Module context 

Query context and session abstractions for DataFusion integration.

This module provides the core abstractions for executing queries against registered connectors:

• QuerySession: An abstraction over DataFusion’s SessionContext that allows custom implementations to control session behavior, capabilities, and SQL execution. The default implementation wraps SessionContext directly.

• QueryContext: The high-level interface combining a session and a ConnectorRegistry. It handles connector registration, catalog discovery, and query execution.

• SessionCapability: Describes what actions a session supports (e.g., executing queries without specifying a connector).

Custom Sessions

Implement QuerySession to customize DataFusion behavior:

use async_trait::async_trait;
use datafusion::execution::context::SessionContext;
use stately_arrow::{QuerySession, SessionCapability, Result};

#[derive(Clone)]
pub struct MySession {
    inner: SessionContext,
}

#[async_trait]
impl QuerySession for MySession {
    fn as_session(&self) -> &SessionContext { &self.inner }
    fn capabilities(&self) -> &[SessionCapability] { &[] }
    async fn sql(&self, sql: &str) -> Result<DataFrame> {
        // Custom SQL handling
    }
}

Structs

QueryContext

Query context for interactive data exploration.

Enums

SessionCapability

Session capabilities a QuerySession can expose to the QueryContext.

Constants

DEFAULT_SESSION_CAPABILITIES

Traits

QuerySession

Abstraction over a query-capable DataFusion session.