Struct VarLenExpandNode 

pub struct VarLenExpandNode {
    pub input: Arc<LogicalPlan>,
    pub rel_type_name: String,
    pub min_hops: u16,
    pub max_hops: Option<u16>,
    pub src_var: u32,
    pub dst_var: u32,
    pub edge_var: u32,
    pub direction: Direction,
    pub rel_ty: Option<u32>,
    pub dir: PathBuf,
    pub mode: OntologyMode,
    /* private fields */
}

Physical node for variable-length path expansion.

Triggered when Expand has max_hops != Some(1) — patterns like (a)-[:KNOWS*1..3]->(b). These cannot be expressed as a finite join sequence, so the physical layer (VarLenExpandExec in M13) performs an iterative BFS over the Parquet edge table.

Baked execution context

Like GraphCreateNode, the project dir and ontology mode are baked in at lowering time because the physical-planning ExtensionPlanner only sees the DataFusion session state, not the GraphForge project path. The physical node reads edges directly from dir at execution time.

Output schema

The output extends the input schema with the destination node’s columns (var_<dst>-qualified TOPOLOGY_NODES_SCHEMA), then a trailing edge-list column (var_<edge>-qualified var_len_edge_list_field) binding the edge variable r to the openCypher list of relationships along each path (#709). The edge column is last; the physical node produces columns in this exact order.

Fields

input: Arc<LogicalPlan>

Input plan (the source node scan / prior pipeline).

rel_type_name: String

Name of the relation type to expand along (or "*" for wildcard).

min_hops: u16

Minimum number of hops.

max_hops: Option<u16>

Maximum number of hops (None = unbounded).

src_var: u32

Source node pattern-variable id (the frontier seed in the input).

dst_var: u32

Destination node pattern-variable id (bound to the reached node).

edge_var: u32

Edge pattern-variable id (bound to the per-path relationship list).

direction: Direction

Edge traversal direction.

rel_ty: Option<u32>

Resolved relation type id (TypeId.0), or None for a wildcard.

dir: PathBuf

Project directory the physical node reads edges from.

mode: OntologyMode

Ontology mode (drives typed vs exploratory edge-file routing).

Implementations

impl VarLenExpandNode

pub fn new( input: Arc<LogicalPlan>, rel_type_name: impl Into<String>, min_hops: u16, max_hops: Option<u16>, src_var: u32, dst_var: u32, edge_var: u32, direction: Direction, rel_ty: Option<u32>, dir: PathBuf, mode: OntologyMode, dst_fields: Vec<Arc<Field>>, edge_field: Arc<Field>, ) -> Self

Create a variable-length expand node.

dst_fields is the destination node’s column list (the storage layer’s TOPOLOGY_NODES_SCHEMA fields), passed in by the lowerer so this crate need not depend on graphforge-storage. They are qualified var_<dst_var> and appended to the input schema. edge_field is the trailing edge-list column (var_len_edge_list_field), qualified var_<edge_var>.

Trait Implementations

impl Clone for VarLenExpandNode

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for VarLenExpandNode

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

Formats the value using the given formatter.

impl Eq for VarLenExpandNode

impl Hash for VarLenExpandNode

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for VarLenExpandNode

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialOrd for VarLenExpandNode

fn partial_cmp(&self, _other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for VarLenExpandNode

impl UserDefinedLogicalNodeCore for VarLenExpandNode

fn name(&self) -> &str

Return the plan’s name.

fn inputs(&self) -> Vec<&LogicalPlan>

Return the logical plan’s inputs.

fn schema(&self) -> &DFSchemaRef

Return the output schema of this logical plan node.

fn expressions(&self) -> Vec<Expr>

Returns all expressions in the current logical plan node. This should not include expressions of any inputs (aka non-recursively). These expressions are used for optimizer passes and rewrites.

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

Write a single line, human readable string to f for use in explain plan.

fn with_exprs_and_inputs( &self, _exprs: Vec<Expr>, inputs: Vec<LogicalPlan>, ) -> DfResult<Self>

Create a new UserDefinedLogicalNode with the specified children and expressions. This function is used during optimization when the plan is being rewritten and a new instance of the UserDefinedLogicalNode must be created.

fn check_invariants( &self, _check: InvariantLevel, ) -> Result<(), DataFusionError>

Perform check of invariants for the extension node.

fn prevent_predicate_push_down_columns(&self) -> HashSet<String>

A list of output columns (e.g. the names of columns in self.schema()) for which predicates can not be pushed below this node without changing the output.

fn necessary_children_exprs( &self, _output_columns: &[usize], ) -> Option<Vec<Vec<usize>>>

Returns the necessary input columns for this node required to compute the columns in the output schema

fn supports_limit_pushdown(&self) -> bool

Returns true if a limit can be safely pushed down through this UserDefinedLogicalNode node.