Struct dataflow::server::PendingPeek

struct PendingPeek {
    id: GlobalId,
    key: Option<Row>,
    conn_id: u32,
    timestamp: Timestamp,
    finishing: RowSetFinishing,
    map_filter_project: SafeMfpPlan,
    trace_bundle: TraceBundle,
}

An in-progress peek, and data to eventually fulfill it.

Note that PendingPeek intentionally does not implement or derive Clone, as each PendingPeek is meant to be dropped after it’s responded to.

Fields

id: GlobalId

The identifier of the dataflow to peek.

key: Option<Row>

An optional key to use for the arrangement.

conn_id: u32

The ID of the connection that submitted the peek. For logging only.

timestamp: Timestamp

Time at which the collection should be materialized.

finishing: RowSetFinishing

Finishing operations to perform on the peek, like an ordering and a limit.

map_filter_project: SafeMfpPlan

Linear operators to apply in-line to all results.

trace_bundle: TraceBundle

The data from which the trace derives.

Implementations

impl PendingPeek

pub fn as_log_event(&self) -> Peek

Produces a corresponding log event.

fn seek_fulfillment(
    &mut self,
    upper: &mut Antichain<Timestamp>
) -> Option<PeekResponse>

Attempts to fulfill the peek and reports success.

To produce output at peek.timestamp, we must be certain that it is no longer changing. A trace guarantees that all future changes will be greater than or equal to an element of upper.

If an element of upper is less or equal to peek.timestamp, then there can be further updates that would change the output. If no element of upper is less or equal to peek.timestamp, then for any time t less or equal to peek.timestamp it is not the case that upper is less or equal to that timestamp, and so the result cannot further evolve.

fn collect_finished_data(&mut self) -> Result<Vec<Row>, String>

Collects data for a known-complete peek.