Trait WorkerSessionBuilder 

pub trait WorkerSessionBuilder {
    // Required method
    fn build_session_state<'life0, 'async_trait>(
        &'life0 self,
        ctx: WorkerQueryContext,
    ) -> Pin<Box<dyn Future<Output = Result<SessionState, DataFusionError>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait;
}

builds a DataFusion’s SessionState in each query issued to a worker.

Required Methods

fn build_session_state<'life0, 'async_trait>( &'life0 self, ctx: WorkerQueryContext, ) -> Pin<Box<dyn Future<Output = Result<SessionState, DataFusionError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Builds a custom SessionState scoped to a single ArrowFlight gRPC call, allowing the users to provide a customized DataFusion session with things like custom extension codecs, custom physical optimization rules, UDFs, UDAFs, config extensions, etc…

Example:

#[derive(Debug)]
struct CustomExecCodec;

impl PhysicalExtensionCodec for CustomExecCodec {
    fn try_decode(&self, buf: &[u8], inputs: &[Arc<dyn ExecutionPlan>], ctx: &TaskContext) -> datafusion::common::Result<Arc<dyn ExecutionPlan>> {
        todo!()
    }

    fn try_encode(&self, node: Arc<dyn ExecutionPlan>, buf: &mut Vec<u8>) -> datafusion::common::Result<()> {
        todo!()
    }
}

#[derive(Clone)]
struct CustomSessionBuilder;

#[async_trait]
impl WorkerSessionBuilder for CustomSessionBuilder {
    async fn build_session_state(&self, ctx: WorkerQueryContext) -> Result<SessionState, DataFusionError> {
        Ok(ctx
            .builder
            .with_distributed_user_codec(CustomExecCodec)
            // Add your UDFs, optimization rules, etc...
            .build())
    }
}

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl WorkerSessionBuilder for DefaultSessionBuilder

impl<F, Fut> WorkerSessionBuilder for F

where F: Fn(WorkerQueryContext) -> Fut + Send + Sync + 'static, Fut: Future<Output = Result<SessionState, DataFusionError>> + Send + 'static,

Implementation of WorkerSessionBuilder for any async function that returns a Result

impl<T, F> WorkerSessionBuilder for MappedWorkerSessionBuilder<T, F>

where T: WorkerSessionBuilder + Send + Sync + 'static, F: Fn(SessionStateBuilder) -> Result<SessionState, DataFusionError> + Send + Sync,