lancedb/docs/src/guides/tables.md

A Table is a collection of Records in a LanceDB Database. Tables in Lance have a schema that defines the columns and their types. These schemas can include nested columns and can evolve over time.

This guide will show how to create tables, insert data into them, and update the data. You can follow along on colab!

Creating a LanceDB Table

=== "Python" ### LanceDB Connection

```python
import lancedb
db = lancedb.connect("./.lancedb")
```

LanceDB allows ingesting data from various sources - `dict`, `list[dict]`, `pd.DataFrame`, `pa.Table` or a `Iterator[pa.RecordBatch]`. Let's take a look at some of the these.

### From list of tuples or dictionaries

```python
import lancedb

db = lancedb.connect("./.lancedb")

data = [{"vector": [1.1, 1.2], "lat": 45.5, "long": -122.7},
        {"vector": [0.2, 1.8], "lat": 40.1, "long": -74.1}]

db.create_table("my_table", data)

db["my_table"].head()
```

!!! info "Note"
    If the table already exists, LanceDB will raise an error by default. If you want to overwrite the table, you can pass in mode="overwrite" to the createTable function.

    ```python
    db.create_table("name", data, mode="overwrite")
    ```


### From pandas DataFrame

```python
import pandas as pd

data = pd.DataFrame({
    "vector": [[1.1, 1.2, 1.3, 1.4], [0.2, 1.8, 0.4, 3.6]],
    "lat": [45.5, 40.1],
    "long": [-122.7, -74.1]
})

db.create_table("table2", data)

db["table2"].head()
```
!!! info "Note"
    Data is converted to Arrow before being written to disk. For maximum control over how data is saved, either provide the PyArrow schema to convert to or else provide a PyArrow Table directly.

```python
custom_schema = pa.schema([
pa.field("vector", pa.list_(pa.float32(), 4)),
pa.field("lat", pa.float32()),
pa.field("long", pa.float32())
])

table = db.create_table("table3", data, schema=custom_schema)
```

### From PyArrow Tables
You can also create LanceDB tables directly from pyarrow tables

```python
table = pa.Table.from_arrays(
        [
            pa.array([[3.1, 4.1, 5.1, 6.1], [5.9, 26.5, 4.7, 32.8]],
                    pa.list_(pa.float32(), 4)),
            pa.array(["foo", "bar"]),
            pa.array([10.0, 20.0]),
        ],
        ["vector", "item", "price"],
    )

db = lancedb.connect("db")

tbl = db.create_table("test1", table)
```

### From Pydantic Models
When you create an empty table without data, you must specify the table schema.
LanceDB supports creating tables by specifying a pyarrow schema or a specialized
pydantic model called `LanceModel`.

For example, the following Content model specifies a table with 5 columns:
movie_id, vector, genres, title, and imdb_id. When you create a table, you can
pass the class as the value of the `schema` parameter to `create_table`.
The `vector` column is a `Vector` type, which is a specialized pydantic type that
can be configured with the vector dimensions. It is also important to note that
LanceDB only understands subclasses of `lancedb.pydantic.LanceModel`
(which itself derives from `pydantic.BaseModel`).

```python
from lancedb.pydantic import Vector, LanceModel

class Content(LanceModel):
    movie_id: int
    vector: Vector(128)
    genres: str
    title: str
    imdb_id: int

    @property
    def imdb_url(self) -> str:
        return f"https://www.imdb.com/title/tt{self.imdb_id}"

import pyarrow as pa
db = lancedb.connect("~/.lancedb")
table_name = "movielens_small"
table = db.create_table(table_name, schema=Content)
```

#### Nested schemas

Sometimes your data model may contain nested objects.
For example, you may want to store the document string
and the document soure name as a nested Document object:

```python
class Document(BaseModel):
    content: str
    source: str
```

This can be used as the type of a LanceDB table column:

```python
class NestedSchema(LanceModel):
    id: str
    vector: Vector(1536)
    document: Document

tbl = db.create_table("nested_table", schema=NestedSchema, mode="overwrite")
```

This creates a struct column called "document" that has two subfields 
called "content" and "source":

```
In [28]: tbl.schema
Out[28]:
id: string not null
vector: fixed_size_list<item: float>[1536] not null
    child 0, item: float
document: struct<content: string not null, source: string not null> not null
    child 0, content: string not null
    child 1, source: string not null    
```

#### Validators

Note that neither pydantic nor pyarrow automatically validates that input data
is of the *correct* timezone, but this is easy to add as a custom field validator:

```python
from datetime import datetime
from zoneinfo import ZoneInfo

from lancedb.pydantic import LanceModel
from pydantic import Field, field_validator, ValidationError, ValidationInfo

tzname = "America/New_York"
tz = ZoneInfo(tzname)

class TestModel(LanceModel):
    dt_with_tz: datetime = Field(json_schema_extra={"tz": tzname})

    @field_validator('dt_with_tz')
    @classmethod
    def tz_must_match(cls, dt: datetime) -> datetime:
        assert dt.tzinfo == tz
        return dt        

ok = TestModel(dt_with_tz=datetime.now(tz))

try:
    TestModel(dt_with_tz=datetime.now(ZoneInfo("Asia/Shanghai")))
    assert 0 == 1, "this should raise ValidationError"
except ValidationError:
    print("A ValidationError was raised.")
    pass
```

When you run this code it should print "A ValidationError was raised."

#### Pydantic custom types

LanceDB does NOT yet support converting pydantic custom types. If this is something you need,
please file a feature request on the [LanceDB Github repo](https://github.com/lancedb/lancedb/issues/new).

### Using Iterators / Writing Large Datasets

It is recommended to use itertators to add large datasets in batches when creating your table in one go. This does not create multiple versions of your dataset unlike manually adding batches using `table.add()`

LanceDB additionally supports pyarrow's `RecordBatch` Iterators or other generators producing supported data types.

Here's an example using using `RecordBatch` iterator for creating tables.

```python
import pyarrow as pa

def make_batches():
    for i in range(5):
        yield pa.RecordBatch.from_arrays(
            [
                pa.array([[3.1, 4.1, 5.1, 6.1], [5.9, 26.5, 4.7, 32.8]],
                        pa.list_(pa.float32(), 4)),
                pa.array(["foo", "bar"]),
                pa.array([10.0, 20.0]),
            ],
            ["vector", "item", "price"],
        )

schema = pa.schema([
    pa.field("vector", pa.list_(pa.float32(), 4)),
    pa.field("item", pa.utf8()),
    pa.field("price", pa.float32()),
])

db.create_table("table4", make_batches(), schema=schema)
```

You can also use iterators of other types like Pandas dataframe or Pylists directly in the above example.

## Creating Empty Table
You can create empty tables in python. Initialize it with schema and later ingest data into it.

```python
import lancedb
import pyarrow as pa

schema = pa.schema(
  [
      pa.field("vector", pa.list_(pa.float32(), 2)),
      pa.field("item", pa.string()),
      pa.field("price", pa.float32()),
  ])
tbl = db.create_table("table5", schema=schema)
data = [
    {"vector": [3.1, 4.1], "item": "foo", "price": 10.0},
    {"vector": [5.9, 26.5], "item": "bar", "price": 20.0},
]
tbl.add(data=data)
```

You can also use Pydantic to specify the schema

```python
import lancedb
from lancedb.pydantic import LanceModel, vector

class Model(LanceModel):
      vector: Vector(2)

tbl = db.create_table("table5", schema=Model.to_arrow_schema())
```

=== "Javascript/Typescript"

### VectorDB Connection

```javascript
const lancedb = require("vectordb");

const uri = "data/sample-lancedb";
const db = await lancedb.connect(uri);
```

### Creating a Table

You can create a LanceDB table in javascript using an array of records.

```javascript
data
const tb = await db.createTable("my_table",
  [{"vector": [3.1, 4.1], "item": "foo", "price": 10.0},
   {"vector": [5.9, 26.5], "item": "bar", "price": 20.0}])
```

!!! info "Note"
If the table already exists, LanceDB will raise an error by default. If you want to overwrite the table, you need to specify the `WriteMode` in the createTable function.

```javascript
const table = await con.createTable(tableName, data, { writeMode: WriteMode.Overwrite })
```

Open existing tables

If you forget the name of your table, you can always get a listing of all table names:

=== "Python" ### Get a list of existing Tables

```python
print(db.table_names())
```

=== "Javascript/Typescript"

```javascript
console.log(await db.tableNames());
```

Then, you can open any existing tables

=== "Python"

```python
tbl = db.open_table("my_table")
```

=== "Javascript/Typescript"

```javascript
const tbl = await db.openTable("my_table");
```

Adding to a Table

After a table has been created, you can always add more data to it using

=== "Python" You can add any of the valid data structures accepted by LanceDB table, i.e, dict, list[dict], pd.DataFrame, or a Iterator[pa.RecordBatch]. Here are some examples.

### Adding Pandas DataFrame

```python
df = pd.DataFrame({
    "vector": [[1.3, 1.4], [9.5, 56.2]], "item": ["fizz", "buzz"], "price": [100.0, 200.0]
})
tbl.add(df)
```

You can also add a large dataset batch in one go using Iterator of any supported data types.

### Adding to table using Iterator

```python
def make_batches():
    for i in range(5):
        yield [
                {"vector": [3.1, 4.1], "item": "foo", "price": 10.0},
                {"vector": [5.9, 26.5], "item": "bar", "price": 20.0}
            ]
tbl.add(make_batches())
```

The other arguments accepted:

| Name | Type | Description | Default |
|---|---|---|---|
| data | DATA | The data to insert into the table. | required |
| mode | str | The mode to use when writing the data. Valid values are "append" and "overwrite". | append |
| on_bad_vectors | str | What to do if any of the vectors are not the same size or contains NaNs. One of "error", "drop", "fill". | drop |
| fill value | float | The value to use when filling vectors: Only used if on_bad_vectors="fill". | 0.0 |

=== "Javascript/Typescript"

```javascript
await tbl.add([{vector: [1.3, 1.4], item: "fizz", price: 100.0},
    {vector: [9.5, 56.2], item: "buzz", price: 200.0}])
```

Deleting from a Table

Use the delete() method on tables to delete rows from a table. To choose which rows to delete, provide a filter that matches on the metadata columns. This can delete any number of rows that match the filter.

=== "Python"

```python
tbl.delete('item = "fizz"')
```

### Deleting row with specific column value

```python
import lancedb

data = [{"x": 1, "vector": [1, 2]},
        {"x": 2, "vector": [3, 4]},
        {"x": 3, "vector": [5, 6]}]
db = lancedb.connect("./.lancedb")
table = db.create_table("my_table", data)
table.to_pandas()
#   x      vector
# 0  1  [1.0, 2.0]
# 1  2  [3.0, 4.0]
# 2  3  [5.0, 6.0]

table.delete("x = 2")
table.to_pandas()
#   x      vector
# 0  1  [1.0, 2.0]
# 1  3  [5.0, 6.0]
```

### Delete from a list of values

```python
to_remove = [1, 5]
to_remove = ", ".join(str(v) for v in to_remove)

table.delete(f"x IN ({to_remove})")
table.to_pandas()
#   x      vector
# 0  3  [5.0, 6.0]
```

=== "Javascript/Typescript"

```javascript
await tbl.delete('item = "fizz"')
```

### Deleting row with specific column value

```javascript
const con = await lancedb.connect("./.lancedb")
const data = [
  {id: 1, vector: [1, 2]},
  {id: 2, vector: [3, 4]},
  {id: 3, vector: [5, 6]},
];
const tbl = await con.createTable("my_table", data)
await tbl.delete("id = 2")
await tbl.countRows() // Returns 2
```

### Delete from a list of values

```javascript
const to_remove = [1, 5];
await tbl.delete(`id IN (${to_remove.join(",")})`)
await tbl.countRows() // Returns 1
```

Updating a Table

This can be used to update zero to all rows depending on how many rows match the where clause. The update queries follow the form of a SQL UPDATE statement. The where parameter is a SQL filter that matches on the metadata columns. The values or values_sql parameters are used to provide the new values for the columns.

Parameter	Type	Description
where	str	The SQL where clause to use when updating rows. For example, 'x = 2' or 'x IN (1, 2, 3)'. The filter must not be empty, or it will error.
values	dict	The values to update. The keys are the column names and the values are the values to set.
values_sql	dict	The values to update. The keys are the column names and the values are the SQL expressions to set. For example, {'x': 'x + 1'} will increment the value of the x column by 1.

!!! info "SQL syntax"

See [SQL filters](sql.md) for more information on the supported SQL syntax.

!!! warning "Warning"

Updating nested columns is not yet supported.

=== "Python"

API Reference: [lancedb.table.Table.update][]

```python
import lancedb
import pandas as pd

# Create a lancedb connection
db = lancedb.connect("./.lancedb")

# Create a table from a pandas DataFrame
data = pd.DataFrame({"x": [1, 2, 3], "vector": [[1, 2], [3, 4], [5, 6]]})
table = db.create_table("my_table", data)

# Update the table where x = 2
table.update(where="x = 2", values={"vector": [10, 10]})

# Get the updated table as a pandas DataFrame
df = table.to_pandas()

# Print the DataFrame
print(df)
```

Output
```shell
    x  vector
0  1  [1.0, 2.0]
1  3  [5.0, 6.0]
2  2  [10.0, 10.0]
```

=== "Javascript/Typescript"

API Reference: [vectordb.Table.update](../../javascript/interfaces/Table/#update)

```javascript
const lancedb = require("vectordb");

const db = await lancedb.connect("./.lancedb");

const data = [
  {x: 1, vector: [1, 2]},
  {x: 2, vector: [3, 4]},
  {x: 3, vector: [5, 6]},
];
const tbl = await db.createTable("my_table", data)

await tbl.update({ where: "x = 2", values: {vector: [10, 10]} })
```

The values parameter is used to provide the new values for the columns as literal values. You can also use the values_sql / valuesSql parameter to provide SQL expressions for the new values. For example, you can use values_sql="x + 1" to increment the value of the x column by 1.

=== "Python"

```python
# Update the table where x = 2
table.update(valuesSql={"x": "x + 1"})

print(table.to_pandas())
```

Output
```shell
    x  vector
0  2  [1.0, 2.0]
1  4  [5.0, 6.0]
2  3  [10.0, 10.0]
```

=== "Javascript/Typescript"

```javascript
await tbl.update({ valuesSql: { x: "x + 1" } })
```

!!! info "Note"

When rows are updated, they are moved out of the index. The row will still show up in ANN queries, but the query will not be as fast as it would be if the row was in the index. If you update a large proportion of rows, consider rebuilding the index afterwards.

What's Next?

Learn how to Query your tables and create indices