lancedb/docs/src/guides/sql_querying.md

SQL Querying

You can use DuckDB and Apache Datafusion to query your LanceDB tables using SQL. This guide will show how to query Lance tables them using both.

We will re-use the dataset created previously:

import lancedb

db = lancedb.connect("data/sample-lancedb")
data = [
    {"vector": [3.1, 4.1], "item": "foo", "price": 10.0},
    {"vector": [5.9, 26.5], "item": "bar", "price": 20.0}
]
table = db.create_table("pd_table", data=data)

Querying a LanceDB Table with DuckDb

The to_lance method converts the LanceDB table to a LanceDataset, which is accessible to DuckDB through the Arrow compatibility layer. To query the resulting Lance dataset in DuckDB, all you need to do is reference the dataset by the same name in your SQL query.

import duckdb

arrow_table = table.to_lance()

duckdb.query("SELECT * FROM arrow_table")

vector	item	price
[3.1, 4.1]	foo	10.0
[5.9, 26.5]	bar	20.0

Querying a LanceDB Table with Apache Datafusion

Have the required imports before doing any querying.

=== "Python"

```python
--8<-- "python/python/tests/docs/test_guide_tables.py:import-lancedb"
--8<-- "python/python/tests/docs/test_guide_tables.py:import-session-context"
--8<-- "python/python/tests/docs/test_guide_tables.py:import-ffi-dataset"
```

Register the table created with the Datafusion session context.

=== "Python"

```python
--8<-- "python/python/tests/docs/test_guide_tables.py:lance_sql_basic"
```

vector	item	price
[3.1, 4.1]	foo	10.0
[5.9, 26.5]	bar	20.0