Struct PhysicalOptionalExtend 

pub struct PhysicalOptionalExtend {
    pub rel_table_name: String,
    pub rel_table_id: u64,
    pub rel_var: String,
    pub src_node_var: String,
    pub dst_node_var: String,
    pub direction: EdgeDirection,
    pub table_catalog: Arc<TableCatalog>,
}

Physical operator for OPTIONAL MATCH over an already-bound pair of node variables, e.g. OPTIONAL MATCH (a)-[existing:Connected]-(b) where both a and b come from the mandatory side (P53.25).

For each input row the relationship-table adjacency is probed for an edge between the source and destination node ids. When an edge exists, its property columns (plus an internal {rel_var}._id holding the edge index) are emitted; when no edge exists, those columns are NULL-padded and exactly one row is still produced (outer-join semantics).

Fan-out mode (P53.40): when dst_node_var is empty the destination is anonymous — OPTIONAL MATCH (m)-[r:R]-(:T) — so EVERY edge incident on the source becomes one output row (zero edges still yield one NULL-padded row). This preserves multi-edge cardinality for downstream aggregates such as WITH m, COUNT(r) AS cnt; the previous fallback routed such patterns through a cross-product merge that duplicated every left row.

Output layout: [input_fields | rel_properties | {rel_var}._id].

Fields

rel_table_name: String

Name of the relationship table to probe.

rel_table_id: u64

ID of the relationship table.

rel_var: String

Variable name of the relationship (e.g., “existing”); prefix for the emitted edge property columns.

src_node_var: String

Variable name of the bound source node (e.g., “a”).

dst_node_var: String

Variable name of the bound destination node (e.g., “b”). Empty string selects fan-out mode: all edges incident on the source are emitted.

direction: EdgeDirection

Direction of the probe (forward, backward, or both).

table_catalog: Arc<TableCatalog>

Table catalog for data access.

Implementations

impl PhysicalOptionalExtend

pub fn execute( &self, input: Vec<DataChunk>, ) -> Result<Vec<DataChunk>, ProcessorError>