Struct StreamingDag 

pub struct StreamingDag { /* private fields */ }

The complete DAG topology.

Constructed in Ring 2 via DagBuilder or from SQL CREATE MATERIALIZED VIEW chains. Once built, the topology is immutable and can be executed in Ring 0.

Implementations

impl StreamingDag

pub fn new() -> Self

Creates a new empty DAG.

pub fn add_node( &mut self, name: impl Into<String>, node_type: DagNodeType, output_schema: SchemaRef, ) -> Result<NodeId, DagError>

Adds a node to the DAG.

Errors

Returns DagError::DuplicateNode if a node with the same name exists.

pub fn add_edge( &mut self, source: NodeId, target: NodeId, ) -> Result<EdgeId, DagError>

Adds an edge between two nodes.

Errors

Returns DagError::NodeNotFound if either node does not exist. Returns DagError::CycleDetected if the edge would create a self-loop.

pub fn finalize(&mut self) -> Result<(), DagError>

Finalizes the DAG: validates topology, computes execution order, derives channel types, and identifies shared stages.

Errors

Returns DagError::EmptyDag if the DAG has no nodes. Returns DagError::CycleDetected if the graph contains cycles. Returns DagError::DisconnectedNode if a non-source, non-sink node has no inputs or no outputs. Returns DagError::FanOutLimitExceeded if any node exceeds the maximum fan-out limit.

pub fn validate(&self) -> Result<(), DagError>

Validates the DAG topology without modifying internal state.

Errors

Returns errors for cycles, disconnected nodes, or schema mismatches.

pub fn node_count(&self) -> usize

Returns the number of nodes in the DAG.

pub fn edge_count(&self) -> usize

Returns the number of edges in the DAG.

pub fn node(&self, id: NodeId) -> Option<&DagNode>

Returns a reference to a node by ID.

pub fn edge(&self, id: EdgeId) -> Option<&DagEdge>

Returns a reference to an edge by ID.

pub fn nodes(&self) -> &FxHashMap<NodeId, DagNode>

Returns all nodes.

pub fn edges(&self) -> &FxHashMap<EdgeId, DagEdge>

Returns all edges.

pub fn node_id_by_name(&self, name: &str) -> Option<NodeId>

Returns the NodeId for a given node name.

pub fn node_name(&self, id: NodeId) -> Option<String>

Returns the node name for a given NodeId.

pub fn outgoing_edge_count(&self, node: NodeId) -> usize

Returns the number of outgoing edges from a node.

pub fn incoming_edge_count(&self, node: NodeId) -> usize

Returns the number of incoming edges to a node.

pub fn sources(&self) -> &[NodeId]

Returns all source nodes (nodes with no inputs).

pub fn sinks(&self) -> &[NodeId]

Returns all sink nodes (nodes with no outputs).

pub fn execution_order(&self) -> &[NodeId]

Returns nodes in topological execution order (dependencies first).

pub fn shared_stages(&self) -> &FxHashMap<NodeId, SharedStageMetadata>

Returns metadata for shared stages (nodes with fan-out > 1).

pub fn is_finalized(&self) -> bool

Returns whether the DAG has been finalized.

impl StreamingDag

pub fn from_mv_registry( registry: &MvRegistry, base_table_schemas: &FxHashMap<String, SchemaRef>, ) -> Result<Self, DagError>

Constructs a DAG from an MvRegistry and base table schemas.

Creates a Source node for each base table and a MaterializedView node for each MV, then connects them according to the registry’s dependency graph. The resulting DAG is finalized and ready for execution.

Arguments

• registry - The MV registry with dependency information
• base_table_schemas - Schemas for each base table referenced by MVs

Errors

Returns DagError::EmptyDag if the registry is empty and has no base tables. Returns DagError::BaseTableSchemaNotFound if a base table schema is missing.

Trait Implementations

impl Debug for StreamingDag

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

Formats the value using the given formatter.

impl Default for StreamingDag

fn default() -> Self

Returns the “default value” for a type.