Struct SourceSchema 

pub struct SourceSchema {
    pub name: String,
    pub projections: Vec<(String, PortType)>,
    pub extent: Option<u64>,
    pub extent_outputs: Option<(String, String)>,
    pub extent_limit: Option<u64>,
    pub cursor_kind: CursorKind,
    pub partition_output: Option<String>,
}

Schema describing what a source yields.

Fields

name: String

Source name as declared in the Polydat graph.

projections: Vec<(String, PortType)>

Field names and types available for projection (e.g., ordinal: U64, vector: Json).

extent: Option<u64>

Known extent, if finite. None for infinite sources.

None may also mean the extent is computable but only at runtime (e.g., the cursor’s range(...) bounds depend on iteration-variable externs). In that case extent_outputs carries the kernel output names whose values yield [start, end) once externs are bound.

extent_outputs: Option<(String, String)>

Optional aux output names (start, end) that the runtime can pull from the kernel after externs are populated to compute extent. Set when range(...) bounds are non-literal (e.g., wire-bound dataset function calls). The compiler also writes back to extent if both values fold to constants at compile time.

extent_limit: Option<u64>

Optional cursor limit clamp (from --limit / limit= param). Applied after runtime extent evaluation.

cursor_kind: CursorKind

What kind of cursor this is. Default Range (the legacy bounded-finite cursor); ExtendingTimed { ... } declares the cursor as runtime-extending under a wall-clock minimum-duration policy. The executor branches on this to pick between RangeSourceFactory and ExtendingRangeSourceFactory at phase setup.

partition_output: Option<String>

SRD 71: name of the kernel output that carries the partition-narrowing source (the over <expr> clause on the cursor declaration). The executor pulls this output at phase setup and applies it to the source factory’s [start, end) range. The output value’s type drives the resolution:

• Value::Str(s) — parse s as a partition spec, resolve, use partition 0.
• Value::Ext(Partition) — use the resolved partition’s start_ord / end_ord.
• Value::Ext(PartitionSpec) — resolve against the cursor’s extent, use partition 0.
• Value::Ext(PartitionList) — use partition 0.
• Value::None — no narrowing (cursor uses its full extent).

None means the cursor was declared without an over clause; the cursor uses its full declared extent.

Trait Implementations

impl Clone for SourceSchema

fn clone(&self) -> SourceSchema

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SourceSchema

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.