Files
lancedb/docs/web/quickstart.mdx
T
Xuanwo 1e5b6deee3 fix(python): support legacy blob query bytes (#4947)
## Summary

- Let local plain queries over row-addressable legacy v1 and v2 blob
columns use `blob_mode="bytes"` without importing `pylance` through
pandas, batch, or Arrow conversion.
- Preserve aliases, filters, ordering, limits, null and empty payloads,
empty result schemas, and the caller's `_rowid` choice.
- Build the hidden row-id query separately so reusing an async builder
for lazy reads or non-blob projections cannot retain an automatic
`_rowid`.
- Keep byte reads closed for blobs inside lists, remote or namespace
pushdown, and query shapes whose result rows cannot be matched back to
the source. Blob v2 lazy auto-row-id behavior is unchanged.

Fixes #4645

## Validation

- 26 focused Python tests passed with the test subprocess blocking all
`lance` imports. The persisted fixture writes and reopens a storage-v2.1
table, then covers sync and async pandas, batches, and Arrow conversion
plus async builder reuse.
- The existing unsupported vector and hybrid reranker regressions now
assert the current eligibility diagnostic, and the legacy table-level
Arrow regression now asserts successful bytes, schema, values, and
hidden row IDs. Both focused tests passed.
- The runtime receipt records no installed `pylance` distribution and no
importable `lance` module. The Python-only change was verified with an
existing compatible 0.42.0b9 extension; the relevant query and fetch
APIs are unchanged between that source and this 0.42.0b10 base.
- Ruff format and lint pass for every changed Python file.
2026-11-11 10:08:13 +08:00

398 lines
16 KiB
Plaintext

---
title: Quickstart
sidebarTitle: "Quickstart"
description: "Install LanceDB, create a table, and run your first vector search."
icon: rocket
---
import { PyConnect, TsConnect, RsConnect, PyConnectObjectStorage, TsConnectObjectStorage, RsConnectObjectStorage, PyConnectEnterprisePlaceholders, TsConnectEnterprisePlaceholders, RsConnectEnterprisePlaceholders } from '/snippets/connection.mdx';
import { PyQuickstartData, PyQuickstartCreateTable, PyQuickstartAddData, PyQuickstartCurateSample, PyQuickstartCurateDedupeSetup, PyQuickstartCurateDedupe, PyQuickstartCurateDedupeQuery, PyQuickstartFlattenStats, PyQuickstartAddFeature, PyQuickstartAddFeatureEnterprise, PyQuickstartMultimodalBytes, PyQuickstartTraining, TsQuickstartData, TsQuickstartCreateTable, TsQuickstartAddData, TsQuickstartVectorSearch1, TsQuickstartMultimodalBytes, RsQuickstartDefineStruct, RsQuickstartData, RsQuickstartCreateTable, RsQuickstartAddData, RsQuickstartVectorSearch1, RsQuickstartMultimodalBytes } from '/snippets/quickstart.mdx';
This quickstart uses LanceDB Embedded with a local database and works without an account or API key.
LanceDB Embedded runs in your application's process; your data can live on local disk or in object storage.
## 1\. Install LanceDB {#1-install-lancedb}
Choose your language. Python uses Pandas to display the search results. TypeScript needs Node.js 22.18 or later to run the `.mts` example directly.
<CodeGroup>
```bash Python (pip) icon="python"
pip install lancedb pandas
```
```bash Python (uv) icon="python"
uv venv
uv pip install lancedb pandas
```
```bash TypeScript icon="square-js"
npm install @lancedb/lancedb
```
```bash Rust icon="rust"
cargo init --name lancedb_quickstart
cargo add lancedb@0.31.0 --features polars,remote
cargo add tokio --features macros,rt-multi-thread
```
</CodeGroup>
Run the Rust commands in a new, empty directory. The `polars` feature provides DataFrame output; `remote` also lets this example connect to Enterprise.
<Accordion title="Python pre-release builds and older CPUs">
### Python pre-release builds {#python-pre-release-builds}
To pick up the latest features and bug fixes
before the next stable release, install a pre-release from LanceDB's Fury index.
<CodeGroup>
```bash Python (pip) icon="terminal"
pip install --pre --extra-index-url https://pypi.fury.io/lancedb/ lancedb
```
```bash Python (uv) icon="terminal"
uv venv
uv pip install --prerelease allow --index https://pypi.fury.io/lancedb/ lancedb
# To add to pyproject.toml, use:
uv add --prerelease allow --index https://pypi.fury.io/lancedb/ lancedb
```
</CodeGroup>
Most applications only need `lancedb`. Install the optional `pylance` extra and
include the Lance preview index only when building query engines or connectors,
calling format-level `lance` APIs directly, or converting plain-scan lazy blob
handles with `to_pandas()`. Legacy plain-scan byte conversions use LanceDB's
native path and do not require `pylance`:
<CodeGroup>
```bash Python (pip) icon="terminal"
pip install --pre \
--extra-index-url https://pypi.fury.io/lancedb/ \
--extra-index-url https://pypi.fury.io/lance-format/ \
"lancedb[pylance]"
```
```bash Python (uv) icon="terminal"
uv pip install --prerelease allow \
--index https://pypi.fury.io/lancedb/ \
--index https://pypi.fury.io/lance-format/ \
--index-strategy unsafe-best-match \
"lancedb[pylance]"
```
</CodeGroup>
The LanceDB preview index contains old `pylance` releases; current Lance previews
are published to the `lance-format` index. By default, uv only considers versions
from the first index containing a package, which can select an old `pylance` or
backtrack to an older LanceDB release. `unsafe-best-match` searches all configured
indexes, like pip; use it only with indexes you trust. Install the extra rather
than an unconstrained `pylance` so LanceDB's minimum supported version is enforced.
<Note>
Pre-release builds receive the same level of testing as stable releases, but their availability is not guaranteed
for more than 6 months after release. For real-world workloads, we recommend you use the latest stable release
as far as possible.
</Note>
### Older x86_64 CPUs {#older-x86-cpus}
The default `lancedb` wheel targets `x86-64-haswell` (AVX2 + FMA + F16C). On older x86_64 CPUs without AVX2
(Intel Sandy Bridge, Ivy Bridge, Westmere; AMD Bulldozer, Piledriver, Steamroller), `import lancedb` crashes
with `Illegal instruction`.
Install `lancedb-compat` instead. It exposes the same API (`import lancedb` still works), is built at the
`x86-64-v2` baseline, and uses runtime SIMD dispatch to still use AVX2, FMA, or AVX-512 when available:
<CodeGroup>
```bash Python (pip) icon="terminal"
pip install lancedb-compat
```
</CodeGroup>
The two packages share the same `lancedb/` namespace and conflict at install time, so pick one. To switch,
uninstall the other first (`pip uninstall lancedb && pip install lancedb-compat`).
</Accordion>
## 2\. Connect to a database {#2-connect-to-a-lancedb-database}
### Local directory {#connect-via-local-directory-path}
LanceDB creates an `ex_lancedb` directory to store your tables. No server is needed.
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyConnect}
</CodeBlock>
<CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
{"import * as lancedb from \"@lancedb/lancedb\";\n\n"}
{TsConnect}
</CodeBlock>
<CodeBlock filename="Rust" language="Rust" icon="rust">
{"use lancedb::connect;\n\n"}
{RsConnect}
</CodeBlock>
</CodeGroup>
For Python's async API, see [Connecting to a database](/basics/catalog).
### Object storage {#connect-via-object-storage-uris}
Use an `s3://`, `gs://`, or `az://` URI in place of the local path. See [Object storage](/basics/catalog#object-storage) for credentials and provider-specific options.
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyConnectObjectStorage}
</CodeBlock>
<CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
{"import * as lancedb from \"@lancedb/lancedb\";\n\n"}
{TsConnectObjectStorage}
</CodeBlock>
<CodeBlock filename="Rust" language="Rust" icon="rust">
{"use lancedb::connect;\n\n"}
{RsConnectObjectStorage}
</CodeBlock>
</CodeGroup>
### Enterprise {#connect-to-lancedb-enterprise}
Use the database URI, API key, and endpoint provided by your administrator or the LanceDB team. Replace the placeholders below with those details. Use the deployment's region if provided; otherwise keep `us-east-1`.
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyConnectEnterprisePlaceholders}
</CodeBlock>
<CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
{"import * as lancedb from \"@lancedb/lancedb\";\n\n"}
{TsConnectEnterprisePlaceholders}
</CodeBlock>
<CodeBlock filename="Rust" language="Rust" icon="rust">
{"use lancedb::connect;\n\n"}
{RsConnectEnterprisePlaceholders}
</CodeBlock>
</CodeGroup>
<Note>
In application code, load credentials from environment variables or a secrets manager. See [connection settings](/basics/catalog#enterprise) for an example.
</Note>
Need a deployment? [Contact the LanceDB team](https://www.lancedb.com/contact). For differences between local and server execution, see [LanceDB Enterprise](/index#architecture).
## 3\. Create a table and add data {#3-create-a-new-table}
Each row describes a frame from a robot video clip and stores an embedding alongside its video, caption, and quality stats.
<Info>
These embeddings are made up for this example. In your application, use an embedding model to generate them from your data.
</Info>
<Accordion title="Frame records">
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyQuickstartData}
</CodeBlock>
<CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
{TsQuickstartData}
</CodeBlock>
<CodeBlock filename="Rust" language="Rust" icon="rust">
{RsQuickstartDefineStruct}
{RsQuickstartData}
</CodeBlock>
</CodeGroup>
</Accordion>
Create a `frames` table from those records:
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyQuickstartCreateTable}
</CodeBlock>
<CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
{TsQuickstartCreateTable}
</CodeBlock>
<CodeBlock filename="Rust" language="Rust" icon="rust">
{RsQuickstartCreateTable}
</CodeBlock>
</CodeGroup>
This example uses overwrite mode so you can run it again. It replaces any existing `frames` table in the database you connect to.
Add one more frame:
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyQuickstartAddData}
</CodeBlock>
<CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
{TsQuickstartAddData}
</CodeBlock>
<CodeBlock filename="Rust" language="Rust" icon="rust">
{RsQuickstartAddData}
</CodeBlock>
</CodeGroup>
## 4\. Search the table {#4-semantic-search}
Find the two embeddings closest to the query embedding. This example uses a fixed embedding; it does not call an embedding model.
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{"# Search for frames similar to \"a gripper closing on an object\"\nquery_vector = [0.2, 0.8, 0.4, 0.9]\n\n# Ensure you run `pip install pandas` beforehand\nresult = (\n table.search(query_vector)\n .select([\"frame_id\", \"video_id\", \"caption\", \"_distance\"])\n .limit(2)\n .to_pandas()\n)\nprint(result)\n"}
</CodeBlock>
<CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
{TsQuickstartVectorSearch1}
</CodeBlock>
<CodeBlock filename="Rust" language="Rust" icon="rust">
{RsQuickstartVectorSearch1}
</CodeBlock>
</CodeGroup>
Frames 2 and 4 come back first -- the gripper closing on the cup, then lowering it. Python displays a Pandas DataFrame, Rust displays a Polars DataFrame, and TypeScript displays an array of results. The `_distance` column measures how far each result is from your query embedding, with smaller values indicating a closer match.
## 5\. Curate data with SQL {#5-curate-with-sql}
<Info>
Step 5 needs LanceDB Enterprise: SQL is an Enterprise feature. If you're
using LanceDB Embedded, skip ahead to
[Flatten nested fields](#flatten-nested-fields) below.
</Info>
LanceDB Enterprise accepts SQL over the same connection, for sampling, joins, and
curation tasks that go beyond a single table scan. Draw a quick sample to look
at the data:
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyQuickstartCurateSample}
</CodeBlock>
</CodeGroup>
See [SQL](/basics/sql) for the Flight SQL client and CLI alternatives to `execute_query()`.
Now add a near-duplicate frame -- frame 5 is one video frame after frame 2, with
an almost identical embedding -- and build the vector index that `dedupe` reads:
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyQuickstartCurateDedupeSetup}
</CodeBlock>
</CodeGroup>
Collapse near-duplicates into a materialized view that stays current as new frames arrive, then read it back:
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyQuickstartCurateDedupe}
</CodeBlock>
</CodeGroup>
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyQuickstartCurateDedupeQuery}
</CodeBlock>
</CodeGroup>
Frames 2 and 5 collapse into one representative -- five rows become four.
Which of the two ids survives is not guaranteed to stay the same across
appends, so don't treat it as a stable identifier for the cluster. See
[Deduplicate near-duplicate records](/curation/dedupe) for `duplicate_pairs`,
resolution strategies, and tuning `distance_threshold`, and
[Statistical Sampling](/curation/statistical-sampling) for percentage samples,
repeatable draws, and sampling across a join.
## 6\. Add a derived feature {#6-add-a-derived-feature}
### Flatten nested fields {#flatten-nested-fields}
A UDF binds to top-level columns, so flatten the fields inside `stats` first.
This is a plain eager `add_columns` call, so it works the same on LanceDB
Embedded and LanceDB Enterprise -- [step 8](#8-train) needs these columns
either way:
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyQuickstartFlattenStats}
</CodeBlock>
</CodeGroup>
<Info>
The rest of this step needs LanceDB Enterprise -- Functions are an
Enterprise feature. If you're using LanceDB Embedded, skip ahead to
[step 7](#7-store-multimodal-data).
</Info>
Register a UDF as a Function, then call it to fill a column computed from
those flattened fields. This fills every existing row once, immediately:
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyQuickstartAddFeature}
</CodeBlock>
</CodeGroup>
Read it back like any other column:
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{"features = table.search().select([\"frame_id\", \"video_id\", \"quality_score\"]).limit(10).to_pandas()\nprint(features)\n"}
</CodeBlock>
</CodeGroup>
`refresh_column` fills only rows added since the last refresh and recomputes rows whose inputs changed, leaving unchanged rows alone. Run the same refresh as a background job instead, so it doesn't block:
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyQuickstartAddFeatureEnterprise}
</CodeBlock>
</CodeGroup>
See [Create a Function](/curation/create-function) for UDFs that call external
models or services, and [Computed columns](/feature-engineering/add-computed-column)
for the SQL-expression form that doesn't need a registered Function.
## 7\. Store multimodal data {#7-store-multimodal-data}
Store images, audio, or other binary data alongside vectors and metadata, in a column of raw bytes. This creates a new table from one image file -- replace the path with one of your own:
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyQuickstartMultimodalBytes}
</CodeBlock>
<CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
{TsQuickstartMultimodalBytes}
</CodeBlock>
<CodeBlock filename="Rust" language="Rust" icon="rust">
{RsQuickstartMultimodalBytes}
</CodeBlock>
</CodeGroup>
See [Multimodal data types](/management/table#multimodal) for larger payloads and the Blob v2 column type, which avoids loading binary data on every scan.
## 8\. Train on your data {#8-train}
Read table data into PyTorch, projecting and shuffling only the columns a training step needs:
<CodeGroup>
<CodeBlock filename="Python" language="Python" icon="python">
{PyQuickstartTraining}
</CodeBlock>
</CodeGroup>
`StreamingDataset` wraps a table for PyTorch training reads; `columns` projects before reading, so a training step touches only the columns it selects, not unused ones such as `caption` or `embedding`. It works the same way against LanceDB Embedded and LanceDB Enterprise. See [PyTorch Data Loader](/training/data-loading) for shuffling, transforms, resuming, and multi-worker loading, and [Permutation](/training/permutation) for the lower-level row-ordering primitive it's built on.
## Where to go next {#next-steps}
<Columns cols={2}>
<Card title="Basic table operations" icon="table" href="/management/table">
Create, update, and manage your tables.
</Card>
<Card title="Build a RAG app" icon="search" href="/tutorials/agents/contextual-rag">
Use retrieved context in a language model application.
</Card>
<Card title="Indexing" icon="layer-group" href="/indexing/">
Speed up queries on larger datasets.
</Card>
<Card title="Embedding models" icon="vector-square" href="/embedding/">
Generate vectors from your own data.
</Card>
</Columns>