Trait GraphReader 

pub trait GraphReader: Send + Sync {
    // Required methods
    fn get_node(&self, id: NodeId) -> Result<Option<Node>>;
    fn get_edge(&self, id: EdgeId) -> Result<Option<Edge>>;
    fn all_node_ids(&self) -> Result<Vec<NodeId>>;
    fn nodes_by_label(&self, label: &str) -> Result<Vec<NodeId>>;
    fn nodes_by_property(
        &self,
        label: &str,
        property: &str,
        value: &Property,
    ) -> Result<Vec<NodeId>>;
    fn outgoing(&self, id: NodeId) -> Result<Vec<(EdgeId, NodeId)>>;
    fn incoming(&self, id: NodeId) -> Result<Vec<(EdgeId, NodeId)>>;

    // Provided methods
    fn list_property_indexes(&self) -> Result<Vec<(String, String)>> { ... }
    fn list_property_constraints(&self) -> Result<Vec<PropertyConstraintSpec>> { ... }
}

Read-side counterpart to crate::GraphWriter. Gives the executor a uniform view of the graph regardless of whether the data behind it lives entirely in a local storage engine (single-node or full-replica Raft mode) or is sharded across cluster peers (routing mode, where a partitioned reader fans out point reads to owners and scatter-gathers bulk scans).

Methods are sync because the executor’s iterator model is sync. Async- backed implementations (e.g. a remote reader that talks gRPC) bridge via Handle::block_on; callers must run the executor inside spawn_blocking so they don’t stall the tokio runtime.

Required Methods

fn get_node(&self, id: NodeId) -> Result<Option<Node>>

fn get_edge(&self, id: EdgeId) -> Result<Option<Edge>>

fn all_node_ids(&self) -> Result<Vec<NodeId>>

fn nodes_by_label(&self, label: &str) -> Result<Vec<NodeId>>

fn nodes_by_property( &self, label: &str, property: &str, value: &Property, ) -> Result<Vec<NodeId>>

Equality lookup via a property index. Callers (planner) must have verified the (label, property) index exists before emitting this call — fallback implementations are free to do a label-scan-and-filter for impls that don’t maintain their own property index, but the storage-backed reader treats a call on a non-existent index as an empty result since no entries are maintained.

fn outgoing(&self, id: NodeId) -> Result<Vec<(EdgeId, NodeId)>>

fn incoming(&self, id: NodeId) -> Result<Vec<(EdgeId, NodeId)>>

Provided Methods

fn list_property_indexes(&self) -> Result<Vec<(String, String)>>

Snapshot the (label, property) pairs of every property index visible through this reader. Used by SHOW INDEXES. Default impl returns empty — the storage-backed reader overrides via the blanket impl, and partitioned/overlay readers delegate to their bases.

fn list_property_constraints(&self) -> Result<Vec<PropertyConstraintSpec>>

Snapshot every registered constraint visible through this reader, for SHOW CONSTRAINTS and db.constraints(). Default impl returns empty; storage-backed readers override.

Implementors

impl GraphReader for StorageReaderAdapter<'_>

impl<T: StorageEngine> GraphReader for T

Blanket impl: any sized type that implements StorageEngine is automatically a GraphReader. Covers the concrete meshdb_storage::RocksDbStorageEngine — a &RocksDbStorageEngine coerces to &dyn GraphReader via this blanket.

Not covered: dyn StorageEngine itself. Rust does not transitively coerce &dyn StorageEngine to &dyn GraphReader because trait objects of unrelated traits carry different vtables and there’s no supertrait relationship connecting them. Call sites that hold a &dyn StorageEngine should use StorageReaderAdapter to wrap it as a GraphReader.