[**@lancedb/lancedb**](../README.md) • **Docs**

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[@lancedb/lancedb](../globals.md) / Session

# Class: Session

A session for managing caches and object stores across LanceDB operations.

Sessions allow you to configure cache sizes for index and metadata caches,
which can significantly impact performance for large datasets.

## Constructors

### new Session()

```ts
new Session(indexCacheSizeBytes?, metadataCacheSizeBytes?): Session
```

Create a new session with custom cache sizes.

# Parameters

- `index_cache_size_bytes`: The size of the index cache in bytes.
  Defaults to 6GB if not specified.
- `metadata_cache_size_bytes`: The size of the metadata cache in bytes.
  Defaults to 1GB if not specified.

#### Parameters

* **indexCacheSizeBytes?**: `null` \| `bigint`

* **metadataCacheSizeBytes?**: `null` \| `bigint`

#### Returns

[`Session`](Session.md)

## Methods

### approxNumItems()

```ts
approxNumItems(): number
```

Get the approximate number of items cached in the session.

#### Returns

`number`

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### sizeBytes()

```ts
sizeBytes(): bigint
```

Get the current size of the session caches in bytes.

#### Returns

`bigint`

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### default()

```ts
static default(): Session
```

Create a session with default cache sizes.

This is equivalent to creating a session with 6GB index cache
and 1GB metadata cache.

#### Returns

[`Session`](Session.md)