Struct Coordinator 

pub struct Coordinator { /* private fields */ }

The query coordinator (spec section 12.10): registers the query with the existing SqlQueryRegistry (so registry.cancel(...) reaches every fragment through the ExecutionControl hierarchy), reserves resources per fragment, fans out cancellation to every fragment, sweeps expired worker leases to clean abandoned fragments, and merges producer streams per the exchange descriptors with the real in-memory operators.

Implementations

impl Coordinator

pub fn new( transport: Arc<dyn FragmentTransport>, registry: Arc<SqlQueryRegistry>, ) -> Self

A coordinator with default limits (1024 concurrent fragments, 16 GiB of estimated bytes, 30 second worker leases).

pub fn with_limits( transport: Arc<dyn FragmentTransport>, registry: Arc<SqlQueryRegistry>, max_fragments: usize, max_bytes: u64, lease_ttl: Duration, ) -> Self

A coordinator with explicit resource limits and lease TTL.

pub fn resources(&self) -> &Arc<ResourceLedger>

The fragment resource ledger (test introspection).

pub async fn execute( &self, plan: &DistributedPlan, ) -> DistributedResult<Vec<RecordBatch>>

Executes a distributed plan to completion, returning the root fragment’s output batches.

The plan’s QueryId is registered with the query registry first; every fragment runs under a child ExecutionControl of that registration, so a registry-level cancel fans out to all fragments. Fragments execute layer by layer (producers before consumers), concurrently within a layer. The coordinator-local root fragment’s merge operators (FragmentOperator::MergeSort, FragmentOperator::FinalAggregate, FragmentOperator::DistributedTopK, FragmentOperator::DistributedLimit) run over the producer streams for real.

pub fn cancel_query(&self, query_id: &QueryId) -> DistributedResult<bool>

Cancels a running distributed query: registry cancel (which reaches every fragment control through the parent-child hierarchy) plus an explicit transport cancel per in-flight fragment (spec section 12.10: “cancellation fans out to every fragment”). Returns true when the registry accepted (or already observed) the cancellation.

pub fn sweep_expired_leases(&self, now: Instant) -> usize

Sweeps expired worker leases and cleans their abandoned in-flight fragments: cancels the fragment control (as CancellationReason::ServerShutdown), notifies the transport, and releases the resource reservation (spec section 12.10: “worker lease expiry cleans abandoned fragments”). Returns the number of fragments cleaned.