Jack Ye
f7ed6c6b93
The manual said the SQL dialect's function and type reference was out of scope. It is not: the engine is DataFusion 54 with its default function set registered, so the dialect is documented already and the useful thing is to say which version and point at it. The types are worth being concrete about rather than deferring. Lance's DataFusion table provider returns the dataset's Arrow schema directly — there is no SQL type layer over storage — so DataFusion's type reference describes Lance columns exactly, and a vector column is a FixedSizeList that behaves like one. Two consequences of that mapping are documented because they surprise people. The pseudo-columns the provider can append are real and typed — `_rowid`, `_rowaddr` and `_rowoffset` are nullable UInt64, and the nullability is a reused selection bitmap rather than a missing value, so a null there means nothing. And a blob column's Arrow type depends on how it is read: descriptions by default, binary on request, which changes the schema a query sees. `fts()` is recorded as what it is, a DataFusion TableProvider over the dataset. That explains the parts that otherwise look arbitrary: why it is a table function rather than a predicate, why every column of the table is available in its result, and why projections push into the scan.
LanceDB Documentation
LanceDB docs are available at docs.lancedb.com.
The SDK docs are built and deployed automatically by Github Actions
whenever a commit is pushed to the main branch. So it is possible for the docs to show
unreleased features.
Building the docs
Setup
- Install LanceDB Python. See setup in Python contributing guide.
Run
make developto install the Python package. - Install documentation dependencies. From LanceDB repo root:
pip install -r docs/requirements.txt
Preview the docs
cd docs
mkdocs serve
If you want to just generate the HTML files:
PYTHONPATH=. mkdocs build -f docs/mkdocs.yml
If successful, you should see a docs/site directory that you can verify locally.
Adding examples
To make sure examples are correct, we put examples in test files so they can be run as part of our test suites.
You can see the tests are at:
- Python:
python/python/tests/docs - Typescript:
nodejs/examples/
Checking python examples
cd python
pytest -vv python/tests/docs
Checking typescript examples
The examples depend on @lancedb/lancedb at file:../dist, so the package must be
built before running the tests. This uses pnpm; see the
Typescript contributing guide for the toolchain setup.
pushd nodejs
pnpm install
pnpm build
popd
Then you can run the examples by going to the nodejs/examples directory, which is a
separate pnpm package with its own lockfile:
pushd nodejs/examples
pnpm install
pnpm test
popd
API documentation
Python
The Python API documentation is organized based on the file docs/src/python/python.md.
We manually add entries there so we can control the organization of the reference page.
However, this means any new types must be manually added to the file. No additional
steps are needed to generate the API documentation.
Typescript
The typescript API documentation is generated from the typescript source code using typedoc.
When new APIs are added, you must manually re-run the typedoc command to update the API documentation. The new files should be checked into the repository.
pushd nodejs
# `pnpm docs` would invoke pnpm's built-in `docs` command, not the script.
pnpm run docs
popd