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>,
    pub partitions: Option<Vec<Partition>>,
}

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, taken from CompileOptions::cursor_limit (a host’s --limit-style option). Applied after runtime extent evaluation.

cursor_kind: CursorKind

What kind of cursor this is. Default Range, the bounded range(start, end) cursor; the Extending* variants declare a runtime-extending cursor under a wall-clock, count, or predicate policy. A host picks ExtendingRangeSourceFactory for those, and cursor_over_partitions treats them as open-extent when it resolves an over clause.

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). cursor_over_partitions pulls it and resolves it through cursor_partition::resolve_over into the full partition list: a spec string or a PartitionSpec resolves against the cursor’s extent, a Partition or a PartitionList is re-projected onto it, and Value::None yields no partitions. A host, such as activation setup, selects one partition and writes it with set_cursor.

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

partitions: Option<Vec<Partition>>

The partitions the over clause denotes, resolved by the compiler when the clause is a literal spec and the extent is known at build (engine_parity.md, step 3). A host reads them without evaluating anything; cursor_over_partitions returns them without a pull. None when the clause or the extent is only known at run time, or the cursor has no over clause.

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.