb`): `Illegal
instruction (core dumped)`. Full reproducer (deps + clone + build +
verification):
https://gist.github.com/tobocop2/2e341358b55c143527416edfdb1e37df.
Fork-internal verification PR with the dep bump and full logs:
[`tobocop2/lancedb#2`](https://github.com/tobocop2/lancedb/pull/2).
## Benchmarks — no regressions on modern CPUs from the lance-side change
These are the numbers I ran for the lance PR, confirming the runtime
dispatch doesn't slow down the default (`target-cpu=haswell`) wheel that
existing users install. Criterion, one machine, one session, base → PR,
no `RUSTFLAGS` override. Full methodology, null experiments, and logs:
[lance-format/lance#6630 benchmark
comment](https://github.com/lance-format/lance/pull/6630#issuecomment-4933063394)
and the [logs
gist](https://gist.github.com/tobocop2/3c6d0f449cbd736aa2501f89a7fe56a2).
| benchmark | EPYC 7B13 (`avx2`, `fma`, no `avx512f`) | Xeon Cascade
Lake (`avx512f`) |
|---|---|---|
| `Cosine(f32, scalar)` *(control)* | +0.04% | +0.09% |
| `Cosine(f64, scalar)` | −0.34% | −1.94% |
| `Cosine(u8, SIMD)` | +2.30% | +3.63% |
| `Dot(f16, SIMD)` | −0.58% | +0.61% |
| `Dot(f32, SIMD)` | +0.34% | **−6.08%** |
| `Dot(f32, arrow_arity)` | +0.02% | −0.00% |
| `L2(f32, scalar)` | −0.10% | −0.02% |
| `L2(f32, simd)` (dim 1024) | +2.63% | −0.53% |
| **`L2(simd,f32x8)` (dim 8)** | **−45.9%** | **−25.1%** |
| `L2(u8, SIMD)` | +0.42% | −3.11% |
| `NormL2(f32, SIMD)` | −1.02% | −4.17% |
| `NormL2(f64, SIMD)` | +3.51% | −0.58% |
Nothing regresses beyond the noise floor. Dim 8 — the PQ sub-vector
width — improves 25–46%.
---
To be transparent: this isn't my domain of expertise and the lance-side
implementation is AI-generated. I verified it works end-to-end on the
failing hardware. Happy to roll in feedback.
Routes local sync child-namespace operations through the Rust-backed
connection instead of the Python namespace-client fallback.
Also keeps lazy namespace-client construction for table-to-Lance
conversion and preserves public namespace error mappings.
Validated locally with ruff format/check and targeted namespace pytest.
BREAKING CHANGE: splits generated by the permutation data loader will
not be the same, due to a change in hash function.
Updates the Lance dependencies and Java lance-core to
[v9.0.0-rc.1](https://github.com/lance-format/lance/releases/tag/v9.0.0-rc.1).
Includes the required DataFusion 54 and Lance file-reader compatibility
updates.
---------
Co-authored-by: Will Jones <willjones127@gmail.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Adds client-side support for analyze_plan distributed metrics modes
across Rust, Python, and TypeScript clients. Defaults to aggregate for
backward compatibility and sends the remote distributed_metrics
parameter only when a non-default mode is requested.
Fixes#3174
Also fixes#3645
Empty record batches now append correctly typed empty embedding arrays
without invoking embedding providers. This avoids OpenAI requests with
an invalid empty input while preserving source-column validation and
the non-empty execution paths.
As a small cleanup, the single- and multi-embedding code paths now share
a single upfront lookup of their source columns ("input_columns")
instead
of each path looking them up independently. Also moves `lance-testing`
from regular dependencies to dev-dependencies where it belongs.
Tests run:
- `cargo fmt --all -- --check`
- `cargo test --quiet -p lancedb --lib
empty_batch_skips_embedding_functions`
- `cargo test --quiet -p lancedb --lib
empty_batch_still_validates_source_column`
- `cargo test --quiet -p lancedb --lib
test_create_empty_table_with_embeddings`
- `cargo check --quiet -p lancedb --features remote --tests --examples`
- `cargo clippy --quiet -p lancedb --features remote --tests --examples`
- `cargo test --quiet -p lancedb --lib`
- `cargo test --quiet --features remote --tests`
## Summary
Fix `on_bad_vectors="fill"` so it replaces only invalid or missing
vector values instead of replacing the entire vector row.
Fixes#3026.
## Reasoning
The old Python sanitizer detected whether a vector row was bad at row
granularity. For `fill`, it then used that row-level flag to replace the
whole vector with `[fill_value] * dim`. That meant an input like `[1.0,
NaN, 3.0]` became `[0.0, 0.0, 0.0]`, even though the documented and more
useful behavior is to preserve valid values and fill only the bad
element.
I checked whether this should be a Rust-side fix so TypeScript users
would benefit too. Today, Rust core exposes `NaNVectorBehavior::{Error,
Keep}` for rejecting or keeping NaN vectors, while the Python
`on_bad_vectors` API (`error`, `drop`, `fill`, `null`) is implemented in
the Python ingestion sanitizer before data reaches Rust. TypeScript does
not expose the Python `on_bad_vectors="fill"` behavior today. Moving
this exact behavior to Rust would be a broader cross-language API
change, so this PR keeps the fix scoped to the currently affected Python
API.
## What changed
- Added a small helper that fills bad vector rows by preserving valid
elements, replacing NaN elements with `fill_value`, truncating vectors
longer than the expected dimension, and padding short vectors with
`fill_value`.
- Kept the existing fast path unchanged: the helper only runs after bad
vectors are detected and `on_bad_vectors="fill"` is selected.
- Updated sanitizer and table tests to assert element-wise NaN
replacement and short-vector padding for both `create_table` and `add`.
## Validation
- `uv run ruff format .`
- `uv run ruff check .`
- `cd python && uv run --no-sync pytest
python/tests/test_util.py::test_handle_bad_vectors_jagged
python/tests/test_util.py::test_handle_bad_vectors_nan
python/tests/test_table.py::test_create_with_nans
python/tests/test_table.py::test_add_with_nans -vv`
Targeted pytest result: `10 passed`.
## Why this fix is Python-side (and not Rust)
The problematic behavior lives in Python’s `on_bad_vectors` sanitizer,
before data is handed off to Rust. Rust currently only exposes
`NaNVectorBehavior::{Error, Keep}` for add operations, while Python has
the richer `on_bad_vectors={"error","drop","fill","null"}` API.
TypeScript does not currently expose the Python-style fill behavior, so
moving this exact fix into Rust would require designing a broader
cross-language bad-vector handling API.
This PR keeps the change scoped to the existing affected surface:
Python’s `on_bad_vectors="fill"` path. This way, Python users
immediately benefit.
## What the new agent skill covers
We want to help users _easily_ write LanceDB pipelines to bring their
data in from other places, no matter whether they use LanceDB OSS or
Enterprise.
The `lancedb` set of skills contains guidance for agents on the
following:
- Distinguishes local and remote table capabilities.
- Promotes bounded reads using `select()` and `limit()`.
- Prevents accidental full-table materialization.
- Documents correct Python sync/async scan APIs.
- Recommends validated Python schemas and batched ingestion.
- Provides indexing, query-tuning, diagnostics, and maintenance
guidance.
- Documents the Enterprise table-name cache issue: avoid immediately
reusing a dropped or overwritten table name; write to a fresh name and
rename after propagation.
- Adds Python and TypeScript API, pattern, and performance references.
- Adds a heuristic scanner for potentially unsafe Python and TypeScript
materialization patterns.
This change only adds agent documentation and tooling: no LanceDB
runtime code, Rust code, SDK APIs, dependencies, or CI configuration are
modified.
## Context
The LanceDB agent skill was accidentally pushed directly to `main` in
`8ea78e3fbcb26718112ab4ddec55a91804b869d3`, bypassing the normal review
workflow. That commit was reverted on `main` by `c12a6dce` so the
protected branch is back to its prior content.
## Summary
- add table-level FTS query tokenization returning token text and
position
- use the native index tokenizer for local tables and remote index
metadata for remote tables
- expose sync and async Python table wrappers with focused coverage
`Dataset::index_statistics()` loads index files and does meaningful CPU
work to serialize low-level info. Most fields
`NativeTable::index_stats()` needs are available from manifest metadata
via `Dataset::describe_indices()`, which is much cheaper.
`NativeTable::index_stats()` now:
- Calls `describe_indices()` filtered by name; returns `Ok(None)` if no
match.
- Parses `distance_type` from `description.details()` JSON (the
`VectorIndexDetails` proto stored in the manifest by recent Lance
versions).
- Falls back to `index_statistics()` only for vector indices where
`details()` returns no `distance_type` — this handles older Lance
datasets that didn't write `VectorIndexDetails`.
- `Unknown` index types (e.g. Lance's internal `FragReuseIndex`) are
explicitly filtered out of `list_indices` rather than erroring.
## Test plan
- [x] `test_create_scalar_index` — asserts `index_type`,
`distance_type`, and `num_unindexed_rows > 0` after adding rows
post-index
- [x] `test_create_fm_index`, `test_create_bitmap_index`,
`test_create_label_list_index` — added `index_stats` assertions
- [x] IvfPq, IvfHnswPq, IvfHnswSq, IvfHnswFlat tests assert
`distance_type == Some(L2)`
- [x] `test_list_indices_skip_frag_reuse` — FragReuseIndex is filtered
by the Unknown guard in `list_indices`
---------
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
## Summary
- serialize sync phrase queries consistently for execution and query
plans
- restore the documented no-argument hybrid `phrase_query()` behavior
- keep reranker input as the original user text without mutating the
builder
Fixes#3653.
## Testing
- `python/.venv/bin/python -m pytest <8 focused test nodes> -q` (`8
passed`)
- `python/.venv/bin/python -m ruff format --check
python/python/lancedb/query.py python/python/tests/test_fts.py
python/python/tests/test_hybrid_query.py`
- `python/.venv/bin/python -m ruff check .`
- `git diff --check origin/main...HEAD`
The complete hybrid module and the real native FTS phrase test were not
completed
in the current PyO3 runtime environment: both stalled in the native
`lancedb.connect()` fixture and were interrupted without an assertion
failure.
The CODEOWNERS file added in #3312 automatically requests reviewers on
every PR — the `*` default owner routes all changes to two reviewers.
This is mostly noise for contributors, and we prefer a single requested
reviewer per PR.
Remove the file.
Reverts #3312.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Carrying over from #2915, this patch introduces:
* Single-API call batching support for Gemini embeddings (up to 100 at a
time, the API limit)
* A versioned user agent header for Gemini API calls
* Support for [variable embedding dimension
size](https://ai.google.dev/gemini-api/docs/embeddings#control-embedding-size)
(Gemini is MRL trained)
## Summary
- preserve explicit `0.0` distance bounds in synchronous hybrid search
- distinguish omitted `None` endpoints from zero-valued endpoints when
configuring the vector child query
- add a public end-to-end regression test for a zero upper bound
## Testing
- `cd python && uv run --extra tests pytest
python/tests/test_hybrid_query.py -q`
- `uv run --project python ruff format --check
python/python/lancedb/query.py python/python/tests/test_hybrid_query.py`
- `uv run --project python ruff check .`
Fixes#3651
The `build - aarch64-pc-windows-msvc` node build job (and, marginally,
the x86_64 one) had started hitting `rustc-LLVM ERROR: out of memory`
while linking the `lancedb-nodejs` cdylib — most recently surfaced by
#3526, which adds the goosefs backend (and its tonic/prost gRPC subtree)
to the default node binary.
The peak-memory step is the fat-LTO codegen (`lto=fat`,
`codegen-units=1` from `.cargo/config.toml`), which merges the whole
crate graph into a single LLVM module and runs single-threaded. It
therefore neither parallelizes across cores nor fits in the 16 GB of the
standard `windows-latest` runner as the dependency graph grows.
This PR:
- Moves both `*-pc-windows-msvc` node build jobs to
`windows-2025-8x-x64` (more memory + cores).
- Overrides the release profile to ThinLTO for just these jobs, via
`CARGO_PROFILE_RELEASE_LTO=thin` /
`CARGO_PROFILE_RELEASE_CODEGEN_UNITS=16` in `pre_build`. ThinLTO
parallelizes the cross-module optimization across the runner's cores and
keeps peak memory well under the limit. Scoped so Python wheels and Rust
release builds keep fat LTO.
The larger runner alone would clear the OOM but waste the added cores on
the single-threaded fat-LTO tail; ThinLTO is what makes the extra cores
actually reduce wall-clock and gives durable memory headroom for future
dependency growth.
Tradeoff: ThinLTO can leave a small runtime-perf gap vs fat LTO for the
node native binary, but it recovers most of it and is a common release
configuration.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Bridges Lance's internal `metrics`-crate instrumentation (object store
request counts, bytes, latency, errors, and throttles) into
OpenTelemetry, in both the Python and Node bindings, with a shared
adapter in the Rust core. This is the LanceDB counterpart to
lance-format/lance#7537.
## Rust core (`rust/lancedb`)
Two new, **off-by-default** features:
- `metrics` — re-exports the [`metrics`](https://docs.rs/metrics) crate
as `lancedb::metrics` and turns on Lance's object-store instrumentation.
Install any `metrics`-compatible recorder to collect them.
- `metrics-otel` — adds `lancedb::metrics_otel`, a pull-based adapter
that installs a process-global recorder aggregating into lock-free
cumulative storage and exposes a snapshot/catalog API
(`register_metrics_recorder`, `metrics_catalog`, `snapshot_metrics`,
`MetricPoint`/`MetricValue`/`MetricKind`/`MetricDescription`). Both
bindings build on this.
## Python
`lancedb.otel.instrument_lancedb_metrics()` registers each metric as an
OpenTelemetry observable instrument on the given (or global)
`MeterProvider`. Available via the `otel` extra (`pip install
lancedb[otel]`), which pulls in only `opentelemetry-api` — the
application supplies and configures the SDK.
## Node
`instrumentLanceDbMetrics()` provides the equivalent wiring against
`@opentelemetry/api`. This is the only public entry point; the
underlying recorder/catalog/snapshot functions stay internal.
Because OpenTelemetry has no asynchronous histogram instrument,
histograms are exported Prometheus-style as `<name>_bucket` (with an
`le` attribute), `<name>_count`, and `<name>_sum`. Only `_sum` carries
the histogram's unit; `_bucket` and `_count` observe cumulative counts
and are unitless. The adapter is enabled by default in the Python and
Node builds, and off by default in the Rust crate.
## Notes
- Requires Lance ≥ `v9.0.0-beta.19`, which ships the object-store
metrics APIs (upstream lance-format/lance#7537, now merged). `main` is
already on beta.19, so this is a single feature commit with no
dependency bump.
- Tests: 8 Rust unit tests, 3 Python tests, 2 Node tests, all covering
the end-to-end object-store-metrics → OpenTelemetry path.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Bumps Lance to v9.0.0-beta.19, which includes lance-format/lance#7687
for side-effect-free DirectoryNamespace read paths.
This fixes root-level read-only table opens that previously could
trigger `__manifest` creation through directory namespace construction,
including Hugging Face bucket reads with read-only tokens. A LanceDB
regression test now covers root listing operations without creating
`__manifest`.
Fixes#3633.
### Summary
`flatten_columns` raises `ValueError` when called with `flatten=False`,
even though `False` should mean "do not flatten". This is reachable from
the public API — `Query.to_pandas(flatten=...)` and
`to_batches(flatten=...)` type their `flatten` param as
`Optional[Union[int, bool]]` and pass it straight to `flatten_columns`.
### Cause
`bool` is a subclass of `int`, so `isinstance(False, int)` is `True`.
`flatten=False` skips the `flatten is True` check, falls into the
integer branch, and `False <= 0` evaluates to `True`, raising:
```
ValueError: Please specify a positive integer for flatten or the boolean value `True`
```
### Reproduction
```python
import lancedb
db = lancedb.connect("/tmp/db")
t = db.create_table("t", data=[{"id": 1, "vector": [0.1, 0.2]}])
t.search([0.1, 0.2]).to_pandas(flatten=False) # -> ValueError
```
### Fix
Guard the integer branch with `not isinstance(flatten, bool)` so that
`flatten=False` (and `None`) mean "do not flatten". Behavior is
otherwise unchanged:
- `flatten=True` → flatten all nested levels
- positive `int` → flatten to that depth
- non-positive `int` (e.g. `0`) → still rejected with `ValueError`
Added a regression test in `tests/test_util.py` covering `None`,
`False`, `True`, a positive depth, and `0`.
This PR fixes a serialization error when using Ollama embeddings in
`create_table`.
The use of `@cached_property` for the Ollama client was causing issues
during serialization/pickling, which is required by certain LanceDB
operations (like when using multiprocessing or certain storage
backends). Switching to a standard `@property` ensures the client is
instantiated when needed without being stored in a way that breaks
serialization.
Verified with the following script:
```python
import lancedb
from lancedb.embeddings import get_registry
import pickle
registry = get_registry().get(\"ollama\")
model = registry(name=\"llama3\")
# This would fail before the fix
pickled = pickle.dumps(model)
unpickled = pickle.loads(pickled)
```
Fixes#2629 (or similar serialization issues reported).
---------
Co-authored-by: Unmilan Mukherjee <Missing-Identity@users.noreply.github.com>
## Summary
Closes#3525
This PR wires up two new optional object-store backends at the LanceDB
layer, exposing capabilities that already exist upstream in `lance` /
`lance-io`:
| Backend | Cargo feature | Default in Rust crate | Default in Python
wheel | Default in Node binding |
| --- | --- | --- | --- | --- |
| **Tencent COS** | `cos` | ❌ off | ✅ on | ❌ off |
| **GooseFS** | `goosefs` | ❌ off | ✅ on | ✅ on |
Both backends are additive and do not affect existing users who don't
opt in.
## Motivation
- **Tencent COS** is the dominant object storage in the China region.
Tencent Cloud users currently need an S3-compatible proxy or a private
fork to use LanceDB against COS buckets.
- **GooseFS** is Tencent Cloud's distributed cache acceleration layer
that sits in front of COS/S3, a common pattern for vector search / AI
training where the same hot dataset is read repeatedly.
- This brings COS / GooseFS to feature parity with the existing
first-class backends (`aws`, `gcs`, `azure`, `oss`, `huggingface`).
See the linked issue #3525 for the full discussion.
## Changes
### `rust/lancedb/Cargo.toml`
Add two new optional features that pull through the corresponding
upstream feature flags:
```toml
cos = ["lance/tencent", "lance-io/tencent"]
goosefs = [
"lance/goosefs",
"lance-io/goosefs",
"lance-namespace-impls/dir-goosefs",
]
```
### `python/Cargo.toml`
Enable both `cos` and `goosefs` by default for the Python wheels, so
`pip install lancedb` works against COS / GooseFS out of the box
(consistent with how `aws` / `gcs` / `azure` / `oss` are bundled today):
```diff
-default = ["remote", "lancedb/aws", "lancedb/gcs", "lancedb/azure", "lancedb/dynamodb", "lancedb/oss", "lancedb/huggingface"]
+default = ["remote", "lancedb/aws", "lancedb/gcs", "lancedb/azure", "lancedb/dynamodb", "lancedb/oss", "lancedb/huggingface", "lancedb/cos", "lancedb/goosefs"]
```
### `nodejs/Cargo.toml`
Enable `goosefs` by default for the Node binding (COS kept opt-in to
limit the default native binary size; can be revisited based on demand):
```diff
-default = ["remote", "lancedb/aws", "lancedb/gcs", "lancedb/azure", "lancedb/dynamodb", "lancedb/oss", "lancedb/huggingface"]
+default = ["remote", "lancedb/aws", "lancedb/gcs", "lancedb/azure", "lancedb/dynamodb", "lancedb/oss", "lancedb/huggingface", "lancedb/goosefs"]
```
### `Cargo.lock`
Regenerated to reflect the transitive dependencies brought in by the new
upstream features. No manual edits.
## Example Usage
### Rust
```toml
# Cargo.toml
lancedb = { version = "0.30", features = ["cos", "goosefs"] }
```
```rust
// Tencent COS
let db = lancedb::connect("cos://my-bucket/my-db").execute().await?;
// GooseFS
let db = lancedb::connect("goosefs://my-namespace/my-db").execute().await?;
```
### Python
```python
import lancedb
db = lancedb.connect(
"cos://my-bucket/my-db",
storage_options={
"secret_id": "...",
"secret_key": "...",
"region": "ap-guangzhou",
},
)
```
## Backwards Compatibility
- All new features are **opt-in** at the Rust crate level (`default =
[]` for `lancedb` itself is unchanged).
- The Python wheel gains both backends by default, increasing wheel size
slightly but matching the existing pattern of bundling all major cloud
backends.
- Node binding only adds `goosefs` to defaults; existing users see no
behavior change.
## Testing
- `cargo check --all-features` ✅
- `cargo check -p lancedb --features cos` ✅
- `cargo check -p lancedb --features goosefs` ✅
- End-to-end COS / GooseFS smoke tests require Tencent Cloud credentials
and are intentionally not added to CI in this PR (same approach used for
`s3-test`). Happy to add a gated test feature in a follow-up if
reviewers prefer.
## Checklist
- [x] Added `cos` and `goosefs` features to `rust/lancedb/Cargo.toml`
- [x] Updated `python/Cargo.toml` default features
- [x] Updated `nodejs/Cargo.toml` default features
- [x] Regenerated `Cargo.lock`
- [x] Verified build with `--all-features`
- [ ] Documentation update (can be done in a follow-up PR once API
stabilizes)
## Related
- Issue: #3525
- Upstream support:
[`lance/tencent`](https://github.com/lance-format/lance),
[`lance/goosefs`](https://github.com/lance-format/lance)
## Summary
Adds `Table::get_lsm_write_spec` returning `Option<LsmWriteSpec>` — the
read counterpart to the existing `set_lsm_write_spec` /
`unset_lsm_write_spec`. Returns `None` when the MemWAL LSM write path is
not enabled; otherwise reconstructs the spec (mode, shard column,
`num_buckets`, `maintained_indexes`, `writer_config_defaults`) exactly
as installed.
## Changes
- **Rust core (`NativeTable`)** — reconstructs the spec from
`mem_wal_index_details()`, resolving the shard column from its Lance
field id via the dataset schema. This is a raw metadata read, so it is
unaffected by `describe_indices` system-index filtering.
- **Remote (`RemoteTable`)** — reads the `__lance_mem_wal` system index
through `index/list` with `include_system: true` (so the curated
`list_indices` surface stays unchanged), then parses the index `details`
JSON. It matches the index by name and ignores `index_type`, so no
client `IndexType` variant is needed. It uses the **server-resolved
`column` name** from the details (Lance field ids do not travel to the
remote client).
- **Python + TypeScript bindings** — sync and async, mirroring
`set`/`unset`, with round-trip tests (bucket / identity / unsharded,
plus `None` when unset).
## Tests
- Rust: native round-trip unit test + remote mock-endpoint tests
(present + absent). All green (`cargo test --features remote -p
lancedb`).
- Python/TS: round-trip tests added; binding-runtime execution runs in
CI.
## Dependencies for the remote path
The remote path is complete on the client side but depends on two
out-of-repo pieces to work end-to-end:
1. **lance** — emit the server-resolved shard **`column`** name in the
MemWAL index `details` JSON (field ids can't reach the client). See
lance-format/lance#7667.
2. **server** — honor `include_system` on `index/list` so the
`__lance_mem_wal` entry is returned for this read.
Against an older server (no `include_system`), the remote getter
degrades gracefully to `Ok(None)` rather than erroring.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Updates LanceDB's Lance dependencies to v9.0.0-beta.18.\n\nThis
refreshes the Rust workspace lockfile and Java lance-core version using
the repository update script. Triggering Lance tag:
https://github.com/lancedb/lance/releases/tag/v9.0.0-beta.18
Closes#3245.
> **BREAKING CHANGE:** `with_format("torch")` no longer returns a list
of stacked row tensors. It now returns per-row dicts so PyTorch's
default `DataLoader` collate stacks them into `{col: tensor(B,)}`.
Switch to `with_format("torch_row")` to keep the old shape.
### What changed
`"torch"` now returns a list of per-row dicts (`[{col: tensor}, ...]`)
at every indexed access path. The default `DataLoader` collate stacks
them into a column-keyed batched dict, no custom `collate_fn` needed.
The old shape is preserved under a new `"torch_row"` literal.
`"torch_col"` is unchanged.
The unbatching lives inside the transform (`batch_to_tensor_dict`), not
`__getitems__`, so the shape survives pickling and works under
`DataLoader(num_workers>0, multiprocessing_context="spawn")`.
### Format comparison
| Format | `iter(batch_size=N)` | `__getitems__([0,1,2])` | `DataLoader`
default collate |
|---|---|---|---|
| `"torch"` (new) | `list[{col: tensor}]` length N | `list[{col:
tensor}]` length 3 | `{col: tensor(B,)}` |
| `"torch_row"` (old `"torch"` behavior) | `list[tensor(n_cols,)]`
length N | `list[tensor(n_cols,)]` length 3 | `tensor(B, n_cols)` |
| `"torch_col"` (unchanged) | `tensor(n_cols, N)` | `tensor(n_cols, 3)`
| needs `collate_fn=lambda x: x` |
Output matches HuggingFace `Dataset.set_format("torch")` on container
shape, keys, and values at every access path. The only divergence:
HuggingFace downcasts `float64` to `torch.float32` by default, LanceDB
preserves dtype. Verified by `scripts/verify_torch_format.py`.
### Migration
```python
# Old default — column names lost, shape was tensor(B, n_cols)
DataLoader(Permutation.identity(table).with_format("torch"))
# New default — column names preserved
DataLoader(Permutation.identity(table).with_format("torch")) # {col: tensor(B,)}
# Keep old behavior
DataLoader(Permutation.identity(table).with_format("torch_row")) # tensor(B, n_cols)
```
Fixes#3296
## Problem
The repository has no `CODEOWNERS` file, so there is no enforced review
routing for sensitive areas such as release workflows, auth code, and
FFI boundaries. This means changes to critical paths can be merged
without an explicit codeowner review.
## Solution
Add `.github/CODEOWNERS` covering:
- `/.github/workflows/` — release/publish workflows (supply chain risk)
- `/rust/lancedb/src/remote/` — remote client & auth code
- `/python/src/` and `/nodejs/src/` — FFI language boundaries
The listed owners (`@jackye1995`, `@wjones127`, `@Xuanwo`, `@AyushExel`)
are based on recent merge activity. Feel free to adjust to match the
actual team structure or replace with GitHub team handles if preferred.
## Testing
No code change — only adds a metadata file. GitHub will start routing
review requests automatically once this is merged and branch protection
is configured to require codeowner approval.
Co-authored-by: octo-patch <octo-patch@github.com>
### **Summary**
Closes#3212
Extends the Python `lit()` helper to natively support three additional
types (`date`, `datetime`, and `Decimal`) and implements reflexive
operators for the `Expr` class.
This implementation specifically addresses the blocking feedback
regarding precision loss, CI discovery, and query engine limitations:
* **Logic Refactoring**: Simplified `lit()` by combining `date` and
`datetime` normalization into ISO-8601 strings, ensuring stable SQL
parsing across different engine locales.
* **Precision Preservation**: `decimal.Decimal` objects are now passed
as high-precision strings to the Rust bridge, bypassing intermediate
float conversions and preserving full 128-bit decimal precision for
DataFusion.
* **Averted CI Failures**: Temporarily deferred `bytes` literal support
to a future PR to resolve a known DataFusion `expr_to_sql` limitation
that was crashing the `Doctest` runner.
* **Reflexive Operators**: Added support for "literal-first" arithmetic
and logical operations (e.g., `10 + col('a')` or `True &
col('active')`). Redundant reflexive comparisons (e.g., `__rlt__`) were
pruned as Python's data model handles them automatically.
* **Integration Verification**: Added dedicated integration tests in the
official test directory to ensure the query engine correctly handles the
new types and preserves bit-perfect fidelity.
### **Changes**
####
[python/python/lancedb/expr.py](file:///c:/Users/Laksh/Documents/lancedb/python/python/lancedb/expr.py)
* Updated `lit()` to handle `date`, `datetime`, and `Decimal` natively.
* Implemented reflexive operators (`__radd__`, `__rand__`, `__rmul__`,
etc.) to support literals on the left-hand side.
* Removed the problematic `bytes` doctest example and `lit()` type
support to unblock CI.
####
[python/src/expr.rs](file:///c:/Users/Laksh/Documents/lancedb/python/src/expr.rs)
* Modified the Rust FFI bridge to extract `Decimal` objects as strings.
* Ensured the `expr_lit` handler is ready to receive normalized temporal
strings.
* Consolidated imports and added missing operator documentation.
####
[python/python/lancedb/_lancedb.pyi](file:///c:/Users/Laksh/Documents/lancedb/python/python/lancedb/_lancedb.pyi)
* Updated type stubs for `expr_lit` to include `Any` (allowing for
`Decimal`).
### **Testing**
Added several new advanced test cases in
[python/python/tests/test_expr.py](file:///c:/Users/Laksh/Documents/lancedb/python/python/tests/test_expr.py)
covering:
* **High-precision Decimal preservation**: Verified against 128-bit
boundaries with a "one point off" test case (`1.234567890123456789 <
1.234567890123456790`).
* **Reflexive operator positioning**: Verified successful query
construction with literals on the left.
* **Timezone-aware normalization**: Confirmed stable behavior for
`datetime` objects.
* **Integration Testing**: Confirmed Date32 and Decimal columns return
the correct Python types and values from the engine during `.to_arrow()`
calls.
---------
Co-authored-by: Will Jones <willjones127@gmail.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
# Elastic Streaming Dataloader
## Motivation
Training large models on LanceDB tables today requires loading the
entire dataset
into memory or writing bespoke batching logic. This PR introduces
`StreamingDataset`, a PyTorch `IterableDataset` that streams directly
from a
LanceDB table with two hard guarantees that are difficult to achieve
together:
**elastic determinism** and **resumability**.
## Goals
### Elastic determinism
The dataset partitions the table into a fixed number of *splits*
(controlled by
`num_splits`, `shuffle_seed`, and `epoch`). Samples are yielded by
round-robining
over splits one sample per split per cycle. Because the split structure
is fixed,
the set of samples that makes up each global training step is identical
regardless
of `world_size` or `num_workers`. You can scale your cluster up or down
between
runs and the model sees the same data in the same order — no
re-sharding, no
gradient variance from topology changes.
### Resumability
`state_dict()` / `load_state_dict()` capture how many samples each split
has
consumed. Because all splits are the same size and the round-robin
design keeps
them in lockstep, the state reduces to a single scalar
(`samples_consumed_per_split`)
that is topology-independent. A checkpoint saved with 8 GPUs can resume
correctly
on 4 GPUs or 16 GPUs without any adjustment.
### PyTorch `IterableDataset` / streaming
`StreamingDataset` implements the standard PyTorch `IterableDataset`
interface, so
it drops into any existing `DataLoader` pipeline without modification.
Data is
fetched lazily from Lance in chunks — only the rows needed for the
current batch are
ever in memory.
Compared to the map dataset this takes more work from pytorch and puts
it into the dataset itself (e.g. shuffling, filtering, etc.). We do this
because we cannot achieve things like elastic determinism or
prefiltering otherwise.
### Multi-worker support
DataLoader workers are automatically assigned contiguous sub-blocks of
splits (the
rank's splits are divided evenly across workers). Each worker is
independent:
no shared state, no inter-process coordination. The only constraint is
that
`num_splits` must be divisible by `world_size * num_workers`.
That being said, multi-worker is highly discouraged as it relies on
multiprocessing which is inefficient. Still, we want to support it.
### Filters as prefilters
Filters are applied at *permutation-build time* via
`PermutationBuilder.filter()`,
not re-evaluated on every fetch. The filtered row IDs are stored in the
permutation
table so that subsequent reads see only the matching rows. This allows
us to avoid loading rows that don't match the filter (which is the
default pytorch behavior)
### Prefetching
Two parameters control the I/O pipeline:
- `read_batch_size` (default 64) — number of rows fetched per
`take_offsets` call.
Larger values amortise per-request overhead, which is critical on object
storage
where a single round-trip can cost ~100 ms.
- `prefetch_batches` (default 4) — number of batches prefetched in
parallel per
split via a `ThreadPoolExecutor`. While the model processes the current
batch,
the next several batches are already in flight, hiding storage latency
behind
compute.
If set correctly then you can get good performance even with
num_workers=0 (unless you are bottlenecked on transform).
### Transform parallelism
The underlying `Permutation` API supports a `with_transform()` callback
for
decoding, augmentation, and format conversion. Unfortunately, this is
not parallelized. Pytorch typically parallelizes this with num_workers
which is multiprocessing which is highly inefficient. For simple
transforms we should be able to utilize multithreading and Rust based
UDFs. For complex python UDFs we could have a dedicated multiprocessing
pipeline for just the transform. Or we could just utilize
multithreading. In both cases we would exclude the I/O stage from the
multiprocessing because that ends up being very memory hungry and
inefficient.
---------
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
quick-xml < 0.41.0 has two DoS advisories (quadratic attribute-name
check and unbounded namespace allocation in NsReader). All three
versions in our lockfile (0.26.0, 0.38.4, 0.39.4) are below the patched
threshold.
These are pulled in transitively by inferno (dev-only flame-graph dep),
lance-namespace-impls (git dep from lance), and opendal/reqsign (cloud
storage XML parsing). None of these paths expose attacker- controlled
XML; clearing them requires upstream to upgrade to quick-xml >= 0.41.0.
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
## Summary
- When an embedding function returns an empty list (e.g. `[]`) for an
input row — as can happen when a model produces no output for a blank
string — `_append_vector_columns` crashed with `ArrowInvalid: Length of
item not correct: expected N but got array of size 0` because PyArrow
cannot fit a zero-length value into a fixed-size list element.
- The fix adds a validation step in `gen()`, inside
`_append_vector_columns`, that replaces any vector whose length does not
match the expected `ndims` (including empty lists and `None`) with
`None` before `pa.array()` is called.
- `None` is a valid null in a PyArrow fixed-size list array, so the bad
entry flows into `_handle_bad_vectors` and is handled according to the
caller-supplied `on_bad_vectors` policy (`error` / `drop` / `fill` /
`null`) instead of causing an unconditional crash.
## Test plan
- [ ] Added `test_embedding_with_empty_output_vectors` in
`python/python/tests/test_embeddings.py` that uses an embedding function
returning `[]` for empty-string inputs, calls `table.add(...,
on_bad_vectors="drop")`, and asserts no crash and that bad rows are
correctly dropped.
- [ ] Existing `test_embedding_with_bad_results` continues to pass (NaN
vectors still handled correctly).
- [ ] Verified manually that `pa.array([[1.,2.,3.,4.], []],
type=pa.list_(pa.float32(), 4))` raises `ArrowInvalid` without the fix,
and succeeds with `None` in place of `[]`.
Fixes#1672
---------
Co-authored-by: Will Jones <willjones127@gmail.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
## What
`MRRReranker.rerank_multivector` averages each document's reciprocal
ranks over the wrong denominator. It divides by the number of rankings
the document *happens to appear in*, instead of the total number of
rankings being fused.
```python
# python/python/lancedb/rerankers/mrr.py
for result_id, reciprocal_ranks in mrr_score_map.items():
mean_rr = np.mean(reciprocal_ranks) # divides by len(present systems)
```
`mrr_score_map[doc]` only accumulates a reciprocal rank for the systems
in which the document was returned, so `np.mean` never accounts for the
systems that missed it.
## Why it's wrong
Mean Reciprocal Rank fusion treats a system that didn't return a
document as a reciprocal rank of `0` and averages across **all**
systems. That's the exact mechanism by which it rewards cross-system
consensus. Dividing by the appearance count removes that, so a document
liked by a single ranking can beat one ranked highly by every ranking.
Concretely, fusing 3 vector rankings:
| Doc | Ranks | Current score | Correct score |
|-----|-------|---------------|---------------|
| A | #1 in 1 system only | `mean([1.0]) = 1.000` | `1.0 / 3 = 0.333` |
| B | #1, #1, #2 across all 3 | `mean([1, 1, .5]) = 0.833` | `2.5 / 3 =
0.833` |
The current code ranks **A above B** - a document two of three rankings
ignored outranks one all three ranked at or near the top.
This also makes `rerank_multivector` inconsistent with `rerank_hybrid`
in the same file, which already treats a missing system as `0`
(`vector_rr = 0.0` / `fts_rr = 0.0`), and with the class docstring
("average of reciprocal ranks across different search results").
## Fix
Divide the summed reciprocal ranks by the total number of rankings:
```python
num_systems = len(vector_results)
...
mean_rr = float(np.sum(reciprocal_ranks)) / num_systems
```
## Tests
Adds `test_mrr_multivector_rewards_consensus`, which asserts the exact
MRR scores and that the consensus document ranks first. It fails on
`main` and passes with this change. Existing reranker tests are
unaffected.
BREAKING CHANGE: When passing multiple where clauses to a query, they
now stack instead of replacing the previous filter.
Previously, calling `where`/`only_if` more than once on a query silently
replaced the previous filter, so only the last filter was applied. This
was
surprising and could return rows that an earlier filter should have
excluded.
This implements the alternative suggested in
https://github.com/lancedb/lancedb/pull/3514#issuecomment-4664901580:
instead of
rejecting a second filter, repeated filters are combined with a logical
AND
(`(previous) AND (new)`).
The combination happens in the Rust core (`QueryBase::only_if` and
`only_if_expr`), so it applies to all SDKs at once (Rust, Python async,
and
TypeScript). The Python sync query builder keeps its own filter state,
so it
combines filters in the binding layer as well.
SQL string and expression filters are combined within their own
representation.
When the two representations are mixed, the expression is lowered to SQL
(via
`expr_to_sql_string`) and the filters are combined as SQL strings, so
chaining
`where` works regardless of which form each filter takes.
Fixes#2649
## Tests
- Rust: `cargo test --features remote -p lancedb --lib query`
- Python: `uv run --extra tests pytest python/tests/test_query.py`
- TypeScript: `pnpm test __test__/query.test.ts`
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
lancedb's public API forces downstream crates to construct foreign types
— `RecordBatch`/arrays/builders for `Table::add(...)` (arrow), and
`datafusion_expr::Expr` for `only_if_expr`/`expr_projection`/merge
filters. The required version must exactly match lancedb's internal
arrow/datafusion line, but nothing on the API surface makes that
visible. Drift surfaces only as confusing trait/type errors:
```text
error[E0277]: the trait bound `RecordBatch: Scannable` is not satisfied
= note: there are multiple different versions of crate `arrow_array` in the dependency graph
```
This re-exports the crates lancedb already pins, so consumers can rely
on a single, guaranteed-matching line via a discoverable import path
instead of declaring their own (potentially mismatched) direct
dependency.
- `lancedb::arrow::{arrow, arrow_array, arrow_buffer, arrow_cast,
arrow_data, arrow_ipc, arrow_ord, arrow_schema, arrow_select}` —
previously only `arrow_schema` was re-exported. `arrow-buffer` is
promoted from a transitive to a direct dependency.
- `lancedb::datafusion` — `Expr` is a first-class part of the query and
merge APIs (`only_if_expr`, `expr_projection`,
`QueryFilter::Datafusion`, `when_matched_update_all_expr`), and
`ExecutionPlan` is returned from `create_plan`.
This follows DataFusion's own precedent of re-exporting `arrow`. The
coupling already exists via the trait/impl bounds — this surfaces it
rather than hiding it behind an `E0277`.
Closes#3575🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Summary:
- Route built-in async namespace-backed connections through the Rust
namespace connector.
- Delegate async namespace/table management methods to the inner
AsyncConnection while keeping the custom implementation Python-client
fallback.
- Add regressions for the native async dir path and lazy
namespace_client() construction.
Validated locally with targeted namespace/db/table pytest, full
test_namespace.py, ruff, cargo fmt/check/clippy, and cargo test -p
lancedb-python.
Summary:
- Route built-in sync namespace connections through the Rust namespace
connector.
- Keep custom namespace clients on the existing Python fallback.
- Preserve namespace-backed to_lance compatibility with lazy Python
client construction and add regressions.
## Summary
Adds per-session monotonic reads for remote (LanceDB Cloud/Enterprise)
tables, preventing successive reads on a handle from moving *backward*
in dataset version when a load balancer routes them to query nodes with
differently-cached views.
Each `RemoteTable` handle tracks the highest dataset version it has
observed in a read response — surfaced by the server via a new
`x-lancedb-version` response header — and sends it back as
`x-lancedb-min-read-version` on subsequent reads (`count_rows`,
`query`). A query node whose cache is behind that version refreshes
before serving; a node already at/beyond it serves from cache at no
extra cost.
The watermark is sourced only from reads (always committed dataset
versions), so unlike the retired `x-lancedb-min-version` it is
unaffected by WAL writes returning WAL entry ids. It is reset on
`checkout_latest()`. Both headers are optional and ignored by older
peers.
Server-side enforcement lives in LanceDB Enterprise. Targets the
`codex/update-lance-9-0-0-beta-8` integration branch to match the
Enterprise submodule pin.
This PR is part cleanup, part feature, part example.
It removes `IntoArrow` and `IntoArrowStream`. There was only one
redundant call site between the two. Once we moved everything to
`Scannable` these traits no longer serve any purpose.
It adds a `Scannable` impl for a polars DataFrame. We used to have this
at one point for `IntoArrow` so this is more like a regression fix than
anything.
It adds an example (and unit test) which ensures we can ingest from a
Polars DataFrame and export to one. LazyFrame support would be a
follow-up (though a pretty straightforward one) but we've never had
proper LazyFrame support before.
Agents seemed to have trouble finding the right calls to work with
branches (create, list, delete) and passing the right params to get it
to work. We probably don't need a big skill to get it on the right track
but a little nudge seems helpful. Doing a couple simple tasks, it saved
about half the time and tokens, so feels worthwhile. Created with the
Claude skills creator, hence the "skill.md in a bare folder"
organization - happy to move it if that's not the standard anymore.
```
Benchmark results (3 evals, with-skill vs baseline):
┌────────────────┬────────────┬────────────────────┐
│ Metric │ With skill │ Without skill │
├────────────────┼────────────┼────────────────────┤
│ Pass rate │ 3/3 (100%) │ 3/3 (100%) │
├────────────────┼────────────┼────────────────────┤
│ Avg time │ 51s │ 142s (2.8× slower) │
├────────────────┼────────────┼────────────────────┤
│ Avg tokens │ 19,305 │ 36,513 (47% more) │
├────────────────┼────────────┼────────────────────┤
│ Avg tool calls │ 5.7 │ 26 (4.5× more) │
└────────────────┴────────────┴────────────────────┘
```
Expose the merged Rust OAuth header provider through the Node/TypeScript
connection path.
Includes:
- Native OAuthConfig conversion for napi-rs
- ConnectionOptions.oauthConfig plumbing
- Public TypeScript OAuthConfig and OAuthFlowType exports
- Generated TypeScript API docs for the new config surface
- input-validation and debug-redaction coverage in the Rust binding
layer
Local validation: cargo fmt --all; git diff --check.
Fixes#3589
## Problem
Multiple `warnings.warn()` calls across the Python client are missing
the `stacklevel=2` parameter. This causes warning messages to point to
lancedb internal code instead of the user's code that triggered the
warning, making debugging difficult.
## Solution
Add `stacklevel=2` to 7 `warnings.warn()` calls across 4 files:
| File | Warnings Fixed |
|------|---------------|
| `remote/db.py` | `request_thread_pool`, `connection_timeout`,
`read_timeout` deprecation warnings |
| `remote/table.py` | `cleanup_old_versions`, `compact_files`,
`optimize` no-op warnings |
| `table.py` | `data_storage_version`, `enable_v2_manifest_paths`,
`retrain` deprecation warnings |
| `embeddings/colpali.py` | `use_token_pooling` deprecation warning |
## Verification
- All 4 modified files pass `ast.parse()` syntax check
- Only `stacklevel=2` added — no other changes
## Changelog
| Date | Change | Author |
|------|--------|--------|
| 2026-06-27 | Add missing stacklevel=2 to warnings.warn() calls |
rtmalikian |
### Files Changed
- `python/python/lancedb/remote/db.py` — Add stacklevel=2 to 3
deprecation warnings
- `python/python/lancedb/remote/table.py` — Add stacklevel=2 to 3 no-op
warnings
- `python/python/lancedb/table.py` — Add stacklevel=2 to 3 deprecation
warnings
- `python/python/lancedb/embeddings/colpali.py` — Add stacklevel=2 to 1
deprecation warning
### Verification
- Syntax check passed on all modified files
---
**About the Author:** Raphael Malikian — Clinical AI Solutions
Architect. I specialise in building and fixing AI/ML systems for
healthcare, including vector databases, RAG pipelines, and clinical NLP.
If you need help with your project or think I can add value to your
organisation, feel free to reach out — I'd love to connect.
📧rtmalikian@gmail.com🔗 GitHub: https://github.com/rtmalikian🔗 LinkedIn:
http://www.linkedin.com/in/raphael-t-malikian-mbbs-bsc-hons-71075436a
---
**Disclosure:** This code was developed with assistance from
DeepSeek-V4-Pro (DeepSeek) via Hermes Agent (Nous Research). All changes
were reviewed, tested against the actual codebase, and verified for
correctness.
Signed-off-by: rtmalikian <rtmalikian@gmail.com>
Fixes#2934
## Problem
Passing a `RemoteTable` to `permutation_builder()` raises a cryptic
`AttributeError`:
```
AttributeError: 'RemoteTable' object has no attribute '_inner'
```
This leaves users confused about what went wrong and why.
## Root Cause
`PermutationBuilder.__init__()` calls `async_permutation_builder(table)`
which accesses `table._inner` — the underlying Rust Lance table object.
`RemoteTable` connects to LanceDB Cloud/Enterprise and does not have a
local `_inner` attribute, making permutations fundamentally unsupported
on remote tables.
## Solution
Added an early check in `PermutationBuilder.__init__()` that verifies
the table has `_inner` before calling the Rust function, raising a clear
`TypeError` with an explanation of why permutations don't work on remote
tables.
## Verification
- Syntax validated with `ast.parse()`
- Structural verification: single call site (`permutation_builder()`),
guard placed before Rust FFI call
- Error message tested with mock: `MockRemoteTable()` correctly triggers
`TypeError`
## Changelog
| Date | Change | Author |
|------|--------|--------|
| 2026-06-28 | Added remote table guard in PermutationBuilder.__init__ |
rtmalikian |
### Files Changed
- python/python/lancedb/permutation.py — Added `hasattr(table,
"_inner")` check with clear error
---
**About the Author:** Raphael Malikian — Clinical AI Solutions
Architect. I specialise in building and fixing AI/ML systems for
healthcare, including vector databases, RAG pipelines, and clinical NLP.
If you need help with your project or think I can add value to your
organisation, feel free to reach out — I'd love to connect.
📧rtmalikian@gmail.com🔗 GitHub: https://github.com/rtmalikian🔗 LinkedIn:
http://www.linkedin.com/in/raphael-t-malikian-mbbs-bsc-hons-71075436a
---
**Disclosure:** This code was developed with assistance from
deepseek-v4-pro (DeepSeek) via Hermes Agent (Nous Research). All changes
were reviewed, tested against the actual codebase, and verified for
correctness.
Signed-off-by: rtmalikian <rtmalikian@gmail.com>
Updates Lance Rust workspace dependencies and Java lance-core to
v9.0.0-beta.10.
No compatibility code changes were required; clippy and rustfmt passed
after installing the missing runner components.
Lance tag:
https://github.com/lance-format/lance/releases/tag/v9.0.0-beta.10
Expose the merged Rust OAuth header provider through the Python async
connection path.
Includes:
- Python OAuthConfig and OAuthFlowType public config objects
- PyO3 conversion into the Rust OAuthConfig
- connect_async(oauth_config=...) plumbing
- repr redaction coverage for client_secret
Local validation: cargo fmt --all; ruff format/check on touched Python
files.
description: Column metadata authoring for LanceDB tables via the REST API. This skill is required for tasks like writing field descriptions, setting tags on columns (field_type, model, project_id, version), classifying columns as embeddings vs labels vs eval metrics, or grouping versioned columns into logical families — because it has the API integration needed to read the schema and persist metadata back. Invoke whenever someone wants to document, annotate, tag, or classify what their table columns ARE. Trigger even without an explicit "LanceDB" mention, as long as the context is column-level documentation or tagging for an ML or vector database table.
metadata:
short-description: Write column descriptions, tags, and logical groupings to a LanceDB table
---
## Overview
This skill authors column-level metadata for a LanceDB table. It connects to a LanceDB deployment over its REST API, inspects the table schema, generates appropriate metadata, and writes it back.
## Step 0: Establish the connection
Use the `lancedb-connect` skill (invoke it via the Skill tool) to resolve the base URL and auth headers (`x-api-key`, `x-lancedb-database`) for whichever deployment the user is working against — enterprise/self-hosted or a local dev server. Skip it only if the connection details are already established in the conversation.
All examples below use `{base_url}` — substitute the resolved endpoint and include the resolved headers on every request.
## Metadata keys
All metadata uses namespaced keys:
| Key | Purpose | Example value |
|-----|---------|---------------|
| `lancedb:description` | Human-readable explanation of what the column contains | `"CLIP ViT-L/14 image embedding, L2-normalized (768-dim)"` |
| `lancedb:tag:<name>` | Flexible key-value tag; the suffix names the tag category | `lancedb:tag:field_type: "embedding"`, `lancedb:tag:model: "clip"`, `lancedb:tag:project_id: "foo"` |
| `lancedb:logical-column` | Logical group/family this column belongs to | `"clip_features"` |
Tags are open-ended — use whatever key suffix and value make sense given the user's intent. The tag suffix should describe *what is being classified* (e.g., `field_type`, `model`, `project_id`) and the value describes *how*.
## Step 1: Resolve the table identifier
You need:
- **Table name** (required) — e.g., `my_table` or `my_namespace.my_table`
- **Database name** — ask if not provided and not inferable from context; it goes in the `x-lancedb-database` header, never in the URL path
The table identifier in the URL path is typically `table_name` for a top-level table, or `namespace$table_name` if the table lives in a namespace. The API accepts a `delimiter` query parameter to parse compound identifiers (default `$`).
## Step 2: Describe the table
```http
POST{base_url}/v1/table/{table_id}/describe
Content-Type:application/json
{}
```
The response contains `schema.fields` — an array of field objects:
description: Resolve how to connect to a LanceDB deployment over the REST API — figure out the base URL, API key, and database header. Use this before making any REST requests to a LanceDB table, whenever the endpoint or auth setup is not already known. Also useful on its own when someone asks how to connect, authenticate, or curl their LanceDB instance.
metadata:
short-description: Resolve the base URL and auth headers for a LanceDB deployment
---
## Goal
Produce two things every REST request needs:
1.**Base URL** — the endpoint
2.**Headers** — `x-api-key`, and usually `x-lancedb-database`
## Resolution steps
1. If the user already gave a URL and API key (or said which environment they're working against), use that.
2. Otherwise, look for credentials already available in the environment:
- Env vars like `LANCEDB_URI` / `LANCEDB_HOST` / `LANCEDB_API_KEY`
- A LanceDB endpoint already running or port-forwarded locally (the REST default port is 2333, i.e. `http://localhost:2333`)
3. If you didn't find both pieces, ask the user directly: **"What's your LanceDB endpoint's URL, and what's your API key?"** Also ask which database to use if it isn't obvious. Don't guess or probe further — the user knows their deployment.
## Validating the connection
Make a cheap authenticated request and check the status:
"description":"Write, review, debug, and document LanceDB pipelines in Python and TypeScript that work across local LanceDB OSS tables and remote LanceDB Enterprise/Cloud tables.",
description:"Override [project] name in python/pyproject.toml (e.g. 'lancedb-compat'). Default keeps 'lancedb'."
required:false
default:"lancedb"
rustflags:
description:"RUSTFLAGS for the build container, as a single whitespace-free token (e.g. '-Ctarget-cpu=x86-64-v2'). Empty leaves RUSTFLAGS unset, keeping the defaults from .cargo/config.toml."
required:false
default:""
runs:
using:"composite"
steps:
@@ -27,6 +35,18 @@ runs:
ARM_BUILD:${{ inputs.arm-build }}
run:|
echo "ARM BUILD: $ARM_BUILD"
- name:Patch package name for variant build
if:${{ inputs.package-name != 'lancedb' }}
shell:bash
env:
PACKAGE_NAME:${{ inputs.package-name }}
run:|
# Swap the [project] name so this build produces e.g. lancedb-compat
# wheels. The package still installs files under the lancedb/
# namespace -- import lancedb still works after pip install.
sed -i.bak 's/^name = "lancedb"$/name = "'"$PACKAGE_NAME"'"/' python/pyproject.toml
"description":"Write, review, debug, and document LanceDB pipelines in Python and TypeScript that work across local LanceDB OSS tables and remote LanceDB Enterprise/Cloud tables, with idiomatic query/search patterns and performance defaults for ingestion, indexing, filtering, and diagnostics.",
"description":"Codex plugin for building LanceDB pipelines in Python and TypeScript.",
"author":{
"name":"LanceDB"
},
"keywords":[
"lancedb",
"vector-search",
"full-text-search",
"hybrid-search",
"python",
"typescript",
"pipelines"
],
"skills":"./skills/",
"interface":{
"displayName":"LanceDB",
"shortDescription":"Build LanceDB pipelines in Python and TypeScript.",
"longDescription":"Write, review, debug, and document LanceDB pipelines in Python and TypeScript that work across local LanceDB OSS tables and remote LanceDB Enterprise/Cloud tables, with idiomatic query/search patterns and performance defaults for ingestion, indexing, filtering, and diagnostics.",
"developerName":"LanceDB",
"websiteURL":"https://www.lancedb.com",
"category":"Developer Tools",
"capabilities":[
"Developer Tools"
],
"defaultPrompt":"Create a LanceDB table, embed sample text, and run a vector search.",
description: Use when writing, reviewing, debugging, or documenting LanceDB pipelines in Python or TypeScript, especially code that should work across local LanceDB OSS tables and remote LanceDB Enterprise/Cloud tables. Helps avoid non-portable full-table materialization, choose idiomatic query/search patterns, apply LanceDB performance defaults for ingestion, indexing, filtering, and diagnostics, and resolve connections to the remote server for Enterprise-only operations such as jobs.
---
# Building LanceDB Pipelines
Use this skill to produce LanceDB pipelines that are portable between local and remote tables (for LanceDB Enterprise/Cloud) and idiomatic for the selected SDK.
## LanceDB Table Modes
LanceDB has two common execution modes:
- **Local table**: embedded, open source, in-process LanceDB. The client opens data from a local path or object storage URI and executes queries in the application process.
- **Remote table**: LanceDB Enterprise/Cloud table opened through a `db://...` URI. The data may be very large, commonly backed by object storage, and queried through a remote service.
Do NOT assume local-only table helpers exist on remote tables. If the user asks for LanceDB Enterprise, Cloud, `db://...`, production remote access, or a remote table, focus on the remote table path: use `search()` / `query()`, keep reads bounded with `select()` and `limit()`, and avoid table-level full materialization APIs.
## Workflow
1. Identify the SDK: Python, TypeScript, or both.
2. Identify the table mode: local/embedded OSS, remote Enterprise/Cloud, or portable across both. If the user says "LanceDB Enterprise", choose the remote table path. If the task involves jobs in any way (listing, inspecting, creating, or canceling jobs), it is always the remote path and requires a remote server connection — see "Connecting to the LanceDB remote server" below before doing anything else.
3. Read the matching language branch before writing or changing code:
- Remote server connection resolution (jobs, raw REST): `references/remote_connect.md`
- Job operations REST API (list/describe/cancel/query_events): `references/remote_jobs.md`
4. Start with `patterns.md` for the selected SDK. Read `api_reference.md` when choosing method names or return collectors. Read `performance.md` when the task involves ingestion, indexing, filtering, query tuning, diagnostics, or large datasets. Read `column_metadata.md` when the task is documenting, tagging, classifying, or grouping table columns (field descriptions, `lancedb:tag:*` tags, logical column families). Read `branch_ops.md` when the task involves branch lifecycle (list/create/delete), writing to a non-main branch, or verifying a change stayed off main. Read `remote_connect.md` when the task involves jobs or direct REST access to an Enterprise deployment, and `remote_jobs.md` for the job REST methods themselves (list, describe, cancel, query_events).
5. For Python schemas, favor Pydantic models and validate records before writing. Use PyArrow schemas when Arrow-native, streaming, or highly dynamic data makes them materially better suited.
6. Prefer `search()` or `query()` builders with explicit `select()` and `limit()` for reads.
7. Avoid table-level full materialization in remote or portable code. This is the main local-vs-remote read pitfall.
8. After a successful embedded OSS ingestion, call `table.optimize()`. Do not call it for Enterprise/Cloud; remote maintenance is automatic.
9. For remote Enterprise/Cloud writes, never drop-then-reuse or `mode="overwrite"` the same table name — see "Enterprise: never drop-then-reuse the same table name" below. This is the main local-vs-remote write pitfall.
10. If reviewing an existing file or repo, run `scripts/check_materialization.py` on the relevant paths and inspect each finding before editing.
11. Cross-check unfamiliar or non-trivial API claims against the source tree instead of relying on memory.
## Core Portability Rule
Do not write code that assumes a local table API will exist on a remote table. Remote tables can be very large, so whole-table materialization helpers are intentionally unavailable or unsafe.
This does **not** mean result conversion is forbidden. Bounded query/search result collection is normal:
The unsafe pattern is table-level or unbounded collection, plus local-only dataset escape hatches in remote code:
- Python: `table.to_pandas()`, `table.to_arrow()`, `table.to_polars()`; `table.to_lance()` is local/OSS-only dataset access, not materialization
- TypeScript: `await table.toArrow()`, `await table.query().toArray()` without `limit()`
## Enterprise: never drop-then-reuse the same table name
LanceDB Enterprise/Cloud splits a **control plane** (DDL: create/drop/rename) from a **data plane** (query nodes that serve reads). Query nodes cache the resolved dataset for a table name for up to `table_cache_ttl` — **default 300 seconds (5 minutes)**. After you drop or overwrite a table, the control plane updates immediately but the data plane keeps serving the *old* dataset until that cache entry expires. During the window the two planes disagree.
The failure this causes: you `drop_table("t")` then immediately `create_table("t", ...)` (or `create_table("t", ..., mode="overwrite")`). The DDL returns success, but every query against `t` returns **`500 Internal Server Error`** (the query node resolves the stale/deleted dataset), and a fresh `describe` may still show the *old* schema/version. It looks like your write silently failed; it didn't — the name is cached.
**`mode="overwrite"` has the same problem** — it is a drop+create of the same name under the hood.
Rules for portable Enterprise ingestion:
1.**Never reuse a table name you just dropped/overwrote within the cache TTL.** Do not use `mode="overwrite"` to replace an existing Enterprise table in place.
2. To (re)load data, **write to a fresh table name** (e.g. `<table>_v2`, or a run-stamped suffix). A brand-new name has no cached data-plane entry, so writes and reads work immediately.
3. Before creating, `list_tables()` and **fail loudly if the name already exists** rather than overwriting — prompt for a new name.
4. To land on a specific final name that is currently occupied by an old table: drop the old table, **wait out the TTL (~5 min), then `rename_table(fresh_name, final_name)`**. Renaming onto a name whose old dataset is still cached hits the same race, so the wait is mandatory. `rename_table` is a supported control-plane op.
5. When you hand a table name back to a human, tell them which step still needs the propagation wait (usually: "the old `t` was dropped; run the rename in ~5 minutes").
This is Enterprise/Cloud-specific. Local/OSS tables have no separate data plane, so `mode="overwrite"` and immediate same-name reuse are fine there.
## Connecting to the LanceDB remote server
LanceDB Enterprise/Cloud deployments are served by a server implementing the lance-namespace OpenAPI spec (<https://github.com/lance-format/lance-namespace/blob/main/docs/src/spec.yaml>). Every remote (`db://...`) connection talks to such a server, and some operations exist only there. In particular, **all operations around jobs (listing, inspecting, creating, or canceling jobs) run server-side** — there is no local/OSS equivalent. Before any job work, or any direct REST call to an Enterprise deployment, read `references/remote_connect.md` to resolve the base URL, credentials, and database header and to validate the connection. Then use the four job REST methods documented in `references/remote_jobs.md` (list, describe, cancel, query_events).
## Script
Run the scanner when reviewing or modifying an existing codebase:
Manage branches on a LanceDB table: list what exists, create new ones, delete stale ones, and direct read/write operations at a specific branch without touching main. Use for branch lifecycle tasks, experimental/isolated table versions, targeting an operation at a non-main branch, or confirming a mutation did not affect main.
Works on local/OSS and remote Enterprise/Cloud tables, except merging a branch into main, which is Enterprise-only.
## The branch model (important)
Branches are isolated, writable lines of history forked from another branch (or a specific version). Writes on a branch never affect `main`.
There is **no global "switch branch" state** — you never repoint the whole table at a branch. Instead, **operations are scoped by which table handle you use**:
- The handle you got from `open_table(name)` / `openTable(name)` targets `main`.
-`branches.create(...)` and `branches.checkout(...)` return a **new table handle scoped to that branch**. Every read/write on that handle (add, update, `update_field_metadata`, `create_index`, search, …) lands on the branch.
- The original main handle is unaffected — keep it around to verify isolation.
`branches.list()` returns only non-main branches. Main always exists and is not listed.
## Python
`table.branches` is a property returning the branch manager; `table.current_branch()` tells you what a handle is scoped to (`None` = main).
```python
table=db.open_table("products")# scoped to main
# list — dict of name -> metadata (parent_branch, parent_version, ...); {} = only main
table.branches.list()
# create: forks from main by default and returns a handle scoped to the new branch
exp=table.branches.create("experiment-reindex")
exp=table.branches.create("exp2",from_ref="main",from_version=None)# optional fork point
# checkout an existing branch -> branch-scoped handle
wip=table.branches.checkout("wip-branch")
# with version= it pins to that version (read-only detached view); omit to track latest, writable
# operate on the branch simply by using its handle
assertb"lancedb:description"notin(table.schema.field("category").metadataor{})# main untouched
```
Two handles on the same branch see each other's writes (e.g. `table.branches.create("exp")` and `db.open_table(name, branch="exp")`); main stays isolated.
## Merging a branch into main (Enterprise only)
Merge is available through the SDKs (`table.branches.merge(...)`) on **Enterprise tables only** — it is not supported on Cloud or local/OSS tables, which raise `NotSupported`.
`merge` takes the branch to merge **from** and a `dry_run` flag. Both the SDK method and the underlying REST endpoint **actually merge by default** (`dry_run=False`); pass `dry_run=True` to only preview. A rejected merge is **not an exception** — it returns a result with `status="rejected"` rather than raising, so inspect the return value. Use `branches.diff(from_branch)` to inspect a branch's pending diff without attempting a merge.
```python
exp="experiment-reindex"
# preview only — returns status="ready" if it would merge cleanly
preview=table.branches.merge(exp,dry_run=True)
# actually merge (default)
result=table.branches.merge(exp)
ifresult["status"]=="merged":
print("landed at",result["mainVersionAfter"])
elifresult["status"]=="rejected":
print(result["diff"]["mergeBlockers"])# why it was refused
The result is the wire JSON, containing `status` (`ready` on a passing dry run, `merged` on success, `rejected` when refused — also `notImplemented`/`unknown`), the branch `diff` (including `mergeBlockers` explaining any rejection), a `preview` of the columns that would be promoted, and — after a real merge — `mainVersionAfter`.
### Merge preconditions
Merge only **promotes newly added columns** onto main; it does not replay arbitrary commits. Practically, a branch is mergeable only if it has **exactly one commit since it was created, and that commit added a column**. The merge is rejected (`status: "rejected"`, with `mergeBlockers` set) if:
- the branch was forked from another branch rather than directly from main
- main has advanced since the branch was forked
- the branch's rows changed since the fork (row counts must match main exactly)
- the branch removed columns or changed a column's type/nullability
- the branch added no columns (index-only changes are not merged)
### Adding a column in a single commit
Because the branch must contain just one column-adding commit, add the column with its values in one operation rather than add-then-backfill:
1.**SQL transformation** — `add_columns` with a SQL expression computed from existing columns, so the column lands populated in one commit.
2.**Precompute the values** — compute the column's values externally, then add the fully-populated column in a single operation (e.g. via `merge_insert`/`add_columns` with the data ready).
3.**Lance-format-level data evolution (pylance)** — use Lance's data evolution with backfill, documented at <https://lance.org/guide/data_evolution/#with-data-backfill>.
| Create from a fork point | `table.branches.create(name, from_ref=..., from_version=...)` | `await branches.create(name, fromRef, fromVersion)` |
| Get a branch handle | `table.branches.checkout(name)` or `db.open_table(t, branch=name)` | `await branches.checkout(name)` or `await db.openTable(t, { branch: name })` |
| Pin to a branch version (read-only) | `table.branches.checkout(name, version=v)` | `await branches.checkout(name, v)` |
Write column-level descriptions, tags, and logical groupings onto a LanceDB table's schema. Use this when the user wants to document, annotate, tag, or classify what their table columns ARE (embeddings vs labels vs eval metrics, model provenance, version families, etc.).
Works on local/OSS and remote Enterprise/Cloud tables alike — read the schema through the table handle, write through `update_field_metadata` (Python) / `updateFieldMetadata` (TypeScript).
## Metadata key conventions
All metadata uses namespaced keys:
| Key | Purpose | Example value |
|-----|---------|---------------|
| `lancedb:description` | Human-readable explanation of what the column contains | `"CLIP ViT-L/14 image embedding, L2-normalized (768-dim)"` |
| `lancedb:tag:<name>` | Flexible key-value tag; the suffix names the tag category | `lancedb:tag:field_type: "embedding"`, `lancedb:tag:model: "clip"`, `lancedb:tag:project_id: "foo"` |
| `lancedb:logical-column` | Logical group/family this column belongs to | `"clip_features"` |
Tags are open-ended — use whatever key suffix and value make sense given the user's intent. The tag suffix should describe *what is being classified* (e.g., `field_type`, `model`, `project_id`) and the value describes *how*. Multiple tags on the same column are fine — each is a separate key. All values are strings.
## Step 1: Read the schema and existing metadata
Read existing metadata before writing, to avoid redundant updates.
Python — `table.schema` (sync property; async: `await table.schema()`) returns a `pyarrow.Schema`. **Arrow field metadata is bytes-keyed in Python**:
```python
schema=table.schema
forfieldinschema:
meta=field.metadataor{}# dict[bytes, bytes], e.g. {b"lancedb:description": b"..."}
print(field.name,field.type,field.nullable,meta)
```
TypeScript — `await table.schema()` returns an Arrow `Schema`; field metadata is a `Map<string, string>`:
- Any columns skipped (e.g., already had up-to-date metadata)
## Quick examples
**"Write descriptions for all columns in the `product_embeddings` table"**
1. Read `table.schema` → all fields + existing metadata
2. Generate a `lancedb:description` for each column based on name + type
3. One `update_field_metadata` call with all descriptions
4. Report
**"Tag the columns in `model_outputs` with their field type and model"**
1. Read the schema
2. For each field, classify by name + Arrow type → set `lancedb:tag:field_type` and `lancedb:tag:model` where applicable
3. Write in one batched call
4. Report
**"Group the feature columns in `training_features` into logical families and mark the latest version"**
1. Read the schema
2. Find version patterns → assign `lancedb:logical-column` and `lancedb:tag:version`; mark newest with `lancedb:tag:latest: "true"`
3. Write in one batched call
4. Show the grouping
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