Implementation:Lance format Lance LanceNamespaceTrait

Knowledge Sources	Lance
Domains	Namespace, Infrastructure
Last Updated	2026-02-08 19:33 GMT

Overview

Description

The LanceNamespace trait defines the base interface that all Lance namespace implementations must provide. It is an async_trait requiring Send + Sync + Debug, and it declares a comprehensive set of async methods covering namespace management, table lifecycle, data manipulation, indexing, tagging, transactions, and query planning.

Each method has a default implementation that returns Error::NotSupported, allowing backends to incrementally implement only the operations they support. The trait relies on request/response types from the lance_namespace_reqwest_client::models module, which are generated from the Lance Namespace REST specification.

Key method categories:

Namespace operations -- list_namespaces, describe_namespace, create_namespace, drop_namespace, namespace_exists
Table operations -- list_tables, describe_table, register_table, create_table, drop_table, rename_table, restore_table
Data operations -- insert_into_table, delete_from_table, update_table, merge_insert_into_table, query_table
Index operations -- create_table_index, drop_table_index, list_table_indices
Tag operations -- create_table_tag, update_table_tag, delete_table_tag, list_table_tags
Transaction operations -- alter_transaction, describe_transaction

Usage

Concrete implementations of this trait are provided in the lance-namespace-impls crate (e.g., REST client, local filesystem). The trait is used by higher-level catalog abstractions to manage Lance datasets across various storage backends.

Code Reference

Source Location

rust/lance-namespace/src/namespace.rs

Signature

#[async_trait]
pub trait LanceNamespace: Send + Sync + std::fmt::Debug {
    async fn list_namespaces(
        &self,
        _request: ListNamespacesRequest,
    ) -> Result<ListNamespacesResponse>;

    async fn create_namespace(
        &self,
        _request: CreateNamespaceRequest,
    ) -> Result<CreateNamespaceResponse>;

    async fn drop_namespace(
        &self,
        _request: DropNamespaceRequest,
    ) -> Result<DropNamespaceResponse>;

    async fn list_tables(
        &self,
        _request: ListTablesRequest,
    ) -> Result<ListTablesResponse>;

    async fn create_table(
        &self,
        _request: CreateTableRequest,
    ) -> Result<CreateTableResponse>;

    async fn query_table(
        &self,
        _request: QueryTableRequest,
    ) -> Result<Bytes>;

    // ... 30+ additional methods with default NotSupported implementations
}

Import

use lance_namespace::namespace::LanceNamespace;

I/O Contract

Inputs

Parameter	Type	Description
request	Various `*Request` structs	Operation-specific request objects from `lance_namespace_reqwest_client::models`

Outputs

Type	Description
`Result<*Response>`	Operation-specific response wrapped in `lance_core::Result`
`Result<Bytes>`	Raw byte response for query operations (e.g., Arrow IPC)
`Result<()>`	Success/failure indicator for existence checks

Usage Examples

use lance_namespace::namespace::LanceNamespace;
use lance_namespace_reqwest_client::models::{
    ListNamespacesRequest, CreateNamespaceRequest,
};

async fn example(ns: &dyn LanceNamespace) -> lance_core::Result<()> {
    // List child namespaces
    let response = ns.list_namespaces(ListNamespacesRequest::default()).await?;
    println!("Namespaces: {:?}", response);

    // Create a new namespace
    let create_req = CreateNamespaceRequest { /* ... */ };
    let created = ns.create_namespace(create_req).await?;
    Ok(())
}

Related Pages

Lance_format_Lance_NamespaceError -- Error types returned by namespace operations
Lance_format_Lance_NamespaceSchema -- Schema conversion used by table operations
Lance_format_Lance_RestApi -- REST specification that mirrors this trait's operations

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